Electrical Systems Vocabulary Practice
The minimum electrical service current for a modern single-family house is
100 amps. Anything smaller is considered a reportable deficiency, even if the service is original.
The maximum flexible cord length is:
36 inches for a food-waste disposer. 48 inches for a range hood and a trash compactor. 78 inches for a built-in dishwashing machine.
Light fixtures controlled from three or more locations require a 3-way switch at each end of the circuit and
4-way switches in the middle.
Surface-mounted fluorescent fixtures and recessed incandescent, LED, and fluorescent fixtures should not be located within
6 inches from the closet storage areas.
Enclosure (electrical)
A case or cabinet intended to prevent accidental contact with energized parts; a panelboard is housed inside an enclosure.
Grounded (Neutral) Conductor
A conductor that is intentionally connected to the earth; this describes what is often called the neutral conductor.
Grounding electrode conductor (GEC)
A conductor that runs between the grounding electrode and an accessible point downstream from where the grounded service entrance conductor connects to the service drop or lateral; the GEC connection is usually at the service equipment.
Peak power and continuous power are different.
Generators, especially the portable models, are not intended to operate near peak power for long periods of time.
A common color for PVC is
Gray, but other colors are made.
Like solar PV systems, wind turbine systems are either
Grid-connected or stand alone.
Flexible cords often supply electricity to
Kitchen appliances.
It is important to note that different dimmers are required for different devices.
LED and florescent lamps, for example, often require a special dimmer designed for each of those lamps. Ceiling fans often require specially designed dimmers as well.
The other problem with cloth-covered NM, shared by most old wiring methods, is
Lack of an EGC. Some home inspectors report the presence of cloth-covered NM, especially if the visible sheathing appears deteriorated.
Receptacles installed before NEMA standards may have different slot orientations compared to modern receptacles.
Most of these receptacles have been replaced, but home inspectors may still encounter them.
Some comply with current limitations on allowing air to flow through them between conditioned and unconditioned space.
Most older recessed lights do not comply with current requirements.
Fires often start in one of two ways.
Some fires start by producing a lot of flame but little smoke. Some fires start by producing a lot of smoke but little flame. There are two types of smoke alarms.
A load controller is a device that allows
The electric utility to temporarily disconnect the electricity to a device during peak demand.
In most cases, light fixtures are mounted on and supported by
The electrical box.
High Voltage (120/240 volt) system
The electrical system of a house, from a home inspection perspective is
The problems with the COPALUM connector include
The fact that it is expensive, partly because the materials and tools are proprietary, and because electricians must be trained to use them.
SE is a factory-made assembly of insulated conductors and a typically uninsulated EGC.
The flexible nonmetallic covering is made from PVC.
The hanging rod storage area extends vertically from
The floor to the highest rod or 6 feet, whichever is higher, and horizontally 2 feet from the walls.
Flat NM should be stapled with the flat side toward
The framing member.
Toxic or flammable transfer liquids and gasses may not be used as the heat transfer medium.
This includes ethylene glycol (automobile antifreeze).
Flexible cords may not be installed within or through walls, ceilings, and floors.
This includes suspended and drop ceilings.
Receptacles serving walls in habitable rooms should be spaced so that no point along the wall is more than 6 feet from a receptacle.
This means receptacles are often spaced about every 12 feet.
What about replacing all the switches and receptacles with CO/ALR devices?
This might help the situation with aluminum wire made after 1972, but this solution doesn't address the creep problem of old technology aluminum wire. This solution also does not address other aluminum wire terminations such as light outlets.
Home inspectors may wish to consider reporting very heavy light fixtures and recommending evaluation if support cannot be confirmed.
This situation is uncommon.
There should be a switch near the top and bottom landings if there are six or more risers.
This switch should be a 3-way or 4-way switch so that the light can be controlled at the top and bottom of the stairway.
Tin-coated copper wire was most popular in the 1940s and 1950s.
You could find it in older houses too, and in houses built as late as the 1960s.
Photoelectric alarms are slightly less responsive than
Than ionization alarms at detecting flaming fires.
The neutral slot is slightly larger
Than the energized slot.
Smoke alarm and carbon monoxide alarm installation requirements include:
(1) connection of all smoke alarms to each other such that if one alarm is activated all alarms sound (interconnection may be hard wired or wireless) (2) primary power provided by the utility power to the building (3) back-up power provided by a battery in case the fire disrupts the utility power to the building. Carbon monoxide alarm interconnection is a new requirement, so most houses will not comply.
Flexible cords are cables that are usually:
(1) made from stranded conductors, (2) terminate with an attachment plug, (3) intended to connect an appliance to an outlet that is usually a receptacle. Flexible cords include extension cords.
Correctly installed knob and tube wiring should have these characteristics. Knob and tube wiring that does not comply with these is a reportable deficiency.
1. At least 1 inch distance between the wires and objects like walls, floors, and framing. 2. At least 3 inches distance between the wires. 3. Not more than 6 inches between knobs and a wire splice, including splices in boxes. 4. Not more than 4 ½ feet between knobs in wire runs. 5. Wires run on the sides of joists, rafters, and studs, not on top. 6. Tubes installed where the wires penetrate framing. 7. Taps between knob and tube wires and other knob and tube wires may occur outside of covered junction boxes. The taps should be soldered and taped using friction tape. 8. Taps between knob and tube wires and other wiring methods should occur inside a covered junction box or conduit body. 9. Wiring methods should enter boxes with appropriate protection and should be secured near the box as required. Each knob and tube wire should enter the box through a separate opening protected by a bushing. NM cable should enter the box through a clamped opening and should be secured within 12 inches from the box.
Typical Defects, Light Fixture and Ceiling Fans
1. Loose fixture or fan 2. Damaged, scorched, aged, fixture or fan 3. Absent parts 4. Exposed conductors in a fixture or fan box 5. Gap between light fixture and wall or ceiling 6. Damp or wet area fixture not installed where required 7. Interior fixture or fan installed outdoors 8. Inadequately supported fixture or fan 9. Fixture or fan does not function using nearby switches 10. Hanging fixture or ceiling fan too close to tub or shower 11. Fixture too close to clothes closet storage area 12. Exposed incandescent bulb in clothes closet 13. Recessed light operates intermittently 14. Ceiling fan unbalanced, wobbles.
Typical Defects, Receptacles
1. Loose receptacles (e.g., receptacle moves when plug inserted) 2. Damaged, scorched, aged/worn, or painted receptacles (e.g., plug falls out of receptacle) 3. Absent, damaged, or loose cover plates 4. Gap between receptacle and cover plate or between cover plate and wall 5. Damp or wet area cover not installed where required, or cover damaged 6. Receptacle connected to an improper branch circuit, (e.g., receptacle not in a bathroom is on the bathroom branch circuit) 7. Inadequately supported boxes 8. Improperly wired receptacles, (e.g., reverse polarity, not grounded, open neutral) 9. No power at receptacles 10. Receptacle ampacity rating not compatible with branch circuit 11. Receptacle not installed where required, (e.g., kitchen countertop receptacles too far apart) 12. Receptacle installed where not allowed, (e.g., above bathtub 13. Receptacles not AFCI or GFCI protected where required.
Typical Defects, Switches
1. Loose switches (e.g., switch moves when operated) 2. Damaged, scorched, aged/worn, or painted switches (e.g., switch makes noise (arcs) when operated 3. Absent, damaged, or loose cover plate 4. Gap between switch and cover plate or between cover plate and wall 5. Damp or wet area cover not installed where required, or cover is damaged 6. Inadequately supported switch box 7. No power at switch 8. 3-way and 4-way switches do not function properly in all switch positions 9. Dimmer switches do not function properly 10. Switch installed where not allowed (e.g., above bathtub) 11. Switch operates intermittently 12. Switch unusually warm 13. Switch appears to control a load greater than its ampacity rating 14. Switch installed upside down 15. Switch located behind a door or in another inconvenient location.
Electrical Bonding occurs when:
1. Metal that could carry electricity (but is not supposed to) 2. Is intentionally connected together to provide a permanent low resistance return path 3. That is capable of conducting all electricity accidentally carried by the metal back to its source.
Typical Defects for PV Systems:
1. PV system disconnected or not functioning (display on inverter usually shows system status) 2. Backfed PV circuit breaker not secured in panelboard 3. Components not labeled 4. Absent disconnect switches 5. Exposed conductors (except where intended) 6. Array tracking module not functioning (difficult to determine during a home inspection) 7. Metal components not bonded, or gaps in component physical or electrical connection 8. Panels cover vents and exhaust terminations (okay if space between panel and vent or termination at least as large as the opening) 9. Damaged panels including scratches on glass 10. Significant shading of arrays (may be accounted for in the system design).
Typical defects that home inspectors should report include:
1. Splices and taps not contained within an approved and covered box, 2. Box does not have an approved cover, 3. Box knockout does not have an approved cover, 4. Cable enters box without intact sheathing, at least ¼ inch of sheathing should enter the box, 5. Junction box concealed (usually not visible), 6.Wiring method not properly secured near box or enclosure or not secured along run, 7. Wiring method not protected against physical damage, 8. Wiring method installed outside and not approved for outside installation, 9. NM and AC cable installed outside or in buried conduit, 10. Cable or conductors enter metal box without cable clamp or busing, 11. Metal box not grounded (bonded), 12. Wiring method deteriorated or damaged, 13. Cable or conductors repaired with electrical tape or with other unapproved material, 14. Conduit loose at or around enclosures, 15. Extension cord used as permanent wiring, 16. Attachment plug provides electricity to permanent wiring method, 17. Flexible cord passes through or installed in a ceiling, wall, or floor.
Solar water Heating Typical Defects
1. System disconnected or not functioning (improper functioning may be difficult to visually determine), 2. Absent backflow preventer, 3. Absent or improperly installed pressure relief valve, temperature/pressure relief valve, or extension pipe, 4. Absent, improperly installed, or deteriorated pipe insulation, 5. Leaks from or inside collector, and leaks from pipes, 6. Damaged or corroded components, 7. Absent expansion tank where required, 8. Shading of collector, 9. Dirt on collector, 10. Leaks at roof mounts (for roof-mounted collectors), 11. Deformed roof framing (roof-mounted collectors filled with water are heavy), 12. Absent labels where required, such as at on collectors, on storage tanks, and at drain and fill valves.
Typical Defects Wind Turbines
1. Wind system disconnected or not functioning (display on inverter usually shows system status), 2. Backfed wind circuit breaker not secured in panelboard, 3. Components not labeled, 4. Absent disconnect switches, 5. Exposed conductors (except where intended), 6. Metal components not bonded, or gaps in component physical or electrical connection, 7. Tower not grounded, 8. Damaged or deteriorated components, 9. Surge protector not installed.
For example, a fixed in place appliance should not be rated at more than 7.5 amps and a plug and cord connected appliance should not be rated at more than
12 amps on a 15 amp, 120 volt general lighting branch circuit.
Industry convention places wall receptacles at about
12 inches above the floor and countertop receptacles at about 45 inches above the floor, but these heights are not required.
Surface-mounted incandescent and LED fixtures should not be located within
12 inches from the closet storage areas.
GFCI protected residential branch circuits at 20 amps or less may be buried at least
12 inches regardless of the wiring method.
A dishwasher and food-waste disposer may each need a dedicated
120 volt circuit.
In residential electrical systems, the voltage between the hot (ungrounded) wires and the neutral (grounded) wire is
120 volts.
Most lights in houses operate on
120 volts.
Receptacles on 15 amp general lighting and receptacle branch circuits should be
15 amp rated receptacles.
Switches for use by people with disabilities are usually located between
15 and 48 inches above the floor, depending on whether an obstruction is in front of the switch.
Receptacles on 20 amp general lighting and receptacle branch circuits should be
15 or 20 amp rated receptacles.
Lighting branch circuits in houses are restricted to
15 or 20 amps, 120 volts.
Receptacles serving general lighting and receptacle branch circuits are limited to those rated at
15 or 20 amps.
Floor receptacles may be used to comply if the receptacle is within
18 inches from the wall.
Receptacle types began to be standardized in the
1930s through the efforts of the National Electrical Manufacturers Association (NEMA).
GFCI protected receptacles serving walls above kitchen countertops should be spaced so that no point along the wall above the countertop is more than
2 feet from a receptacle. This means receptacles are often spaced about every 4 feet.
At least one GFCI protected receptacle should be located at a peninsula if it measures more than
2 feet long (measured from the perpendicular wall closest to the peninsula) and 1 foot wide.
The required countertop receptacles should not be located more than
20 inches above the countertop or in an enclosed space such as an appliance garage. Receptacles may be located in these areas, but they do not count as one of the required receptacles
PVC should be supported every
3 feet for 1 inch and smaller sizes, 5 feet for 1¼ inch and larger sizes, and within 3 feet from boxes and terminations.
Hanging light fixtures, track lights, and ceiling fans should have no parts located within a zone from
3 feet horizontally and 8 feet vertically from the tub rim or shower threshold. No parts includes nonconductive parts such as glass and fan blades.
Recessed lights that are not IC rated should have at least
3 inches of space between the light and insulation.
In modern houses, the 120 volt receptacles will be the
3-slot grounded polarized receptacle.
Modern receptacles should be
3-slot grounded receptacles, and should be tamper-resistant receptacles. Existing receptacles may remain, but if replaced, the new receptacles should comply with modern standards.
SE should be supported every
30 inches and within 12 inches from boxes and terminations.
Industry convention locates wall switches at about
48 inches above the floor, but this height is not required.
One fixed in place appliance should not exceed
50% of a general lighting branch circuit amperage rating.
The maximum height of a switch is
79 inches above the floor when the switch is in the up position.
One cord-and-plug connected appliance should not exceed
80% of a general lighting branch circuit amperage rating.
Branch circuit, multiwire
A branch circuit in which two energized conductors share one neutral conductor; examples can include clothes dryers, ranges and other cooking appliances, and split-wire receptacle circuits; 240 volt water heaters and condensers for air conditioners and heat pumps are not usually multiwire branch circuits.
Light fixtures controlled from two locations require
A 3-way switch in both locations.
EGC (Equipment Grounding Conductor)
A bare or green insulated conductor that provides a ground fault current path (a bonding connection) for equipment with metal cases and parts; these have been installed in most house branch circuit wiring since around 1960.
Standards of practice usually require only that the home inspector report the presence or absence of smoke alarms and carbon monoxide alarms.
A few standards require testing these alarms, but this is the exception.
Joules Law
A formula for calculating heat in an electrical circuit expressed as Heat = Current^2 X Resistance X Time.
Overcurrent protection device (OPD)
A fuse or a circuit breaker; overcurrent protection devices interrupt the flow of electricity when a set current flow is exceeded (an overload), or when a short circuit fault is detected; these devices prevent conductors and devices from overheating and causing fires.
Conductor
A material, such as copper or aluminum, that permits electricity to flow with low resistance; wires are conductors.
Dead front cover
A panel that is removed to gain access to the energized components inside an enclosure; the dead front cover is usually behind a door that must be swung or lifted to gain access to the dead front cover.
Modern receptacles are polarized; some older receptacles are not.
A polarized receptacle is one in which a slot is a different size or orientation.
Smoke alarm location requirements for split-level houses can be confusing.
A smoke alarm is required only on the upper level if there is no door between levels, and if the upper level is less than one full story above the lower level. Some jurisdictions require a smoke alarm on each level of a split-level house, and manufacturers usually recommend this as well.
Other Solar water Heating system components may include
A temperature/pressure gauge, one or more pressure relief valves or temperature/pressure relief valves, and an expansion tank (if the system uses pressurized transfer fluids). Depending on the system type, a heat exchanger, pump, and a pump controller may be part of the system.
Receptacles in Wet and Damp Areas
A wet area is one exposed to large amounts of liquid water such as an exterior wall that is not protected by a roof. A damp area is one exposed to small amounts of liquid water such as an exterior wall under a roof.
Many smoke alarm manufacturers recommend replacing smoke alarms after
About ten years.
In new homes, at least 75% of the light bulbs should be high-efficacy bulbs.
Examples of these bulbs are: CFLs, LEDs, and fluorescent.
Ionization alarms are more prone to false alarms than are photoelectric alarms.
Alarms that combine ionization and photoelectric sensors in one unit can have higher false alarm rates than single sensor alarms. False alarm rates, by themselves, are a good reason to avoid ionization alarms.
Home inspectors should test 3-way and 4-way switches from
All locations. Sometimes the light will function when a switch is in one position but not when a switch is in a different position.
Flexible cords may not be
Altered, spliced, or extended.
Anti-oxidant paste is also highly recommended where
Aluminum and copper wires are connected together.
A wet area is one exposed to large amounts of liquid water such as
An exterior wall that is not protected by a roof.
A damp area is one exposed to small amounts of liquid water such as
An exterior wall under a roof.
Receptacle
An outlet designed to accept a plug that supplies electricity to an appliance.
Because of the tendency of aluminum to oxidize, using
Anti-oxidant paste at terminals is highly recommended.
Light fixtures with exposed incandescent bulbs should not be located
Anywhere in a clothes closet.
Unfinished Basement Receptacles
At least one GFCI protected receptacle should be installed in an unfinished basement. This is in addition to receptacles required for appliances such as HVAC.
Garage and Accessory Building Receptacles
At least one GFCI protected receptacle should be installed in each vehicle bay of an attached garage, and in any detached garage if it is provided with electricity.
Laundry Receptacles
At least one GFCI protected receptacle should be installed in the laundry.
Hallway Receptacles
At least one receptacle should be installed in a hallway that is 10 feet or more long when measured along the center of the hallway.
HVAC Service Receptacles
At least one receptacle should be installed within 25 feet from and on the same level as HVAC equipment such as furnaces and condensers.
Smoke alarms should not be installed near combustion sources such as in garages and near combustion equipment such furnaces, boilers, water heaters, and fireplaces of all types.
At least twenty feet of separation is recommended by some manufacturers. Nuisance activation is also common when smoke alarms are installed kitchens, so they should not be installed there.
Every outlet (meaning switch, receptacle, light, and appliance) with solid-conductor aluminum wiring must be repaired.
At up to $60 or more per outlet, this gets expensive. Finding an electrician who can do this may be difficult, at any price.
Solar water Heater Collector types include batch (integral) storage, flat plate, and insulated (evacuated) tube.
Batch collectors consist of a black tank in an insulated box. The water is heated in the tank and stored there until used. Flat plate collectors consist of pipes with black metal fins in an insulated box. Water absorbs heat as it moves through the pipes. Insulated tube collectors consist of glass tubes with metal fins enclosed in an air-sealed outer tubes. Water absorbs heat as it moves through the tubes.
Other places that smoke alarms should not be installed include
Bathrooms and laundry rooms (due to high humidity), near fans and operable windows (air currents could prevent smoke from reaching the sensor), and near florescent lights (electrical interference with the sensor).
Receptacles may not be installed in and above
Bathtubs and Showers.
Switches should not be installed in wet locations inside
Bathtubs and Showers.
If the house electricity system is not connected to the electricity grid, the system may serve most or all of the loads.
Batteries and generators may provide electricity at night and at other times when the system cannot provide enough electricity for the occupant's needs. A wind turbine may be used to supplement a stand-alone PV system.
A home inspector may want to go beyond the minimum standard and test the alarm.
Be careful; testing alarms and reporting the results can be a case where no good deed goes unpunished.
Three-slot grounded receptacles may not
Be ungrounded.
Electricity (Start to Finish)
Begins at a source (e.g., a power plant, a generator, solar photovoltaic panels), flows through an energized conductor (hot wire), performs work at a load (e.g., a light bulb, a range), and returns to the source through a grounded conductor (neutral wire)
Any non-conductive contaminants such as paint and rust must be removed at the
Bonding connection point.
Satellite and cable TV coax cable must also be bonded.
Bonding connections at electrical fittings and boxes must be physically secure and provide a low resistance electrical connection.
Receptacle and switch boxes should be securely supported.
Boxes supported by conduit should be supported by at least two pieces of conduit. The conduit should be secured within 18 inches of the box.
Switch and receptacle boxes should be securely supported.
Boxes supported by conduit should be supported by at least two pieces of conduit. The conduit should be secured within 18 inches of the box.
The problem with solid-conductor aluminum wiring was that buildings use materials different from that which is found in the electrical transmission and distribution grid.
Buildings have lots of devices like switches, receptacles, and circuit breakers. There are copper wires, such as in light fixtures and appliances, that need to connect to the aluminum wires. The building world was designed for copper wires. Apparently, nobody considered the problems that could occur when you throw aluminum into this copper world.
The next attempt to fix the problem of terminals on devices that were designed for copper did not work well with aluminum wire was devices labeled
CO/ALR. These devices work and have been required by the NEC since 1981.
Cable installed in crawl spaces is usually not considered subject to physical damage, nor is cable installed away from attic access openings to the attic.
Cable installed within 7 feet vertically and 6 feet horizontally from an attic access opening is considered subject to physical damage.
The following situations may be considered subject to physical damage:
Cable, such as NM, AC, and UF installed under kitchen sinks, and cable within reach on finished walls and in exposed walls including in unfinished walls in basements and garages.
Wiring methods
Cables and raceways approved for distributing electricity from the service point to panelboards and outlets; examples include armored cable, nonmetallic sheathed cable, and various types of conduit and tubing.
Examples of multiwire branch circuits include
Clothes dryer and range circuits are also examples.
The service life of residential depends on the Solar water Heating system type.
Collectors may serve for 20 years or more if properly maintained; direct systems are prone to mineral buildup in the collectors. Mechanical and electronic parts may serve between 5 and 15 years if properly maintained.
NM may not be embedded in
Concrete or run in conduit and tubing embedded in concrete.
Feeder conductors
Conductors from the service equipment or from a panelboard that supply electricity to another panelboard such as a subpanel.
Branch circuit
Conductors that begin at a circuit breaker or fuse and serve one or more outlets.
Around 1964, somebody had what must have seemed like a good idea at the time.
Copper had become expensive, so why not make solid-conductor building wiring out of aluminum? Aluminum wire had been used for years to transmit and distribute electricity, and had even been used in some building wiring. And so in 1964 they started making solid-conductor aluminum wiring in #8 - 12 AWG nonmetallic sheathed cable intended for residential use.
If electricity flows where not intended, like between copper and aluminum wires or between aluminum wires and steel terminals intended for copper wires,
Corrosion can occur.
Light fixtures within the tub or shower perimeter should be listed for
Damp areas, and if shower spray is possible should be listed for wet areas.
Rocker switches are sometimes referred to by the brand name
Decora, which is owned by Lutron. Use of brand names in reports should be avoided.
Photoelectric alarms are good at
Detecting smoky (smoldering) fires, which is the way many home fires start.
Copper-clad aluminum wire is rated as aluminum wire when
Determining wire ampacity.
A galvanic reaction (electrolysis) occurs when
Different metals are in contact in the presence of moisture. This may cause electricity to flow. This is a good thing, because without it, there would be no batteries.
Solar water heating systems can be classified based on the method of heating the water, and on the method of moving the water through the pipes.
Direct systems run the water through a collector and heat the water itself. Direct systems must be shut down and drained when the outside temperature falls below freezing. Indirect systems heat a transfer fluid (one that does not freeze at normal outside temperatures) which in turn heats the water in a heat exchanger. Passive systems rely on convection to move water (hot water rises as it is heated). Active systems use a pump to move water or the transfer fluid.
Receptacles and switches should be connected to the
EGC, as should the metal box in which they might be installed.
Switches and receptacles should be connected to the
EGC, as should the metal box in which they might be installed.
At least one GFCI protected receptacle should be located within 3 feet from the outside edge of
Each bathroom sink. The required receptacles may be mounted on the cabinet if the receptacle is not more than 12 inches below the countertop.
Knob and tube was most popular from the
Early 1900s to the 1930s. Knob and tube is considered obsolete; however, it may be installed today as an extension of existing knob and tube wiring or by permission from the local building department.
Three phase electrical service
Electrical service consisting of three energized conductors and one grounded conductor; this service type is mostly for commercial and industrial buildings.
Single phase electrical service
Electrical service consisting of two energized 120 volt conductors and one grounded conductor; this is by far the most common residential electrical service.
Raceway
Enclosed metallic or nonmetallic components designed and listed for holding conductors or cables between points in the electricity distribution system of the house; examples include various types of conduit and tubing.
Appliances listed for cord-and-plug connection may use the plug as the disconnecting means.
Examples include food-waste disposers, trash compactors, dishwashers, and microwave ovens.
Fixed in place appliances should have a means to disconnect electricity to the appliance for the safety of service personnel.
Examples of appliances that usually have a separate disconnecting means include furnaces, boilers, air handlers, air conditioning condensers, electric baseboard heaters, sump pumps, sewage ejector pumps, and swimming pool pumps.
The bend radius of cables such as AC and NM should not be less than
Five times the cable diameter.
Carbon monoxide alarms have a shorter service life of around
Five to seven years.
The two primary general concerns regarding light fixture installation are
Fixture support and grounding of exposed metal.
Interior receptacles may be installed in
Floors (with listed floor boxes), in ceilings, or anywhere in between.
Alternating current
Flows back and forth at a frequency of 60 cycles per second (in North American electric power systems). Do not try to envision how alternating current flows, just trust that it does. Alternating current is used in modern utility electrical distribution systems.
Direct current
Flows in one direction from a positive pole to a negative pole. Direct current comes from batteries and from some power supplies used for electronic devices.
Receptacles should be installed so that they are
Flush with or protrude from the cover plate, and so that they do not move when a plug is inserted or removed.
Polarized receptacles help keep metal on devices such as lamps
From becoming energized.
Wind turbine towers are either self-supporting or supported using guy cables.
Guyed towers are less expensive, but require more land to install the guy cables. Some towers can be raised and lowered to allow easier maintenance of the rotor and generator module.
A clothes closet is divided into two storage areas.
Hanging rod storage area and shelf storage area.
Joule's law states that
Heat in an electrical circuit is based on the amount of current flowing, the resistance in the circuit, and time. Increase resistance and heat increases. Heat can cause electrical fires.
Few, if any, alternative energy systems may be legally installed without a permit.
Home inspectors should consider recommending that clients request evidence of a permit and approved inspections when an alternative energy is present.
Many home inspectors test the remote control if it is available.
Home inspectors should report that a fan was not operated if operation is only by remote control and if the remote control was not located.
Generators and all associated components are out of scope of a home inspection.
Home inspectors should report the presence of a generator, and of any related components such as a transfer switch, disclaim inspection, and recommend specialist evaluation to determine the condition and functioning of a generator system.
Alternative energy systems and all associated components are out of scope of a home inspection.
Home inspectors should report the presence of a these systems, and of any related components, disclaim inspection, and recommend specialist evaluation to determine the condition and functioning of the system. Home inspectors who elect to report about these systems should disclose the limitations of their inspection and reporting.
In new construction, at least one carbon monoxide alarm is required in
Houses with a fuel-burning appliance and in houses with an attached garage.
Other alternative (renewable) energy systems include:
Hydroelectricity (electricity generated by water movement), nuclear energy, marine hydrokinetic systems (electricity produced by tides or ocean currents), geothermal (systems using heat from deep within the planet), burning various types of biomass (such as pellets made from wood waste products), hydrogen fuel cells, and algae fuel.
Ohm's Law we know that:
I(current in amps) = E(voltage in volts) / R(resistance in ohms). If E=120 volts and R=10 ohms, then 120/10=12 amps. This poorly bonded circuit will carry 12 amps. Twelve amps will not trip a 15 amp circuit breaker, but it is more than enough to kill the rat or anyone else.
IC rated recessed lights should be labeled as such, but the label is usually on the inside of the can.
Identifying an IC rated recessed light from the outside is difficult. Home inspectors may wish to consider whether and how to report recessed lights that are in contact with insulation.
A receptacle should be located at an island if it measures more than 2 feet long and 1 foot wide.
If the island contains a sink or cooking appliance, the kitchen countertop wall receptacle requirements apply. The required receptacles may be mounted on the cabinet if the receptacle is not more than 12 inches below the countertop and if the countertop does not extend more than 6 inches past the cabinet above the receptacle.
Some of these recessed lights can allow significant air leakage to occur.
In addition to the energy costs, the heat and air leakage from these lights can contribute to ice dams and can introduce excess moisture into attics. Excess moisture can lead to staining and damage of wood, and to fungal growth.
At least one smoke alarm is required on each story including basements and habitable attics, but not including crawl spaces and uninhabitable attics.
In fact, smoke alarms and carbon monoxide alarms should not be installed in crawl spaces and attics because the alarms do not function properly in these dirty and unconditioned environments.
The 240 volt receptacles will be the 4-slot grounded receptacle.
In older houses, some 2-slot receptacles may remain as will 3-slot ungrounded 240 volt receptacles.
Copper-clad aluminum wire was produced
In the 1970s. It looks like copper wire except you can see the aluminum wire where the wire is cut.
The materials in an alloy can significantly alter how the metal behaves.
In the case of solid-conductor aluminum wire, the original alloy made the wire brittle and caused a problem called creep.
The switch for exterior lights should be located
Inside the house.
IC rated recessed lights may be covered with
Insulation, although this can cause overheating problems that can cause the thermal cutoff switch to activate and shut off the light.
NM is limited to
Interior dry locations, such as in walls, and in masonry cells that are not exposed to dampness and are not below grade.
Exceptions exist that relieve smoke alarm and carbon monoxide hard wiring and interconnection requirements if the work would require disturbing finish surfaces. Interconnection can be accomplished with listed wireless technology.
Interpretation and enforcement of these updating requirements and exceptions varies widely among jurisdictions.
One of the reasons for the grounding system
Is to help safely deal with voltage surges.
One property of the aluminum alloy used in the original, old technology, solid-conductor aluminum wire is that
It expanded more than copper when the wire got hot. It also expanded at a different rate than the steel device terminals designed for copper.
SE is used as the service entrance conductors between the service point and the service equipment.
It is also used for branch circuits serving large appliances and as feeder cable between panelboards. The neutral conductor must be insulated when used as branch circuit and feeder cable.
The safest and possibly the best solution to solid-conductor aluminum wiring is to rewire the house with copper wire, but clients don't want to hear that.
It is expensive and disruptive, but worth considering.
A newer connector, called AlumiConn, has been available since the early 2000's.
It is much less expensive than the COPALUM connectors and AlumiConn connectors are sold to the public. Selling to the public isn't necessarily a good thing.
Ungrounded 3-slot receptacles are a common defect.
It is not acceptable to install a wire between a receptacle's EGC and neutral terminals. The receptacle tests as grounded when using a 3-light receptacle tester, but it is not grounded. This is sometimes called a bootleg ground, and it is a potential shock hazard because it places electric current into the grounding system.
Anti-oxidant paste is not, however, specifically required by the National Electrical Code (NEC).
It is recommended by some wire manufacturers and is required by some jurisdictions.
PVC may be installed in all locations.
It may be buried and embedded in concrete.
SE may be installed in most locations, except
It may not be buried (USE may be buried) and it may not be embedded in concrete. SE may not be run where subject to physical damage.
NM should be supported every 4½ feet and within 1 foot from boxes and terminations.
It should be supported within 8 inches of most plastic boxes.
Areas where a wind turbine may be practical include
Land within a few miles of large bodies of water (oceans, the Great Lakes), elevated land (near tops of mountains and hills higher than surrounding terrain), and in the Midwest, Northeast, and Northwest.
Stranded aluminum wire is available in AWG sizes #8 and larger and is used for
Large appliance branch circuits and for service entrance and feeder wires. This wire has no problems when installed with devices labeled CO/ALR and circuit breakers labeled CU/AL.
Ceiling fans are not light fixtures; they are appliances.
Light fixture rules do not apply to ceiling fans. Ceiling fans place more load on supports because of blade movement, and because some fan blades are not properly balanced.
Light fixture connection to the EGC is almost always concealed during a home inspection and when concealed is out of scope.
Light fixture support is usually concealed.
Conductors connected to loose receptacles can become loose, arc or overheat, and cause a fire.
Loose receptacles are a common defect, especially receptacles mounted in bathroom mirrors.
Some lights operate on low voltage, usually 12 or 24 volts.
Low voltage lights are especially common in landscape lighting. Low voltage lighting is out of scope of a home inspection regardless of where the lights are located.
The service life of residential wind turbine rotor/generator modules is reported to be similar to solar PV inverters, between about 5 to 15 years.
Many of these modules are too new to have a meaningful service life record.
Grounding electrode
Metal that is in direct contact with the earth and serves as the electrical system grounding connection; examples include copper-coated steel rods, galvanized steel pipes, water service and well pipes, and reinforcing steel encased in the footings.
Longer wires have
More resistance than shorter wires
Light fixtures that weigh not more than six pounds may be supported by
Most electrical boxes.
When NM is installed in holes in framing members, measurement is to the edge of the hole.
NM #10 and smaller should be installed through holes in basement floor joists; it should not be attached to the bottom of floor joists.
A flexible cord should not be made from NM or any other permanent wiring method.
NM may not terminate in a plug.
NM should be protected by
Nail guards when run closer than 1¼ inches to the edge of a framing member such as a stud or a joist.
The second rule, and last, to updating the electrical system is
New work and existing work that is modified or extended should comply with rules in effect when the work is done. This second rule applies regardless of whether a permit was required or issued.
All distances are measured to the storage area, and
Not to the shelf or to the rod.
NM is available in wire gauges from #14 to #2.
Older NM usually has a white jacket for #14 - 10 and a black jacket for larger sizes.
Traditional solar panels should function for between 20 and 25 years, although output declines with age.
Older panels are still functioning, and panels over 50 years old have been reported to be functioning. Inverters should function for between 5 and 15 years. The remaining components should function for between 30 and 50 years.
The ideal smoke alarm location is
On the ceiling at least 4 inches away from the wall.
Wind turbines are not practical everywhere.
One acre or more of land is the recommended the minimum for a wind turbine system. Local zoning regulations should allow a tower 60 feet tall or taller. A 100 foot tall or taller tower is usually recommended for optimal performance.
Some ceiling fans are operated by remote control.
Operating the fan by remote control is out of scope of a home inspection.
Testing the timer function is
Out of scope for a home inspection.
Burial depth is usually not visible during a home inspection, and is usually
Out of scope.
NM may not be installed
Outdoors, including inside conduit and tubing that is installed outdoors and conduit and tubing that is buried. These are considered wet locations.
Fuse
Overcurrent protection device (OPD)
Circuit breaker
Overcurrent protection device (OPD).
Aluminum, like other metals, has a tendency to
Oxidize. Think of oxidation as rust.
PVC conduit is not the same as PVC plumbing pipe.
PVC plumbing pipe may not be substituted for PVC conduit, and PVC conduit may not be substituted for PVC plumbing pipe.
Walls above kitchen countertops include
Partial height walls that extend above peninsulas and islands.
Flexible cords may not be used as a substitute for
Permanent wiring.
Foyer Receptacles
Receptacles should be installed in a foyer with an area more than 60 square feet. A receptacle should be installed in each wall space that is at least 3 feet wide and is not interrupted by doors, tall windows, and similar openings.
Recessed lights in new houses should have sealed cans that limit airflow through the light.
Recessed lights in older houses are rarely sealed.
Wiring method burial depth should be deep enough to
Reduce the chance of accidental damage and the resulting shock hazard that can occur during excavation.
Contact between knob and tube and metal, such as pipes, ducts, foil vapor retarders, and foil radiant barriers is a major
Reportable deficiency.
Oxidation or corrosion on wires (especially on aluminum wires) increases
Resistance at connections such as receptacles and switches.
Rigid Polyvinyl Chloride Conduit (PVC) is a
Round pipe designed for routing and protection of conductors and cables.
Some switches have a small LED light in the switch for
Safety and convenience at night.
PVC comes in two wall thicknesses
Schedule 40 and Schedule 80. Schedule 80 should be used when protection against physical damage is necessary.
Switches also include a wide variety of dimmers that are used to control light output from lamps and to control ceiling fan speed.
Several dimmer types are available including rheostats (old technology), and various types of solid state dimmers. Several dimmer styles are available including rotary, push button, and slide.
A clothes closet is one that contains
Shelves or rods designed for storage of clothing. Pantries and similar storage closets are not included in this section.
Twenty amp rated receptacles may be identified by a
Short notch perpendicular to the neutral slot.
A photoelectric alarm works by shining a light above a sensor at a 90° angle to the light.
Smoke entering the alarm disrupts the light, reflects some of the light toward the sensor, and triggers the alarm.
An ionization alarm works by using radioactive material to ionize the area between two sensors and allow the flow of electricity between the sensors.
Smoke entering the sensor disrupts the flow of electricity and triggers the alarm.
Ionization alarms are significantly less responsive at detecting
Smoky fires, and, in fact, may not activate until it is too late, if at all. They are significantly less responsive at detecting smoky fires, and, in fact, may not activate until it is too late, if at all.
In modern houses, most switches are either
Snap switches or Rocker switches.
Copper-clad aluminum wire does not share the same problems as
Solid-conductor aluminum wire and has not been a problem. It is also uncommon, which may explain why there have been no reported problems
The other problem with aluminum expanding more than copper when the wire gets hot was that over multiple expansion and contraction cycles, aluminum wire at the connections would become distorted, smaller, and brittle, permanently.
Some call this problem cold flow while others call it creep.
Industry convention installs receptacles with the grounding slot down, but this is not required.
Some electricians install wall receptacles with the grounding slot up to indicate a switched receptacle.
The NEC (Article 394.12) does not allow covering knob and tube with thermal insulation in hollow spaces of walls, ceilings, and attics, so thermal insulation-covered knob and tube is a reportable deficiency in most areas.
Some jurisdictions, however, allow thermal insulation-covered knob and tube.
From a home inspection perspective only two recessed light features are important.
Some recessed lights are insulation contact (IC) rated and some are not.
Some solar water heating systems provide hot water for space heating.
Some systems are designed for heating swimming pool water.
Solar water heating systems use solar energy (primarily infrared) increase the temperature of water.
Some systems increase the water temperature to normal domestic hot water temperature and supply hot water directly to the house water distribution system; these are less common. Most systems preheat the water for use in an electric or fuel-fired water heater.
A transfer switch disconnects the house electrical system from the grid and provides electricity to selected branch circuits when the generator is providing electricity.
Some transfer switches perform this function automatically when the generator begins providing electricity; this applies mostly to high-end permanent systems that begin operation automatically when utility electricity ceases. Most transfer switches are manually operated when the occupant engages the generator.
These low-voltage switch systems are specialized and the home inspector should inform the client about this system, and that it may require periodic maintenance because the relays can fail.
Standard hardware store switches will not work as replacements in these systems.
NM may be installed exposed, but not where
Subject to physical damage.
Solar photovoltaic (PV) systems use light from the sun to produce direct current (DC) electricity.
Sunlight (photons) strike a silicon-based solar cell inducing an electric current. Each cell produces a small amount of current at low voltage. Cells are assembled into modules which are connected into panels and arrays to produce enough voltage and current to perform useful work at typical voltage and current levels used by modern loads like lights and appliances.
Alternative energy systems (also called renewable energy sources) are usually defined as
Systems that provide electricity, heat energy, or energy of motion using means other than combustion of fossil fuels (e.g., oil, gas, coal).
Other wind turbine system requirements include
That a surge protective device (lightning arrestor) should be installed between the wind turbine system and loads served by the house electrical system, and that the tower be connected to a grounding electrode.
In most houses, the source of electricity is the transformer belonging to the utility and the low resistance return path is the grounded conductor belonging to the utility.
That is why you should find metal water pipe and gas pipe bonding conductors, and the equipment grounding conductors (EGCs) in electrical cable connected to the grounded terminal bar at or before the service equipment. This low resistance return path is essential. Without a low resistance path, enough current may not flow, so that the overcurrent protection device (OPD) clears the ground fault.
Cloth-covered NM can be found in houses from late 1920s, but is more likely to be found in houses built during
The 1940s and 1950s.
It gets the derogatory nickname, rag wire, from its cotton or rayon sheathing.
The 1960s saw the cloth sheathing give way to PVC sheathing.
Installation on the wall is acceptable if the top of the case is at least 4 inches and less than 12 inches from the ceiling.
The 4 inch distance helps avoid dead air spots that may prevent smoke from reaching the sensor. Smoke tends to collect near the ceiling so the 12 inch distance helps in-sure that rising smoke reaches the sensor.
Carbon monoxide alarm location restrictions are similar to, but not identical to, smoke alarm restrictions.
The 4 inches from ceiling corner dead air location restriction applies, as do the restrictions involving combustion sources, high humidity, fans and operable windows, and kitchens. The 12 inches to ceiling location restriction does not apply to carbon monoxide alarms. In fact, a lower location on a wall may be advantageous in providing a more rapid response to the presence of carbon monoxide. Just be sure that the alarm is above the reach of children.
Most light fixtures should be connected to
The EGC.
Metal face plates should also be connected to
The EGC. This usually occurs through the screws that attach the face plate to the receptacle or switch.
AWG
The abbreviation for American Wire Gauge, a system for identifying the diameter of electrical wires; larger numbers identify smaller diameter wires; #14 (pronounced number 14 or 14 gauge) is the smallest wire used in house wiring, and 4/0 (pronounced four-oh) is usually the largest.
Tin-coated copper wire looks a lot like solid-conductor aluminum wire, but there are some ways to tell the difference.
The age of the house is one way. Houses built before 1964 might contain solid-conductor aluminum wire, but it is unlikely. Another way is to look carefully at where the wire is cut; you can see the copper there. Still another way is to look at the insulation. If the insulation is plastic, it is not tin-coated copper.
In new construction, at least one carbon monoxide alarm is required in houses with a fuel-burning appliance and in houses with an attached garage. Remember that a fireplace is a fuel-burning appliance.
The alarm should be located near the bedrooms and if the bedrooms are widely separated or are on different stories, then multiple alarms are required.
Current
The amount of electricity in a circuit; (similar to water gallons per minute; water flow in a pipe); unit of measure is the Ampere (Amp); expressed as I in Ohm's Law and Watt's Law equations.
Flexible cords should terminate in a plug that may be inserted into a receptacle, unless
The appliance is listed for use with a flexible cord that may be connected directly to an outlet. Some cooking appliances and furnaces are examples of when direct connection of a flexible cord to an outlet may be acceptable.
A generator will feed electricity into the utility grid system unless the house electrical system is disconnected from the grid.
The backfeeding of electricity into the utility grid is very dangerous to utility workers who are restoring electricity.
Exterior stairways to a basement should have the light at
The bottom landing.
Light fixtures that weigh more than fifty pounds should be supported independently from
The box or by a heavy duty box listed for heavy fixtures.
The difference between smoke alarm and carbon monoxide alarm life expectancies makes combining these devices into one problematic.
The carbon monoxide part could fail before the smoke part, rendering the device only partially functional. Combination devices are relatively new, but the home inspector may want to alert the clients to this service life difference for their future maintenance plans.
Knob and tube wiring gets its name from
The ceramic insulators used to support the conductors and from the ceramic tubes used to protect conductors when they ran through framing members.
The main problem with cloth-covered NM is that
The cloth sheathing and the wire insulation deteriorates and becomes brittle with age.
Flexible cords may not be installed inside panelboard enclosures unless
The cord is listed for this purpose (such as a cord for a swimming pool light).
Receptacles should not be located face up on
The countertop.
System operation begins when direct current electricity flows from the solar arrays through the DC disconnect switch, which is a service and safety device that allows the arrays to be disconnected from the rest of the system when maintenance is necessary.
The direct current electricity flows into the inverter which converts it into alternating current (AC) electricity that can be used in the house or can be fed back into the utility grid for others to use. The AC disconnect switch is another service and safety device that allows the entire solar system to be disconnected from the house electric system when maintenance is necessary. Electricity from the AC disconnect switch flows into a panelboard of the house electric system through a backfed circuit breaker.
The most common modern 120 volt receptacle is
The duplex receptacle, so called because it can accommodate two plugs. The duplex receptacle is counted as two receptacles.
A wall switch-controlled permanent ceiling or wall fixture should be located in every hallway, interior and exterior stairway, attached garage, detached garage where electricity is supplied, and at exterior doors.
The garage vehicle door is not considered an exterior door.
A transfer switch is required to disconnect the house from
The grid while the generator is providing electricity to the house.
Bus (buss, busbar)
The heavy, rigid metal part of a panelboard on which circuit breakers or fuses are mounted; sometimes used to describe metal terminals to which the neutral and equipment grounding conductors (EGCs) are connected.
The shelf storage area extends vertically from
The highest shelf to the ceiling, and horizontally from the widest shelf or 12 inches from the wall, whichever is larger.
When the home inspector tests an alarm by pressing the test button, the home inspector may only be testing the sound producing device.
The home inspector may not be testing the alarm's sensor. There are UL listed aerosol smoke products for testing smoke sensors, but such testing is out of scope for a home inspection.
Each unit of a two-family house or a townhouse may have as little as a 60 amp service; however,
The home inspector may wish to report such a limited service to the client.
Interior stairway lights should be capable of lighting all treads and landings, including the top and bottom landings.
The home inspector should be aware of how the stairway and landings will be illuminated at night, including shadows and unsafe lighting.
Wiring method bends should not damage the component.
The internal diameter of conduit and tubing should not be reduced.
Most small portable generators are gasoline-powered; some are powered by propane.
The large permanent generators are usually powered by natural gas, propane, or diesel.
A wall switch-controlled light should be located in every habitable room and bathroom.
The light fixture should be a permanent ceiling or a wall fixture in kitchens and bathrooms. The light fixture may be controlled by a switched receptacle in other rooms.
Ampacity
The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
There are two types of smoke alarms.
The most common type is the ionization alarm. The less common type is the photoelectric alarm.
There are two ways to deal with this situation if the branch circuit does not have an EGC.
The most common way is to install a GFCI receptacle and label it "NO EQUIPMENT GROUND." The other way is to install an EGC to the nearest available EGC from another branch circuit, or to an EGC in the nearest panelboard.
Modern polarized 120 volt receptacles have:
The neutral slot on the left. The energized slot on the right The equipment grounding slot on the bottom (when installed in the typical grounding slot down position).
The modern 240 volt receptacle has:
The neutral slot on top The two energized slots on the sides The equipment grounding slot on the bottom (when installed in the typical grounding slot down position).
All tin-coated copper wire is near the end of its expected service life.
The old rubber insulation can crack and fail, especially when disturbed.
Note that new requirements in NEC 2014 include that receptacles in an attached garage should be on a dedicated circuit.
The one receptacle for each vehicle bay is also a new requirement. Older houses will usually not comply with this new requirement, and non-compliance is not a defect.
There are no specific limits on the number of receptacles on a general lighting and receptacle branch circuit in houses.
The only requirement is to evenly distribute the load among these branch circuits.
The fuse or circuit breaker at a panelboard is always an acceptable disconnecting means if
The panelboard is in sight of the appliance.
Generators are either small portable models or large permanently installed models.
The portable models usually produce between 3,000 and 10,000 watts peak power and are intended to provide power for essential systems such as heat, a well pump, and refrigeration. The permanently installed models usually produce from 7,000 to over 22,000 watts peak power and are intended to provide power for most or all of the occupant's electricity use.
Voltage
The pressure of electricity in a circuit, similar to water pressure in a pipe; unit of measure is the Volt.
When the tab between the receptacles is removed
The receptacle can be served by two different branch circuits, or half of the receptacle can be switched and the other half can be permanently energized.
Do not use a smoke pen or other unlisted smoke generating device to test a smoke alarm.
The result could be inaccurate, and the home inspector could damage the alarm.
Short circuit
This event occurs when current flows between conductors in an unintended manner, such as between the hot and neutral conductors.
A modern wind turbine functions by capturing wind energy using a rotor (blades similar to an airplane propeller) which rotates a shaft which is connected to an electric generator.
The rotor and generator are mounted on a tower that is tall enough so that the rotor blades are at least 30 feet above obstructions such as buildings and trees within 300 feet. System electrical output can range from 20 watts to 30,000 watts or more, depending on wind speed and generator capacity.
Wind turbine systems have similar types of components and requirements as a solar PV system.
The rotor and generator module, previously discussed, takes the place of the solar arrays.
The IRC requires updating smoke alarms and carbon monoxide alarms to current standards when work requiring a permit is performed.
The smoke alarm update exceptions involve exterior work such as roof coverings and wall claddings, and work involving only plumbing and mechanical systems.
Basements, attics, and crawl spaces should have at least one light if the space is used for storage, or if it contains equipment that requires service.
The switch should be near the entrance to the space. The light may be located anywhere in the space except the light should be near the equipment, if any. The light may be a pull chain type if the light is located near the entrance to the space.
The term subject to physical damage is often used regarding electrical components.
The term is undefined, and as such is subject to interpretation.
Most exterior stairways should have a light near
The top landing.
Transformer
The transformer is the source of electricity in most homes belonging to the utility
Two types of PV systems exist.
The two types are grid-connected (also called grid-tied and utility-interactive) and stand-alone. Within these two types are several possible configurations.
It is usually not possible to identify the smoke alarm type by looking at it from below.
The type is usually on the back and requires removing the alarm from its mounting bracket to identify its type.
Grid-connected systems are connected to
The utility electricity grid and are intended to provide some or all of the occupant's electricity needs during daylight. The occupants rely on the utility to provide electricity in excess of the system's capacity, on cloudy days, and at night.
Light fixtures that weigh more than six pounds should be supported by a box listed for support of heavier light fixtures.
These boxes should be secured directly to framing or should be secured to metal bars that are secured to framing.
Boxes used to support ceiling fans should be labeled as suitable for ceiling fans.
These boxes should be secured directly to framing or should be secured to metal bars that are secured to framing. Ceiling fan support is usually concealed.
Receptacles installed in wet areas should have a cover that is weatherproof when a plug is inserted.
These covers are sometimes called bubble covers.
Receptacles installed in damp areas should have a cover that is weatherproof when a plug is not inserted.
These covers have a cap that snaps shut over the receptacle when the receptacle is not in use.
Switches installed in wet and damp areas should have a cover that is weatherproof.
These covers have a cap that snaps shut over the switch.
A separate disconnecting means should be installed if the panelboard is not within sight of the appliance.
These disconnecting means usually consist of a switch, a fuse block, or a pull tab inside an enclosure located near the appliance.
Several other switch types are available.
These include multiple switches in one device and a switch and a receptacle in one device for installation where space is insufficient for individual switches.
Some houses built in the 1960s and 1970s have low-voltage switches that activate 120 volt light fixtures.
These low-voltage switches connect to an enclosure full of relays located in the attic, or sometimes in the garage.
At least one GFCI protected receptacle should be installed in any accessory building that is provided with electricity.
These receptacles are in addition to receptacles required for appliances such as HVAC and laundry appliances.
Toggle switches containing mercury were popular in the 1960s and 1970s
These switches can be identified by their silent operation. These switches are considered hazardous waste.
Programmable switches and timer switches are available.
These switches usually have a manual override that allows the home inspector to test operation of the light fixture.
Many, if not most, metals we use every day are not pure forms of the metal.
They are a combination materials called an alloy.
Generators are usually intended to provide electricity to the house if the utility electricity is interrupted.
They may provide all or some of the electricity to off-the-grid houses.
Stand-alone solar systems are not connected to the utility grid.
They may provide electricity to one or a few loads.
Receptacles may not be more than 66 inches above the floor if
They serve as a required receptacle.
Exterior receptacles should be installed where
They will not be subject to flowing water, but no minimum height is specified.
Switches should be installed so that ON is in the up position.
This does not apply to 3-way and 4-way switches and to switches normally operated horizontally or by rotation.
Most solar photovoltaic (PV) systems use traditional solar cell panels.
This technology has been available for over fifty years. Newer thin film technology allows solar cells to be integrated into building materials such as roof coverings.
Another solution to solid-conductor aluminum wiring is the COPALUM connector.
This uses a patented connector and crimping tool to cold weld copper wire to aluminum wire.
Metal face plates should also be connected to the EGC.
This usually occurs through the screws that attach the face plate to the receptacle or switch.
One problem with aluminum expanding more than copper when the wire gets hot was that expansion and contraction caused the wire to work loose at connections.
This was especially true for receptacles and switches connected from the back instead of using the side screws. Loose connections equal higher resistance and arcing.
Light fixtures should be securely attached to whatever mounting components are used, and
Those mounting components should be securely attached to framing.
There are currently about nineteen different NEMA standard receptacle types that might be found in a house, excluding
Those used in 3-phase electrical service.
The alarm will not activate if the sensor is not functioning and pressing the test button may not test the sensor.
Thus, pressing the test button does not insure that the alarm will function as intended under actual fire or carbon monoxide conditions. It is critical that the home inspector inform the clients about this distinction if home inspector tests the smoke alarms and carbon monoxide alarms and reports the test results.
Early switches included various types of rotary switches (1920s and before), push button switches (1920s-1940s), pull chain switches, and toggle switches (1930s to present).
Toggle switches are the ancestors of the modern snap switch, the type with a small handle.
Track lights should be installed according to manufacturer's instructions using parts made for use with the track lighting system.
Track lights should not be installed in wet or damp locations, where they could be subject to physical damage, and through walls.
Single phase electricity has
Two energized conductors.
Cable
Two or more conductors encased in sheathing; examples include non-metallic sheathed cable (often referred to by the brand name Romex) and armored cable (often referred to by the brand name BX).
The usual burial depths are:
UF and MC: 24 inches, RMC and IMC: 6 inches, PVC, LFMC, and LFC: 18 inches.
Unbalanced blades can cause the fan to wobble and place more load on the box and other connections.
Unbalanced ceiling fans are a reportable defect.
Covering knob and tube with thermal insulation is a bad idea, but not for the reason many believe.
Under normal operating conditions, knob and tube covered by thermal insulation should not overheat more than any other wiring method. Thermal insulation-covered knob and tube may be damaged by attic traffic. Carelessly installed thermal insulation may push the wires too close to framing and other surfaces.
Wall space includes any wall more than 2 feet wide, fixed panels of doors, partial height walls, and room dividers such as railings.
Wall space does not include obstructions such as fireplaces and closets.
Modern NM jacket is color-coded to identify the wire gauge.
White = #14, Yellow = #12, Orange = #10, Black = #8 and #6.
Wind consistency and speed are the important environmental components in determining whether a wind turbine is practical.
Wind speed is assumed between 24 and 26 miles per hour when rating the electricity output of wind turbine generators. An average wind speed of at least 10 miles per hour is a recommended minimum.
Modern wind turbine electricity generating systems are the direct descendants of
Windmills that have been used for hundreds of years for applications such as pumping water and grinding grain.
Home inspectors should inspect inside disconnecting means enclosures that have fuse blocks and pull tabs.
Wiring defects such as damaged conductors and improper taps to serve other outlets are not common but can occur.
A multiwire branch circuit is a three wire branch circuit
With two hot (ungrounded) wires and one neutral (grounded) wire.
A GFCI protected receptacle should be installed within 78 inches vertically from a deck, balcony, or porch that is
accessible from inside the house; this receptacle is addition to the required at-grade receptacle.
Electricity is generated
as three phase, and is converted to single phase for almost all residential electrical systems.
Receptacles are not required behind sinks and cooking appliances unless
the countertop behind the sink or appliances is deeper than 12 inches.
At least one GFCI protected receptacle should be installed within 78 inches vertically from
the walking surface (grade) at both the front and rear of the house.
One characteristic of houses built when knob and tube was popular was a lack of (or minimal)
thermal insulation.
Common sizes for PVC range from
½ to 6 inches diameter.
Solar water heating system components include:
• A collector, • A storage tank (may be the collector in a batch system), • Insulated pipes, • A temperature limitation system to limit the temperature of fluids entering or exchanging heat with a pressurized vessel inside the building to not more than 180° F, • Valves to isolate the solar water heating system from the rest of the domestic hot water system, • A backflow preventer, • Labels as required by local standards.
Other components of a PV system include:
• Conduit, electrical metallic tubing (EMT) and metal-clad cable (MC) are common, but other types of conduit and tubing may be acceptable if listed for use where installed; conductors should be run in conduit except where entering or leaving equipment or when necessary to allow movement of an array, • Conductors, may be single conductors or multiple conductor cables if listed for use where installed, • Mounting hardware appropriate for the modules installed, • Waterproofing components where components penetrate roofs and walls.
Common light fixture types include:
• Flush-mounted ceiling fixtures that are installed flush against the ceiling • Hanging fixtures (e.g., chandeliers and pendants) that hang from the ceiling by a chain, rod, or cord • Wall-mounted fixtures (sometimes called sconces) • Recessed fixtures (sometimes called can, high-hat, or pot lights) that are installed into holes in the ceiling • Track lights that are installed in a metal strip that is usually attached to the ceiling • Various types of under-cabinet fixtures that are usually for task lighting of kitchen countertops • Other specialty light fixtures, such as cable lights, are also available.
Other PV system requirements include:
• PV conductors should be identified as such where accessible • PV conductors should not be installed in the same conduit or tubing as conductors from other systems, except where the PV conductors connect to other systems • Conduit, tubing, and boxes containing PV conductors should be labeled as such, this is a newer requirement so older systems may not comply • Exposed non-current-carrying metal parts of the PV system should be grounded • At least two 36 inch wide pathways should be provided on separate roof planes for access by emergency personnel, at least one of these should be on the street side, this is a new requirement so most systems will not comply • Arrays should be set back from a roof ridge either 18 or 36 inches depending on how much of the roof area is occupied by arrays, this is a new requirement so most systems will not comply.
The most common alternative energy systems likely to be found at residential structures include:
• Solar photovoltaic (PV), • Wind turbines, • Solar water heating, • Passive solar design, • Ground-source heat pumps (commonly but inaccurately called geothermal systems), • Water-source heat pumps.
Light bulbs (lamps) come in five common types.
• Thomas Edison invented the incandescent bulb, so it has been around since the beginning. Incandescent bulbs are inefficient, and are being phased out by law. • Compact fluorescent bulbs (CFLs) are one new type of energy efficient bulb. Complaints about CFLs include that some take time to emit the full light output and that they contain mercury, a hazardous material. • Light emitting diode bulbs (LEDs) are another energy efficient bulb. The primary complaint about LEDs is high cost; however, cost is decreasing and these bulbs are said to last for up to twenty years. • Fluorescent bulbs have also been around for a long time. They are usually straight tubes, but are available in U and circular shapes. Fluorescent bulbs require a burst of energy from a component called a ballast to start working. The primary complaint about fluorescent bulbs is what some consider the harsh or unnatural light. • Halogen bulbs are similar to incandescent bulbs, but are more energy efficient. Halogen bulbs can produce significant heat and can burn out quickly in light fixtures that cannot dissipate the heat. Halogen bulbs usually require a special socket, so only a Halogen bulb may be used in the fixture.
Require bonding
• Water and gas distribution pipes • Electrical conduit • Electrical equipment cabinets and cases • Framing and sheathing • HVAC ducts • All metal parts of the electrical service and distribution systems.
