Residential Electrical inspection

Service 110 Amps

#1 Aluminium, #3 Copper

Service 100 Amps

#2 Aluminium, #4 Copper

The inspector should pay special attention to the following questions and report any deficiencies as in need of immediate repair:

1. Does the breaker exceed the capacity of the conductor? 2. Does the breaker have multiple incorrect "taps"? 3. Do the 240-volt breakers have their handles tied properly? 4. Do the GFCI breakers test and reset properly? 5. Do the AFCI breakers test and reset properly? 6. Is there any sign of overheating, arcing or smoke damage on any of the breakers?

Rigid Conduit:

1. EMT/thin-wall: this is Electrical Metal Tubing, which can be bent to shape for installation. 2. RMC/thick-wall: this is threaded Rigid Metal Conduit, where any changes of direction require angled fittings. 3. RNC/PVC conduit: often referred to as Schedule 40 or 80 plastic, this gray-colored Rigid Non-metallic Conduit is very common in newer construction, but should not be confused with white or ivory-colored PVC piping, which is not rated for electrical use.

Inspecting distribution panels

1. How is the service grounded back to the service panel? 2. Are the neutrals and grounds separated? 3. Is the neutral bus isolated from the panel enclosure? 4. Is the panel enclosure connected (bonded) to the grounding bus? 5. Does each neutral conductor terminate at a separate lug on its bus?

All cables, cable assemblies and conduits need regular support from the structure. The basic specifications for supports are:

1. NM/Romex® cables: stapled within 12 inches of metal enclosures or 8 inches from plastic gang boxes, and every 4 feet and 6 inches of run length. 2. AC cables: stapled within 12 inches of metal enclosures, and every 4 feet and 6 inches of run length. MC cable has a run-length that is extended to 6 feet between the required supports. 3. metal conduit/EMT: clamped within 36 inches of enclosures, and every 10 feet of run length.

Service 125 Amps

1/0 Aluminium, #2 Copper

Wires to outlets

Branch circuit conductors

Main disconnect

Service disconnect

Main panel

Service or distribution electrical board with a service disconnect

Edison Base Screw Fuse Panels

These are the fuses that screw into many older panels and have the same thread that Edison used for other applications, such as the common light bulb. This obviously creates a problem, since a higher-amperage fuse can be screwed into a location supporting lower-amperage conductors, effectively turning the conductor into the fuse. The inspector should recommend the installation of S-type fuses and adapters to ensure that the circuits cannot be overloaded.

Hot or live wire

Ungrounded conductor

Sub-panel

distribution panel board without a service disconnect

Before even thinking about touching, inspecting or removing a dead front cover, the inspector should

look carefully for signs of water or moisture staining on the panel or on its surrounding wall. If there is any evidence of water, the inspector should recommend that the panel be fully evaluated and repaired by an electrical contractor, so delving further into the panel is not only potentially dangerous, it's also unnecessary.

copper: absolutely the best conductor in common use, as it has low electrical impedance, so a relatively small conductor can deliver a lot of power over long distances without too much power loss or heat generation.

tinned copper: still sometimes seen on older properties. Copper is tinned for two reasons: to aid soldering; and to stop the copper from reacting with old rubber insulation.

When evaluating a elecrical supply

we need to recognize that copper and aluminum conductors are not the same, copper inherently has less resistance to the flow of electrons than aluminum does. For this reason, aluminum conductors are always one to two sizes larger than the equivalent copper one for any given amperage

Voltage

= Pressure = Volts = E

All connections in conductors need to be made in approved enclosures, typically panelboards, junction or J-boxes, and gang boxes which is what is behind switches and receptacles.

All enclosures and J-boxes should also have proper cable connectors where the conductors enter the box. Plastic gang boxes do not require these, since strain relief is built in.

Aluminum branch circuit:

Aluminum will generally become defective faster than copper. Poor connections cause wiring to overheat, creating a potential fire hazard. In addition, the presence of single-strand aluminum wiring may void a home's insurance policies. Inspectors may instruct their clients to talk with their insurance agent about whether the presence of aluminum wiring in their home is a problem that requires changes to their policy's language.

Panel cover

Deadfront

Earth or ground wire

Equipment grounding conductor

While electrical splices in panels are not in and of themselves improper, the home inspector should bear in mind that, like double taps, they are the line of least resistance and often done by unqualified persons. Generally untidy panel wiring, double taps, lots of splices, and wire nuts are indicative of homeowner wiring, which probably requires further evaluation.

Occasionally, the inspector will open a panel and see most or all of the neutral conductors fried. This may have been caused by the property having been struck by lightning. The neutrals will be most affected by this, since they are, of course, connected to the grounding system.

Before exploring these protocols, we must understand how receptacles should be correctly wired. 1. small slot: is the hot or ungrounded supply; 2. large slot: is the neutral or grounded return; and 3. round pinhole: is the grounding conductor. This is very important if the receptacle has reversed polarity (hot and neutral switched) because then things like lamp holder collars may become live and pose a great electrocution hazard. It is very common to find 3-prong receptacles with no ground, or, worse, receptacles with a false or bootleg ground where the grounding terminal has been illegally connected to the neutral.

Some inspectors are now starting to check voltage drop along conductors. This falls well outside of industry standards of practice, but with electrical components becoming ever more sensitive to voltage fluctuations, many more inspectors will start to check for this. The National Electrical Code® recommends that voltage should not drop more than 3% on branch circuits, and a 5% overall drop, including the service itself.

Zinsco-Sylvania Panels

The earliest Zinsco panels had busses made of copper bars and were very reliable. However, during the copper shortages of the mid-1960s, the copper was replaced with anodized aluminum bars. This led to problems of poor contact between the breaker and the bus bar, and many have failed since due to arcing between the components. The problems continued after Zinsco's sale to Sylvania in the early 1970s.

The home inspector should check the following conditions on a representative number of receptacles: 1. no power present; 2. no ground; 3. open neutral; 4. reversed polarity (hot and neutral); and 5. reversed ground and hot.

The inspector may also choose to invest in equipment to enable him to report on: 1. low resistance grounds; 2. bootleg grounds; 3. true voltage; and 4. voltage drop.

Amps

The rate at which electricity flows through a conductor. I=W/E

In newer homes' bathrooms, outlets are required to be on dedicated 20-amp, GFCI-protected circuits, and at least one receptacle is required to be installed within 3 feet of any vanity basin. The home inspector is justified in suggesting that non-GFCI receptacles in older bathrooms should be upgraded for safety reasons.

There must be a minimum of one 20-amp circuit within 6 feet of the appliance location. Dryer outlets will be covered in the 240-volt section, but they should have a 4-wire, 30-amp minimum supply.

Pushmatic Panels

These are still fairly common. The breakers are of a "push-for-on," "push-again-for-off" design. The issues with these tend to be: 1. lack of panel capacity; 2. sticking breakers; and/or 3. difficulty finding replacement parts.

Panel access

They should be on a free wall space not less than 30 inches wide, have a clear 36 inches of space in front of them, and have 6 feet and 6 inches of head room. In older homes, it is also common to find electrical panels inside closets. This is no longer acceptable in new construction. Similarly, service disconnects and remote distribution panels are not allowed in bathrooms.

Ohms Law

are basically a series of mathematical models that show us how to work out safe working loads for conductors and electrical components.

how many conductors does a 120/240 service drop have?

on a typical 240/120-volt service drop, we will have two ungrounded conductors and a single grounded conductor.

what 4 categories do circuit breakers fall into?

1. 240v double breakers 2. 120v single breakers 3. AFCI breakers 4. GFCI breakers

Inspecting Service Panels

1. Are the neutral and ground connected (bonded)? 2. Is the panel enclosure connected (bonded) to ground? 3. Does each neutral conductor terminate at a separate lug on its bus?

According to InterNACHI's Home Inspection S.O.P., the inspector is not required to:

1. measure or determine the amperage or voltage of the main service equipment; 2. remove panelboard cabinet covers or dead fronts; 3. insert any tool, probe or device into the main panelboard, sub-panels, distribution panelboards, or electrical fixtures; or 4. operate any electrical disconnect or over-current protection devices.

warning signs that a panel, box, or the system in general may be compromised,

1. scorch marks on the dead front or the panelboard door, indicating a past or recent arc flash; 2. rust, which indicates past or recent moisture intrusion; 3. missing or open breakers that cannot be confirmed to be de-energized; 4. overloading of the circuits with DIY wiring; 5. uninsulated wiring; 6. excessive dust, dirt and debris inside the panelboard; and/or 7. any signs of water inside, around or below the panelboard, which can lead to shock or electrocution.

Fused main disconnects are usually a maximum of

100 amps

50-amp: #6/3 with ground NM 4/4/4/6 AL SER Oven. Cooktop. Range.

100-amp: 3 AWG 1 AWG AL remote distribution panel

The typical electrical service for homes in North America is

120/240

Small conductors commonly seen by home inspectors

15 amps = #14 Copper, #12 Aluminium 20 amps = #12 Copper 25 amps = #10 Aluminium 30 amps = #10 Copper, #8 Aluminium

100-amp 4 AWG 2 AWG AL SE cable

150-amp 1 AWG 2/0 AWG AL SE cable

Service 150 Amps

2/0 Aluminium, #1 Copper

15-amp: #14/2 with ground NM - Lighting circuits and typical general-use receptacles in living area. Dishwasher. Disposal. Refrigerator/freezer.

20-amp: #12/2 with ground NM - Receptacle and switches in kitchen, laundry, bathrooms, and dining rooms. Microwave, Dishwasher. Disposal. Refrigerator/freezer. Hydro massage tub.

Service 250 Amps

300 kcmil Aluminium, 4/0 Copper

Service 200 Amps

4/0 Aluminium, 2/0 Copper

30-amp: #10/3 with ground NM - Water heater. Clothes dryer. Condensing unit.

40-amp: #8/3 with ground NM 6/6/6/6 AL SER Oven. Cooktop. Range.

The minimum size for a listed driven grounding rod is

5/8-inch diameter and 8 feet long stainless steel and copper.

Service 400 Amps

600 kcmil Aluminium, 400 kcmil Copper

Service Panels

A service panel is a distribution or load center that contains the main disconnect. This is the ONLY panel where the neutral and grounds should be joined (bonded) together.

Anti-oxidant paste is a grayish paste that is commonly found on older aluminum multi-strand conductors and is still required by some city electrical inspectors. This paste was designed to stop the aluminum from oxidizing, and thus be better able to maintain a clean contact footprint in its lug.

All abandoned wiring should be removed from the electrical panel, or, at the very least, it should be properly isolated so that the conductors are not able to make contact with any live components.

According to the 2008 NEC, crawlspaces and unfinished basements that have NM cable installed shall be drilled through the joists unless installed on a running board. Cables with three 8-awg or two 6-awg and larger shall be allowed on the surface of the joists.

Although exposed conductors are allowed to run in attics, there are some safety concerns that the home inspector needs to be aware of, especially as the homeowner is going to enter the attic space to store seasonal goods. All conductors should be protected within 6 feet of the scuttle opening. This means that no cables should be run on top of joists in this area. If they run perpendicular to the joist, they should either be drilled through the timbers and have a running board over the top, or be stapled to the side of a running board.

What is an arc flash

An arc flash occurs when a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or to neutral or ground. An arc flash can have various catalysts, including: 1. excess dust; 2. condensation; 3. corrosion; 4. component failure; 5. faulty system installation; 6. dropping a metal tool, which may cause even a small spark; and/or 7. accidental contact.

The inspector will often see homeowner wiring using things like doorbell or speaker wire, and cut-down extension cords supplying circuits derived from the panel.

Any conductor that has been nicked (cut, scratched, incised, or damaged) as the insulation was removed is now of a smaller diameter than intended and has a higher resistance to the flow of electrons.

Bonding components

As discussed in the section on panel enclosures, they need to be bonded to the grounding system. But there is also a very long list of other components that need to be connected to ground, since they have the potential to become energized to electrical faults. These components include: 1. interior water piping; 2. water heaters; 3. around water meters; 4. gas lines; 5. electrical enclosures; 6. electrical raceways; 7. electric outlets or junction boxes; 8. CSST gas piping (manufacturer's compliance); and 9. telephone and cable TV systems. In more modern panels, the bonding connector is required to be through an approved green screw so it is more apparent to both the electrician and the code enforcement officer. However, in many panels, there may be a bonding strap or bonding bar.

Double-tapping is sometimes also called "double taps" or "double-lugging." This is when there are two conductors terminating under a screw or lug which is rated for only one.

As the neutral is also a current-carrying conductor, the neutrals should each be terminated separately on the neutral bus. An inspector will often find signs of arcing and overheating where any multiple conductors share a common lug.

Exterior Wiring: The home inspector should report any exposed wiring at the exterior, especially interior-type wiring, such as Romex® types, which are not rated for exposure to ultraviolet light (sunlight). Also, any exterior conductors should be protected against mechanical damage to a height of 8 feet.

Crawlspace and Basement Wiring: In most jurisdictions, exposed wiring is allowed in basements and crawlspaces. In the northern U.S., we commonly see Romex® conductors unprotected as they leave the panel, and the circuits generally run unprotected on the ceiling joists. Crawlspaces are the same unless a prohibitive condition exists, such as a very damp area; then, exposed cable assemblies are the norm.

Distribution Panels

Distribution panels, or load-side panels, are downstream from the panel containing the main service disconnect(s). In these panels, the neutral and grounds should be separate, and the neutral bus should be isolated from the panel enclosure. The only exception to this is in existing detached structures where no metallic path exists between the structures.

Conductor Protection: All current-carrying wiring needs some form of protection from mechanical damage. Also, the occupants of the home need protection from potential shocks where wires are spliced together.

Exposed Wiring: Obviously, there should be no exposed wiring in the finished or livable areas of the home, but this means that some unfinished areas may have exposed, non-metallic Romex®-type cables.

Service to remote panel

Feeder

Habitable Spaces: All habitable spaces are required to have electrical power and, in new construction, one would expect to see an outlet at every 12 feet of wall space. Even hallways longer than 10 feet are required to have power.

Floor-Mounted Receptacles: Standard wall-type receptacles pose a danger when mounted horizontally in a floor structure. Dirt, dust and any spilled water will affect the outlet, plus children or pets will always play with anything on the floor. Recommend upgrading floor receptacles to the approved type, with special covers.

Minimun apms

For houses serving one family, the ampacity of the ungrounded service conductors shall be a minimum of 100 amperes, 3 wire. For all other installations, the ungrounded conductors should have an ampacity of at least 60 amperes. The ungrounded service conductors should have an ampacity of at least the size of the load served.

Neutral wire

Grounded conductor

Grounding rod

Grounding Electrode

Panel earth ground

Grounding electrode conductor

the difference between grounding and bonding is:

Grounding is a direct connection to the earth to aid in removing damaging transient over-voltages due to lightning. The purpose of bonding is to ensure the electrical continuity of the fault current path, to provide the capacity and ability to conduct safely any fault current likely to be imposed, and to aid in the operation of the over-current protection device.

Electrical power

Is the amount of work that the electrical flow can do. This is expressed as watts or kilowatts (1,000 watts). (W) = E(I)

Current

Is the flow of electrons driven by electromotive force through a given resistance. This is expressed as amps. = Flow rate= Amps = I

All counter spaces wider than 12 inches should have an outlet, and the maximum distance between outlets should be no more than 4 feet. There should also be a receptacle within 2 feet of each end of the counter ends, and from any break in the countertop (such as for a range, refrigerator and sinks).

Islands and peninsulas are also required to have at least one receptacle to serve the countertop space. If the space is not available on the countertop area, the receptacle can be installed below the countertop's surface, which must not be more than 12 inches below the countertop, and not installed under any overhang 6 inches or more from the base of the island or peninsula to the edge of the overhang. No countertop outlets are allowed to be installed face-up in the horizontal surface.

Two-prong receptacles, often found by an inspector in an older home, that are connected to two-wire cables do not have the ground wires, which protect people and electrical devices in case of a fault. It is possible to retrofit a new three-prong or GFCI receptacle into the same receptacle box without any rewiring, as long as the box itself is grounded.

It is permissible to replace a 2-prong ungrounded outlet with a 3-prong GFCI outlet, but it must be labeled as "GFCI Protected Outlet, No Equipment Ground." Even though there is not a grounding conductor, there is still some protection against shock provided by the GFCI.

electrical disconnects require

It is required that the entire electrical supply to the home be able to be shut off with six or fewer moves of the hand.

Service Locations: Any unfinished space that houses serviceable equipment, such as furnaces and air handlers, is required to have not only a light but also a power outlet. This includes attics and crawlspaces.

Kitchen Circuits: All kitchens are required to be supplied by two 20-amp circuits over and above any requirements for dedicated outlets for stoves, etc. These circuits shall not serve any lighting needs. One of these branch circuits should be used for small appliance receptacles no more than 20 inches above the countertop. These outlets must also be GFCI-protected.

Knob-and-tube wiring is so named because of the porcelain fittings used to support and insulate the conductors from the timber components in the home. The knob holds the wire away from rafters and joists, while the tubes are inserted into holes bored though joists and studs to protect the conductor and its rubber insulation. Knob-and-tube wiring was the common method used to wire homes in the United States prior to 1930.

Knob-and-tube is a two-wire system with a hot (ungrounded) and a neutral (grounded conductor) only. No separate ground is used, so all receptacles would have been two-prong only. The home inspector should report any knob-and-tube wiring as in need of further evaluation by an electrical contractor.

Outlet

Lighting and\or receptacle outlet

When dealing with the space behind a corner-mounted sink or counter-mounted cooking unit, the 2008 NEC requires that if such space is less than 18 inches, it is not considered a wall space. If that space is 18 inches or more, it must meet the same spacing requirements previously discussed

Most jurisdictions require dishwashers and waste disposals to be on dedicated circuits. Often, refrigerators are plugged into dedicated outlets, which is allowed by the NEC, to prevent nuisance tripping from installed GFCIs.

Grounding Electrode

Most residential construction requires two separate grounding electrodes in any combination of the following (which need to be at least 6 feet apart): driven rods; 1. metal water pipes; 2. well casings; 3. Ufer grounds - The requirements for Ufer grounds are that they have either 20 feet of #4 rebar, or 4-awg copper wire embedded in at least 2 inches of solid concrete within the footer that is in contact with the earth.; 4. ground plates; 5. steel framing; and 6. ground rings. Gas piping CANNOT be used as a grounding electrode for safety reasons

Non-Metallic Cable (NM): Many people use the name Romex® when referring to type-NM cable. Romex® is a trademarked name that has come into common usage. The earliest NM cables were, in fact, rubber-insulated copper conductors bound together as an assembly, with a woven-cloth sheathing. In type NM cable, conductor insulation is color-coded for identification, typically one black, one white, and a bare grounding conductor.

Originally approved by the NEC in 1928 as replacement for knob-and-tube wiring, it became the most common residential wiring used from the late 1940s, up to the introduction of modern thermoplastic (Romex®) type wiring of the early 1960s. Prior to 1985, standard NM was rated for 60-degree applications, which was increased to 90 degrees and is now marked NM-B.

Wiring in Cabinetry: The home inspector will often see unprotected wiring in under-sink locations, especially supplying waste disposals. If any hard-wired appliances have exposed conductors, they should be protected with metal spiral armoring.

Protection of Wiring Through Studs: In frame construction, all of the home's conductors must be run through the wall stud work to supply the outlets. 1. timber studs: Any cable assemblies closer than 1¼ inches from the front face of the stud need to be protected from damage from drywall screws, and the homeowner hanging pictures, etc. This is achieved by installing a nailing plate on the stud. 2. steel studs: Where NM cable or electrical non-metallic tubing is run through openings in steel studs, protection against penetration is required. A steel sleeve, steel plate or steel clip not less than 1/16" in thickness shall be used to protect the cable or tubing. An opening in the stud requires a plastic bushing to protect the cable from chafing against the steel's raw edge. This protection must encircle the entire opening, and not just the bottom half.

Garages were required to have a minimum of one GFCI outlet, and inspectors may find that they also have non-GFCI receptacles dedicated to appliances, such as door openers and extra refrigerators and freezers. Lighting is also required.

The exceptions that allow dedicated receptacles for specific appliances were removed. Now, all receptacles in garages and unfinished basements must be GFCI-protected, including sump pumps. The only exceptions are for fire alarm and burglar alarm systems, and receptacles outside installed for roof snow-melting equipment.

Newer homes are required to have a minimum of one outlet at the front and another at the rear. These receptacles are required to be weathertight while in use, and GFCI-protected. Non-GFCI outlets are allowed for dedicated single outlets only, such as one will find supplying heater strips in colder climates.

The inspector should visually inspect a representative number of receptacle outlets and report the following: 1. 2-wire-only circuits; 2. damaged or missing cover plates; 3. missing screws; 4. damaged receptacles; 5. signs of overheating on receptacles or surrounding walls; and 6. lack of GFCIs and AFCIs.

Federal Pacific Electrical

The problem with this brand is primarily with their Stab-Lok® range of panels and breakers. These featured stamped sheet metal or copper bus bars and breakers with thin copper tabs that were designed to lock into the bus. These have the unfortunate habit of falling out when the dead front is removed. Federal Pacific panels were subject to warnings issued by consumer protection groups, which include: 1. loose breakers; 2. non-tripping breakers; and 3. arcing problems between the breaker and its bus.

Exterior Flexible Conduit: This is often seen by the home inspector as the supply conduit to outside installations, such as air-conditioning compressors.

This AC/BX-type conduit has a PVC outer sheathing to render it watertight, which should be marked "UF" for exterior use. It is not approved for direct burial, however.

An electrical circuit requires a minimum of

Two wires through which electric current flows. Current is measured in amperes, which travels from a power source (such as the local utility), through the device it operates, called the load, and then back to the source to complete the circuit. In AC or alternating-current wiring, there are about 120 volts in the "hot" or energized wire. This voltage provides the momentum that forces the electrons to flow in the circuit. Most 120-volt circuits are wired to deliver 15 or 20 amps of current.

armored cable (AC): Conductors protected by a spiral-wound outer metal sheathing. AC has been around since the early part of the century, and they gained wide acceptance in the 1930s, especially after the NEC's acceptance in the 1932 Code.

Type-AC cables fall into two categories: those with an internal bonding conductor and those without. In many cases, the sheathing itself, or its internal bond, has been used improperly as the grounding conductor, or, even worse, as the neutral conductor.

aluminum: a good conductor of electricity but has higher impedance to the flow of electrons, which means that larger conductors need to be used for any given amperage. Aluminum was used for residential branch circuit wiring from the mid-1960s to the late 1970s, but was found to be unreliable.

copper-clad aluminum: coating aluminum in copper was an attempt to overcome the issue of oxidization of the aluminum conductors that was leading to failures. It did not have the failures associated with pure aluminum and is considered safe. However, copper-clad should be sized the same as normal aluminum.

Resistance

limits the conductor's ability to allow the flow of electrons, and is expressed in ohms. = pipe size = Ohms =R