7) Electrical Systems
true or false? A fused 200-amp service has two 100 amp fuses in the service box.
false
what is a reliable way to identify the service size?
the service entrance conductor size.
what does the term "double tapped" mean?
two wires are connected to a single terminal.
are service laterals overhead or underground?
underground
describe how you would test a GFI receptacle during an inspection.
use a circuit tester and operate the test button on the receptacle
can an outlet be protected by a ground fault interrupter without it being a apparent?
yes, all outlets downstream of a GFI outlet will be protected.
list five common branch circuit wire problems.
1. damaged 2. not well secured 3. loose connections 4. open splices 5. wires to close to ducts, pipes, vents, chimneys and flues 6. wires to close to the edge of studs or joists 7. wires run through steel studs without protection 8. exposed wires on walls or ceilings 9. exposed wires in attics 10. cable used Outdoors 11. buried cable not rated for buried use 12. household wire used as extension cords 13. under-sized wire 14. improper color coding 15. abandon wire
list seven common junction box problems.
1. damaged 2. missing 3. loose 4. not grounded 5. cover loose or missing 6. crowded 7. concealed boxes
what would two wires usually mean at a service drop?
120 volts service
the most common wire size for branch household circuits is _____ gauge.
14 gauge
what size wire is found on most general-purpose outlets for lights and receptacles?
14 gauge
overhead power lines within 10 horizontal feet of any portion of a diving board or platform must be a minimum of _____ feet above the highest standing area of the diving board or platform.
14.5 feet
how many wires would you typically find in a 240 volt service drop?
3
list four common areas of water penetration into service entrances.
1. conduit joints 2. mast head 3. roof flashing 4. meter base 5. house entry
list four common problems with knob-and-tube wiring.
1. connections not in boxes. 2. brittle wire, insulation, or sheathing. 3. wire buried in insulation. 4. fused neutrals.
does knob-and-tube wiring have a ground wire associated with it?
No
what are the implications of oversized Breakers?
Wires can overheat without tripping the breakers.
what is meant by open splice?
a connection that is not made inside a junction box
a grommet is _______.
a fitting that protects a cable from the sharp edges of steel studs
why should heat lamps not be located over doors?
a towel thrown over the door can be ignited by the heat lamp
what is the definition of a volt?
a volt is the measurement of the force or potential energy in an electrical system (V=IxR)
what is a brief definition of a watt?
a watt is a measure of the current of electrical energy being consumed or released (P=VxI)
wire should be _______ inches away from the edge of studs.
one and a quarter inches
is the service drop overhead or Underground?
overhead
abandoned wire should be _______.
removed
the grounding systems are connected to the house neutral at the________.
service box.
pool equipment utilizing a cord to connect to a power source must be plugged into a _______
single outlet receptacle that uses a twist-lock device.
the grounding electrode conductor may also be called________.
the grounding electrode conductor is the ground wire.
the grounded service conductor is called?
the neutral
all power cords for pool equipment should be properly sized for the equipment they serve, but no case can they be less than #_____ AWG copper.
#12 awg copper wire
a copper wire of at least # ____ AWG must connect the structural rebar within the pool structure and deck, wet Niche fixtures of underwater lighting, slides, diving boards, ladders, pumps and their Associated equipment, and any other exposed metal apparatus within 5 feet of the pool walls.
#8 AWG wire
describe three different cable types you might see.
1. NM (non metallic), Romex, Loomex 2. UF (underground feeder) 3.BX (AC-90), armored cable 4. knob-and-tube
list 14 common receptacle problems.
1. damaged 2. loose 3. overheating 4. ungrounded Outlets 5. open neutral or open hot connections 6. reverse polarity Outlets 7. inoperative 8. wrong type receptacle 9. no GFIS 10. overheated neutral on split receptacles 11. broken pin or blade and slots 12. not enough receptacles 13. Warren receptacles 14. too far from basin
list 10 common problems with service entrance conductors.
1. No drip loop 2. No mast head 3. Mast head not weather tight. 4. Mast or conduit bent. 5. Mast or conduit rusted. 6. Mast rotted (if wood). 7. Mast conduit or cable not well secured. 8. Mast conduit or cable not weather tight. 9. Conduit or cable not well sealed at house/wall penetration. 10. Cable frayed, damaged, or covered by siding.
describe how knob-and-tube wiring is visibly different from modern cable.
1. The black and white wires are separate and run in pairs. 2. Ceramic tubes protect the wire as it runs through joists or studs. 3. Ceramic knobs are used where wire changes direction.
how would you identify aluminum wiring?
1. The conductor is silver colored. 2. The sheathing usually has the word ALUMINUM, ALUM, or AL.
list service drop clearances above ground, swimming pools, and roofs.
1. above roadway -- 18 ft 2. above driveway -- 12 ft 3. above flat roof -- 8 to 10 ft 4. above sloped roof -- 18 inches 5. away from water in swimming pool 22-1/2 ft in any direction. 6. 3 ft above sloped roof with pitch greater than 4/12 7. above walkway -- 10ft
list three common problems found with aluminum wiring.
1. connectors not compatible with aluminum. 2. no antioxidant grease on stranded wires. 3. overheating.
list two different branch wire materials you might see.
1. copper 2. aluminum
give four examples of damaged wire.
1. cut or pinched 2. chewed on by animals 3. burned wire 4. wire with griddle or cracked insulation
list four common problems found with switches.
1. damage 2. loose 3. overheating 4. inoperative
list 7 common lighting problems found in houses.
1. damaged or loose 2. overheating 3. poor stairway lighting 4. conventional lights used in wet areas 5. improper recessed lights 6. improper closet lighting 7. isolating links needed on pull chains
the functions of Earth grounding systems include_______.
1. grounding systems can help dissipate electricity from lightning. 2. grounding systems can help avoid the buildup of static electricity.
list five destinations where ground wires can terminate.
1. metal water supply pipes. 2. metal rods driven into the ground. 3. wires buried in the footings of buildings (UFER ground). 4. buried grounding plates or rings. 5. the frames of metal buildings (not common houses). 6. metal well casings.
list four common problems found only with breakers.
1. multi-wire circuits not linked. 2. too many breakers 3. wrong breaker in panel 4. loose breakers
list 12 common problems found with grounding systems.
1. no grounding. 2. ground wire attached to plastic pipe. 3. ground wire after meters and valves with no jumper. 4. spliced ground wire. 5. poor connection. 6. ground connections not accessible. 7. ground rod cut off. 8. corroded ground rod. 9. under-sized ground wire. 10. neutral bonded to ground wire after service box. 11. neutral wires not bonded to ground wire at service box. 12. service box not bonded to ground wire. 13. no ground in subpanel feeder wires.
list 14 conditions that may be found in all panels.
1. obsolete/fused neutrals 2. damaged panel or components 3. loose or missing door 4. openings in panel 5. panel too small 6. overheating 7. rust or water in panel 8. circuits not labeled 9. panel crowded 10. poor access 11. upside down 12. not suitable for aluminum wiring 13. poor location 14. exterior panel not weather tight
list seven common problems with service drops.
1. overhead wires too low. 2. damaged or frayed wires. 3. trees or vines interfering with wires. 4. wires to close to doors or windows. 5. wires not well secured to the house. 6. poor connection between service drop and service entrance. 7. inadequate clearance from roofs.
list 16 common conditions you might find in a service box.
1. poor access or location. 2. loose. 3. rust or water in box. 4. unprotected opening. 5. damaged parts. 6. overheating. 7. incorrect fuse or breaker size; box rating too small. 8. service entrance wires exposed in the house. 9. poor connections. 10. illegal taps. 11. neutral wire by-passes service box. 12. fused neutral wire. 13. fuses upstream of a disconnect switch. 14. obsolete box. 15. exterior box not weather tight. 16. box not rated for aluminum.
list two functions of the drip loop.
1. prevents water entry into the conduit or service entrance conductors. 2. shows that the service drop wires are not straining the splices
distribution panels are also called (list six other names if you can) ________.
1. service panels 2. panelboards 3. auxiliary panels 4. sub panels 5. fuse boxes 6. fuse panels 7. breaker panels
list six problems found with wires in panels.
1. sheathing not removed 2. overheating 3. loose connections 4. damaged 5. not well-secured 6. wires Crossing bus bars 7. abandoned wires in the panel
list three methods for screwing wire ends.
1. terminal screws 2. push in connectors 3. solderless connectors
listed, manufactured, self-contained portable spas and hot tubs May utilize a cord no greater than _____ feet in length.
15 feet.
what is the maximum amperage rating for corded pool equipment?
20 amps.
roughly 999 out of 1000 houses have ______ volts available
240
what is the maximum cord length permitted for corded pool equipment?
3 feet.
As a general rule, the area _____ inches wide and _____ feet in front of the electrical cabinet should not be obstructed.
30 inches wide and 3 feet in front.
what is the largest single phase service that you are likely to find in a home?
400 amps
No lighting or paddle fans may be installed over the water or in an area extending less than ______ horizontal feet from a pool wall, unless it is _____ vertical feet, or higher, above the water.
5 ft unless it is 12 vertical feet, or higher, above the water.
all electrical switches must be greater than _______ horizontal feet from pool walls.
5 horizontal feet.
all pool heaters, as well as, pumps or blowers with driver motors in excess of 1/8 horsepower, require a service disconnect within ______ feet of, on the same wall as, and within a direct line of sight from the equipment.
50 feet.
GFCI convenience receptacle must be installed no higher than _______ above grade or desk.
6 ft 6 in
how far should wires be kept away from the metal vent connector on a gas Appliance?
6 in
all electrical junction boxes must be at least _____ inches above the highest possible water level, no less than ____ inches above the deck and no closer than _____ horizontal feet from the pool wall.
8 inches above the highest possible water level, no less than 4 inches above the deck. No closer than 4 horizontal feet from the pool wall.
what size of copper wire would you expect to find on the service entrance for: A. a 60-amp service? B. a 100-amp service? C. a 200-amp service?
A. 6 gauge B. 4 gauge C. 2 - 0 gauge
Lighting fixtures installed between _____ and _____ horizontal feet from a pool wall require GFCI protection if installed less than _____ vertical feet above the maximum water level.
Between 5 and 10 horizontal feet. Less than 5 vertical feet above the maximum water level.
Power lines over the water and any area extending _____ horizontal feet from the pool walls, or the edge of the base of any diving board, or platform must be at least _____ feet above the water level or the base of the diving board or platform.
Extending 10 horizontal feet. Must be at least 22.5 feet above the water level or the base of the diving board or platform.
all 120 volt pool equipment, 240 volt single phase pump motors, outdoor receptacles (regardless of distance from the pool) and underwater lighting circuits, also require _______
GFCI protection
what is the difference between insulation and sheathing?
Insulation is around individual wires; sheathing forms the cables by wrapping around the insulated wires.
what is the advantage of a 240-volt circuit?
More electricity can flow at lower amp ratings
should the neutral and the ground wires be bonded together at the sub panel?
No. Because electricity may flow through the ground wire under normal circumstances. The ground wire should be reserved for emergency situations.
does pool equipment plugged into receptacles located greater than 10 feet from the pool wall require a single outlet receptacle or a Twist lock device?
No. Greater than 10 ft does not require a single out or twist lock device.
explain why fused neutrals are a bad idea.
Only the fuse on the neutral side blows. The circuit may not work, but there may be voltage throughout the entire circuit.
explain the problem with reverse polarity.
The collar of a light fixture may be energized, increasing the risk of electrical shock when changing a light bulb.
what is the implication of a panel that is too small for the service?
The panel may overheat
what is a split receptacle?
The top part of the outlet is on one circuit and the bottom part on a different circuit.
what size copper wires are adequately protected by: a. 15 amp Breakers? b. 20 amp Breakers? c. 30 amp Breakers? d. 40 amp Breakers?
a. 14 gauge (15 amp breaker) b. 12 gauge (20 amp breaker) c. 10 gauge (30 amp breaker) d. 8 gauge (40 amp breaker)
what caused the problems with aluminum wire? (list at least 3 things)
aluminum wire--- 1. tends to creep out from under terminal screws. 2. forms corrosion (oxide) that is an electrical insulator. 3. is softer than copper and easier to damage when working with the wire. 4. was, in some of the early material, a low-quality wire prone to weakness and breaking.
when was aluminum wire used (in branch circuits)?
aluminum wiring was used from the mid-1960s to the late 1970s
what is a brief definition of an amp?
an amp is a measure of how much electrical current is flowing (I=V/R)
what is the definition of an ohm?
an ohm is a measure of resistance to electrical flow in a conductor or insulator (R=V/I)
where is the antioxidant grease typically used?
antioxidant grease is typically used on stranded aluminum wires.
how far should wires be kept away from heating ducts or pipes?
at least one inch
which of the following is a safety concern? a. a fuse that is too small. b. a fuse that is too big.
b. A fuse that is too big.
what is the problem with running wire across the top of the attic ceiling joists?
because they are not visible and may be stepped on.
true or false? All junction boxes should be concealed.
false
true or false? If you can't read the size of the fuses in the service box, you should remove them to try to get a better look.
false
true or false? Load calculations are part of a home inspection.
false
true or false? One smoke detector is needed in each room, near the kitchen because that's where most house fires start.
false
true or false? Sub-panels must be immediately adjacent to the main panel.
false
true or false? The drip loop is typically a part of the service drop.
false
true or false? The drip loop should be as close to the roof surface as possible.
false
true or false? There can be up to 10 throws to disconnect all of the electricity in the house.
false
true or false? Typical distribution panels have 60 circuits.
false
true or false? Wires run directly from the service box to the branch circuits.
false
true or false? You are allowed to ground to the gas piping.
false
true or false? all service entrance conductors must be attached above roof level.
false
true or false? all service entrance conductors must be in conduit.
false
true or false? the wire size for the service drop must be the same as the wire size for the service entrance conductors.
false
the service entrance conductors run from the _______ to the______.
from service drop to the service box.
how should the feeder wires to a sub panel from the main panel ideally be protected?
fuses should be provided at the main panel.
No service receptacle may be installed less than ______ horizontal feet from pool walls (no less than _____ horizontal feet from the walls of spas and hot tubs.)
less than 10 horizontal feet from pool walls. No less than 5 horizontal feet from the walls of spas and hot tubs.
what is meant by "linking" in multiwire Branch circuits?
linking means that the fuses or breakers for multiwire branch circuits have to be shut off in pairs.
wires should not be run on wall surfaces without ________.
mechanical protection
all 240-volt pool equipment must be______, and each requires a separate dedicated _______.
must be grounded, and each requires a separate dedicated circuit.
At least one GFCI protected convenience receptacle is required, no less than ______ feet and no greater than _____ feet from swimming pool walls (not less than ______ feet nor greater than ______ feet from the wall of a spa or hot tub)
no less than 10 ft and no greater than 20 ft. (not less than 6 ft nor greater than 10 ft for spa or hot tub.)
implications of an undersized service include
nuisance tripping of the main fuse or breakers
roughly 999 out of a 1000 houses have ______ service entrance wires.
three
what would 4 wires mean at the service drop?
three phase electricity.
from the point where the ground and the neutral wires connect, there are two paths to ground. What are they?
through the neutral service wire or through the grounding electrode conductor to water pipes or ground rods.
true or false? Aluminum is an acceptable service entrance conductor material.
true
true or false? Knob-and-tube wiring was commonly installed without junction boxes.
true
true or false? Outlets should be close to basins.
true
true or false? The service box can be inside, outside or in the garage.
true
true or false? The service box may stand alone or may be combined with the distribution panel.
true
true or false? if the main fuses have a higher rating than the service entrance wire this is a safety issue?
true
true or false? service entrance conductors run from the service drop to the service box or service panel.
true
true or false? the red and black wires of multi wire circuits should be on separate bus bars.
true
true or false? the service size is determined by the amperage and voltage ratings of the service.
true
how are lights tested?
turn them on and off by the switches
do we normally shut off the power when looking at an electrical system in the house? Why or why not?
we do not shut off the power. This would be a significant inconvenience to the occupant.
enclosures for receptacles used to power corded pool equipment must be suitable for_______?
wet locations, and be of the type that is whether protected, with or without the cord in place.
A single receptacle twist lock device is required for pool equipment that is plugged in when the outlet is located _____ horizontal feet from a pool wall
whenever the outlet is located less than 10 horizontal feet from a pool wall. Such Outlets are not permitted less than 6 horizontal feet from a pool wall.
what are the issues on running wire through steel studs?
wire may be damaged by the sharp edges of the steel studs. Wires passing through holes should be protected with grommets, for example. Wires running parallel to studs should stand off the studs.