Home Inspection Ch. 07: Electrical Systems

Knob and tube wiring was commonly installed without junction boxes. True or False?

True

Outlets should be close to basins. True or False?

True

Service entrace conductors run from the service drop to the service box or service panel. True or False?

True

The service box may stand alone or may be combined with the distribution panel. True or False?

True

What size copper wire would you expect to find on the service entrance for: a. 60-amp service b. 100-amp service c. 200-amp service

a. 6 gauge b. 4 gauge c. 2-0 gauge

What is the problem with running wire across the top of the attic ceiling joists?

they are not visible and may be stepped on

What would 2 wires usually mean?

120 volt service

The most common wire size for branch household circuits is:

14 gauge

What size wire is found on most general purpose outlets for lights and receptacles?

14 gauge

Roughly 999 out of 1000 houses have __________ service entrance wires.

3

List 4 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

Is the service drop overhead or underground?

Overhead

Subpanels must be immediately adjacent to the main panel. True or False?

False

Why should heat lamps not be located over doors?

a towel thrown over the door can be ignited by the heat lamp

What size copper wires are adequately protected by: a. 15 amp breaker b. 20 amp breaker c. 30 amp breaker d. 40 amp breaker

a. 14 gauge b. 12 gauge c. 10 gauge d. 8 gauge

What is the difference between insulation and sheathing?

Insulation is around individual wires; sheathing forms the cables by wrapping around the insulated wires.

When was it used?

from the mid 1960's to the late 1970's.

Wires should not be run on wall surfaces without ___________.

mechanical protection

Where is the anti-oxidant grease typically used?

on stranded aluminum wires

Wire should be _____ inches away from the edge of studs.

one and a quarter inches

Abandoned wire should be ____________.

removed

The service entrance conductors run from the _________ to the ___________.

service drop to service box

Distribution panels are also called: (6)

service panels; panelboards; auxiliary panels; sub panels; fuse boxes; fuse panels; breaker panels

The grounding electrode conductor may also be called __________.

the ground wire

How are lights tested?

turn them on and off by the switches

Describe how you would test a GFI receptacle during an inspection.

use a circuit tester and operate the test button on the receptacle

List 2 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.

The functions of earth grounding systems include:

1. Dissipate electricity from lightning. 2. Avoid static electricity buildup.

Describe 3 different cable types you might see.

1. NM, Romex, Loomex 2. UF 3. BX (AC-90), armored cable 4. knob and tube

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.

List 7 common problems with service drops.

1. Overhead wires too low. 2. Damaged or frayed wires. 3. Trees or vines interfering with wires. 4. Wires too 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 14 common receptacle problems.

...

All junction boxes should be concealed. True or False?

False

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.

List 4 common areas of water penetration into service entrances.

1. conduit joints 2. mast head 3. roof flashing 4. meter base 5. house entry

List 3 common problems found with aluminum wiring.

1. connectors not compatible with aluminum 2. non anti-oxidant grease on stranded wires 3. overheating

Give 4 examples of damaged wire.

1. cut or pinched 2. chewed on by animals 3. burned wire 4. brittle or cracked insulation

List 4 common problems found with switches.

1. damaged 2. loose 3. overheating 4. inoperative

List 7 common junction box problems.

1. damaged 2. missing 3. loose 4. not grounded 5. cover loose or missing 6. crowded 7. concealed boxes

List 5 common branch circuit wire problems.

1. damaged 2. not well secured 3. loose connections 4. open splices 5. wires too close to ducts, pipes, vents, chimneys, flues 6. wires too close to studs or joists 7. wires run through steel studs w/o protection 8. exposed wires on walls or ceilings 9. exposed wires in attic 10. cable used outdoors 11. buried cable not rated for buried use 12. household wire used as extension cord 13. undersized wire 14. abandoned wire

List 12 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

List 5 destinations where ground wires can terminate.

1. metal water pipes 2. metal rods driven into the ground 3. wires buried in the footings (UFER ground) 4. buried grounding plates or rings 5. frame of metal buildings 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 common problems found with grounding systems.

1. no ground 2. ground wire attached to plastic pipe 3. ground wire after meter and valves with no jumper. 4. spliced ground wire 5. poor connection 6. ground connection not accessible 7. ground rod cut off 8. corroded ground rod 9. undersized ground wire 10. neutral bonded to ground wire after service box 11. neutral not bonded to ground wire at service box 12. service box not grounded to ground wire 13. no ground in sub-panel 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 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 house 9. poor connections 10. illegal taps 11. neutral wire by-passes service box 12. fused neutral wire 13. fuses upstream of disconnect switch 14. obsolete box 15. exterior box not weather-tight 16. box not rated for aluminum

List 6 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

What caused the problem? List at least 3 things.

1. tends to creep out from under terminal screws 2. forms corrosion that is an electrical hazard 3. is softer than copper and easy to damage 4. some of the early material was of low quality and prone to breaking.

List 3 methods for securing wire ends.

1. terminal screws 2. push-in connectors 3. solderless connectors

What does the term "double tap" mean?

2 wires are connected to a single terminal.

Roughly 999 out of 1000 houses have _________ volts available.

240

How many wires would you typically find in a 240-volt service drop?

3

What would 4 wires mean?

3-phase electricity

What is the largest single-phase service that you are likely to find in a home?

400 amps

A fused 200-amp service has two 100-amp fuses in the service box. True or False?

False

All service entrance conductors must be attached above roof level. True or False?

False

All service entrance conductors must be in conduit. True or False?

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. True or False?

False

Load calculations are part of a home inspection.

False

One smoke detector is need in each home, near the kitchen because that's where most fires start. True or False?

False

The drip loop is typically part of the service drop. True or False?

False

The drip loop should be as close to the roof as possible. True or False?

False

The wire size for the service drop must be the same as the wire size for the service entrance conductors. True or False?

False

There can be up to 10 throws to disconnect all the electricity in the house. True or False?

False

Typical distribution panels have 60 circuits. True or False?

False

Wires run directly from the service box to the branch circuits. True or False

False

You are allowed to ground to the gas piping. True or False?

False

What is the advantage of a 240 volt circuit?

More electricity can flow at lower amp ratings

Does knob and tube wiring have a ground wire associated with it?

No

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 conditions. The ground wire should be reserved for emergency conditions.

Do we normally shut off the power when looking at the electrical system in the house? Why or why not?

No, it would be a significant inconvenience to the occupant.

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.

The grounding systems are connected to the house neutral at the ___________.

Service box

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.

How would you identify aluminum wiring?

The conductor is silver colored. The sheathing usually has the word ALUMINUM, ALUM, or AL.

What is meant by linking in multi-wire branch circuits.

The fuses or breakers for multi-wire branch circuits have to be shut off in pairs.

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.

From the point where the ground and neutral wires connect, there are 2 paths to ground. What are they?

Through the neutral service wire or through the grounding electrode conductor to water pipes or ground rods.

Aluminum is an acceptable service entrance conductor material. True or False?

True

The red and black wires of multi-wire circuits should be on separate bus bars. True or False?

True

The service box can be inside, outside, or in the garage. True or False?

True

The service size is determined by the amperage and the voltage ratings of the service.

True

Are service laterals overhead or underground?

Underground

What are the issues with running wire through steel studs?

Wires can be damaged by sharp edges on the steel studs. Wires passing through holes should be protected by grommets. Wires running parallel to studs should stand off the studs.

What are the implications of oversized breakers?

Wires can overheat without tripping the breakers.

Can an outlet be protected by a GFI without it being apparent?

Yes, all outlets downstream of a GFI will be protected.

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

Which of the following is a safety concern: a. a fuse that is too small. b. a fuse that is too big

a fuse that is too big

List clearances above ground, swimming pools, and roofs.

above roadway--18 ft. above driveway--12 ft. above flat roof--8 to 10 ft. above sloped roof--18 inches away from water in swimming pool--22.5 ft 3 ft. above sloped roof with pitch > 4 in 12 above walkway--10 ft.

Which of the following is a safety issue: a. The main fuses have a lower rating than the service entrance wire. b. The main fuses have a higher rating than the service entrance wire. c. The service box has a higher rating than the service entrance wires. d. The service box has the same rating as the service entrance wires. e. The distribution panel has a larger rating than the service entrance wires.

b

List 2 different branch wire materials you might see.

copper or aluminum

How should the feeder wires to a sub-panel from the main panel ideally be protected? a. No fusing is necessary. b. The main house breakers will protect the wire. c. Fuses should be provided at the subpanel. d. Fuses should be provided at the main panel. e. None of the above.

d.

Which of the following is a reliable way to identify the service size? a. the size of the service drop wires b. the distribution panel rating c. the service box rating d. the service entrance conductor e. the service entrance conduit size

d.

Implications of an undersized service include: a. shock hazard b. fire hazard c. shock and fire hazard d. melting insulation e. nuisance tripping of the main fuses and breakers

e.