Unit 7: Electrical

Outlets should be close to basins. True or False?

True

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

True

Are service laterals overhead or underground?

underground

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

What would 2 wires usually mean?

120 volt service

The most common wire size for branch household circuits is ______ gauge.

14

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

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

1 1/4

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

List 3 common problems found with aluminum wiring.

1. connectors not compatible with aluminum 2. no anti-oxidant grease on stranded wires 3. overheating

The wire size for the service drop must be the same as the wire size for the service entrance conductors.

False

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

False

The drip loop is typically part of the service loop.

False

The drip loop should be as close to the roof surface as possible.

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.

False

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 circumstances. The ground wire should be reserved for emergency situations.

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

Service box

Which of the following is a reliable way to identify the service size? A. Size of the service drop wires B. Distribution panel rating C. Service box rating D. Service entrance conductor size E. Service entrance conduit size

Service entrance conductor size

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

Use a conventional circuit tester and operate the test button on the receptacle.

Do we normally shut off the power when looking at the 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.

What are the implications of oversized breakers?

Wires can overheat without tripping the breakers.

What are the issues on running wire through steel studs?

Wires may be damaged by sharp edges of steel studs. Wires passing through holes should be protected with grommets, for example. Wires running parallel to studs should stand off the studs.

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

Yes, all outlets downstream of a GFI outlet 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

Where is the anti-oxidant grease typically used?

on stranded aluminum wires

Is the service drop overhead or underground?

overhead

Abandoned wire should be ____________.

removed

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

service drop; service box

Distribution panels are also called _______

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

The grounding electrode conductor may also be called _________

the ground wire

Load calculations are part of a home inspection.

False

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

3

List 4 common problems found with switches.

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

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 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.

Give 4 examples of damaged wire.

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

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

List 3 methods for securing wire ends.

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

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

15 amp: 14 gauge 20 amp: 12 gauge 30 amp: 10 gauge 40 amp: 8 gauge

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

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

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

60 amp: 6 gauge 100 amp: 4 gauge 200 amp: 2-0 gauge

Which of the following is a safety concern? A. Fuse that is too small B. Fuse that is too big

A fuse that is too big

Why would heat lamps not be located over doors?

A towel thrown over the door may be ignited by a heat lamp.

What caused the problems?

Aluminum wire tends to creep out from under terminal screws. Aluminum wire forms corrosion (oxide) that is an electrical insulator. Aluminum wire is softer than copper and easier to damage when working with the wire. Aluminum wire was, in some of the early material, a low-quality wire prone to weakness & breaking.

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

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

False

List 5 common areas of water penetration into service entrances.

Conduit joints Mast head Roof flashing Meter base House entry

List 2 different branch wire materials you might see.

Copper Aluminum

List 13 common lighting problems found in houses.

Damaged or loose; Overheating; Inoperative; Obsolete; Not grounded; Missing; Poor stairway lighting; Conventional lights used in wet areas; Improper recessed light used in installations; Improper closet lighting; Heat lamps over doors; Isolating links needed on pull chains; Hanging light fixtures above a bathtub

List 13 common receptacle problems.

Damaged; Loose; Overheating; Ungrounded outlets; Open neutral or open hot connections; Reversed polarity outlets; Inoperative; Wrong-type receptacle; No GFIs; Worn receptacles; Broken pin or blade in slots; Not enough receptacles; Too far from basins

List 17 common branch circuit-wire problems.

Damaged; Wires run under carpets; Overhead wires not stranded; Not well secured; Loose connections; Open splices; Wires too close to ducts, pipes, vents, chimneys, and flues; Wires too close to the edge of studs or joists; Wires run through steel studs without protection; Exposed wires on walls or ceilings; Exposed wires in attics; Cable used outdoors; Buried cable not rated for buried use; Household wire used as extension; Undersized wire; Improper color coding; Abandoned wire

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

False

All junction boxes should be concealed. 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

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.

Fuses should be provided at the main panel

What are the two functions of earth grounding systems?

Help dissipate electricity from lightning Help avoid the buildup of static electricity

What is the difference between insulation & sheathing?

Insulation is around the individual wires Sheathing forms the cables by wrapping around the insulated wires

Wires should not be run on wall surfaces without ___________.

Mechanical protection

List 6 destinations where ground wires can terminate.

Metal water supply pipes Metal rods driven into the ground Wires buried in the footings of buildings (UFER ground) Buried grounding plates or rings The frames of metal buildings (not common in houses) Metal well casings

What is the advantage of a 240-volt circuit?

More electricity can flow at lower amp ratings

List 4 common problems found only with breakers.

Multi-wire circuits not linked Too many breakers Wrong breaker in panel Loose breakers

List 11 common problems with service entrance conductors.

No drip loop No mast head Masthead not weathertight Service entrance wires too close to roof Mast or conduit bent Mast or conduit rusted Mast rotted (if wood) Mast conduit or cable not well secured Mast conduit or cable not weathertight Conduit or cable not well sealed at house/wall penetration Cable frayed, damaged, or covered by siding

List 13 common problems found with grounding systems.

No grounding; Ground wire attach to plastic pipe; Ground wire after meters & valves with no jumper; Spliced ground wire; Poor connection; Ground connections not accessible; Ground rod cut off; Corroded ground rod; Undersized ground wire; Neutral bonded to ground wire after service box; Neutral wires not bonded to ground wire at service box; Service box not bonded to ground wire; No ground in sub panel feeder wires

Implications of an undersized service include which of the following? A. Shock hazard B. Fire hazard C. Shock & fire hazard D. Melting insulation E. Nuisance tripping of the main fuses or breakers

Nuisance tripping of the main fuses or breakers

List 16 conditions that may be found in all panels.

Obsolete and/or fused neutrals; Damaged panel or components; Loose or missing door; Openings in panel; Panel too small; Overheating; Rust or water in panel; Loose panel; Inappropriate support material; Circuits not labeled; Panel crowded; Poor access; Upside down; Not suitable for aluminum wiring; Poor location; Exterior panel not weather-tight

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.

List 9 common problems with service drops.

Overhead wires too low Overhead wires too high Damaged or frayed wires Trees or vines interfering with wires Wires too close to doors or windows Wires not well secured to the house Poor connection between service drop & service entrance Inadequate clearance from roofs Service lateral problems

List 17 common conditions you might find in a service box.

Poor access or location; Loose; Rust or water in box; Unprotected opening; Inappropriate support material; Damaged parts; Overheating; Incorrect fuse or breaker size; box rating too small; Service entrance wires exposed in house; Poor connections; Illegal taps; Neutral wire bypasses service box; Fused neutral wire; Fuses upstream of disconnect switch; Obsolete box; Exterior box not weather-tight; Box not rated for aluminum

Describe how knob and tube wiring is visibly different from modern cable.

The black & white wires are separate, so the circuit wires usually run in pairs. There are ceramic tubes protecting the wires where they pass through joists or studs. There are ceramic knobs where the wires change direction.

Explain the problem with reversed 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.

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 that the service entrance wire. C. The service box has a higher rating than the service entrance wire. 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.

The main fuses have a higher rating than the service entrance wire.

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 Through the grounding electrode conductor to water pipes or ground rods

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

True

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

True

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

True

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

True

List clearances above ground, swimming pools, and roofs.

above roadway: 18 feet above driveway: 12 feet above flat roof: 8-10 feet above sloped roof: 18 inches away from water in swimming pool: 22 1/2 feet in any direction 3 feet above sloped roof with pitch greater than 4 in 12 above walkway: 10 feet

When was it used?

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

How are lights tested?

turn them on and off by the switches