Electrical Systems

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

True

Outlets should be close to basins. True False

True

Service entrance conductors run from the service drop to the service box or service panel.

True

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

True

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

True

What size 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

What would two wires usually mean?

120 Volt Service

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

14

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.

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

False

Is the service drop overhead or underground?

Overhead

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

False

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

False

The drip loop is typically part of the service drop.

False

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

False

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

False

Undersized service is dangerous

False, it's just a nuisance, breakers tripping a lot

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

No

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

Service box

Distribution panels are also called

Service panels, panelboards, auxiliary panels, sub panels, fuse boxes, fuse panels, breaker panels

What are the implications of oversized breakers?

Will allow wires to overheat without tripping

Can an outlet be protected by a ground fault interrupter without it being apparent?

Yes, all the downstream outlets will be protected

Wire should be ______ inches away from the edge of studs

one and a quarter inches

Roughly 999 out of 1,000 houses have ______ service entrance wires (insert a number)

3

What is meant by open splice?

. An open splice is a connection that is not made inside a junction box.

List three common problems found with aluminum wiring.

. Connectors not compatible with aluminum 2. No anti-oxidant grease on stranded wires 3. Overheating

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.

Describe how you would test a GFI receptacle during an inspection

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

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; b) 12 gauge; c) 10 gauge; d) 8 gauge

List two functions of the drip loop.

1) prevents water from going in the service mast, 2) shows the service wires are not straining the splices

When was aluminum wiring used?

1960's and 1970's

Roughly 999 out of 1,000 houses have ______ volts available (insert a number)

240

What is the largest sized service you may find in a home?

400 amp

Why should heat lamps not be located over doors?

A towel thrown over the door may be ignited

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

B

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

B

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

Because they are not visible, they may be stepped on.

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 size e. the service entrance conduit size

D

The functions of earth grounding systems include ______ .

Dissipate lightning and static

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

False

All junction boxes should be concealed. True False

False

The service entrance conductors run from the ______ to the ______

From service drop to the service box

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

Linking means that the fuses or breakers for multi-wire branch circuits have to be shut off in pairs.

What is the advantage of a 240-volt circuit?

More voltage can flow at a lower amp rating

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.

Are service laterals overhead or underground

Underground

What is the implication of a panel that is too small for the service

The panel may overheat.

Explain why fused neutrals are a bad idea

These are dangerous because the fuse on the neutral side only blows. The circuit may not work, but there may be voltage throughout the entire circuit.

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

Three

What would four wires mean?

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.

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

True

What does the term "double tap" mean?

Two wires connected to the same terminal

List clearances above ground, swimming pools, and roofs

above roadway—18 ft ■ above driveway—12 ft ■ above flat roof—8-10 ft ■ above sloped roof—18 inches ■ away from water in swimming pool—22½ ft in any direction ■ 3 feet above sloped roof with pitch greater than 4 in 12 ■ above walkway—10 f