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