Wiring & Installation Techniques Flashcards

When installing EMT conduit, the maximum support spacing for conduit sized 3/4 inch and smaller is:

Answer: 10 feet

NEC 358.30 requires EMT 3/4 inch and smaller to be supported within 3 feet of each box and at intervals not exceeding 10 feet.

Which type of cable is specifically designed for direct burial without conduit?

Answer: UF-B

UF-B (Underground Feeder) cable is rated for direct burial applications without requiring conduit.

When pulling wire through conduit, the maximum fill percentage for three or more conductors is:

Answer: 31%

NEC Chapter 9 Table 1 limits conduit fill to 31% of interior cross-sectional area when three or more conductors are installed.

A 20-amp, 120-volt bathroom receptacle circuit must be:

Answer: GFCI protected only

NEC 210.8 requires all bathroom receptacles to have GFCI protection due to proximity to water sources.

The minimum burial depth for PVC conduit (Schedule 40) under a residential driveway is:

Answer: 18 inches

NEC Table 300.5 requires PVC conduit under driveways to be buried at least 18 inches deep.

When installing a service entrance, the weatherhead must be positioned so that:

Answer: Conductors enter from the bottom facing down

Conductors must enter the weatherhead from below with drip loops to prevent water from following the wires into the conduit.

What is the purpose of using anti-oxidant compound when terminating aluminum conductors?

Answer: To prevent corrosion and reduce resistance at connections

Anti-oxidant compound prevents aluminum oxidation at connections, which would increase resistance and create a fire hazard.