CITB CITB Electrical and Mechanical Services

Question 1

What minimum distance must be maintained when working near overhead power lines on a US construction site?

Accepted Answer

10 feet

Answer

OSHA requires a minimum clearance of 10 feet from overhead power lines up to 50 kV.

Question 2

Which document governs electrical installations in US construction buildings?

Accepted Answer

NFPA 70 (NEC)

Answer

NFPA 70, the National Electrical Code (NEC), sets the standard for safe electrical installations in US buildings.

Question 3

What color is the grounding (earth) wire in a standard US three-wire electrical circuit?

Accepted Answer

Green or bare copper

Answer

In US wiring, the grounding conductor is identified by green insulation or bare copper.

Question 4

What is a Ground Fault Circuit Interrupter (GFCI) used for on construction sites?

Accepted Answer

Protecting against electrocution from ground faults

Answer

GFCIs detect small ground fault currents and quickly cut power to prevent electrocution.

Question 5

Which pipe material is commonly used for domestic cold-water supply in US residential construction today?

Accepted Answer

PEX

Answer

PEX (cross-linked polyethylene) is the dominant choice for domestic cold-water supply due to flexibility and corrosion resistance.

(CITB) Construction Industry Training Board Practice Test