EETC Grounding Systems 5

Question 1

What happens to the neutral-to-ground bond in a subpanel (separate building panel)?

Accepted Answer

The neutral must be kept isolated from the grounding conductor

Answer

At a subpanel, the neutral (grounded conductor) must remain isolated from the equipment grounding conductor to prevent objectionable current on the EGC.

Question 2

Which type of ground fault protection is required on solidly grounded wye services of 150V to 600V to ground with service disconnects rated 1000A or more?

Accepted Answer

Ground fault protection of equipment (GFPE)

Answer

NEC 230.95 requires ground fault protection of equipment (GFPE) on solidly grounded wye services where the voltage exceeds 150V to ground and the disconnect is rated 1000A or more.

Question 3

A grounding electrode conductor splice, where permitted, must be made using which method?

Accepted Answer

Irreversible compression connectors or exothermic welding

Answer

NEC 250.64(C) permits splicing of grounding electrode conductors only by irreversible compression-type connectors or by exothermic welding.

Question 4

What is 'step potential' and why is it dangerous?

Accepted Answer

The voltage gradient across the earth's surface that can drive current through a person's legs during a fault

Answer

Step potential is the voltage difference between two points on the earth's surface separated by one stride, which can cause current to flow through a person's legs during a ground fault.

Question 5

When a metal water pipe is used as a grounding electrode, interior metal water piping beyond 5 feet from the building entrance must be:

Accepted Answer

Bonded to the grounding electrode system

Answer

NEC 250.104(A) requires that interior metal water piping beyond the 5-foot point of entry be bonded to the service equipment enclosure, grounded conductor, or grounding electrode conductor.

(EETC) Electrical Technician Certification Practice Test

(EETC) Electrical Technician Certification Practice Test

EETC Grounding Systems 5