E2 Emergency and Standby Systems 2

Question 1

Under NEC Article 700, how soon must an emergency system automatically restore power after normal supply fails?

Accepted Answer

Within 10 seconds

Answer

NEC 700.12 requires emergency systems to supply power within 10 seconds of normal power failure.

Question 2

Which NEC article governs Legally Required Standby Systems in commercial occupancies?

Accepted Answer

Article 701

Answer

NEC Article 701 covers Legally Required Standby Systems, which differ from emergency systems covered in Article 700.

Question 3

An automatic transfer switch (ATS) for an emergency system must be listed and be capable of withstanding:

Accepted Answer

Available fault current at the point of installation

Answer

Per NEC 700.5(A), transfer switches must be suitable for the available fault current at the point where they are installed.

Question 4

Emergency system branch circuits must be kept entirely independent of other wiring with a limited exception for:

Accepted Answer

Transfer equipment and exit lighting enclosures listed for the purpose

Answer

NEC 700.10(B) permits emergency wiring to share enclosures only at transfer equipment and exit lighting fixtures listed for the purpose.

Question 5

A generator used as the alternate power source for an emergency system must be provided with selective coordination from the emergency panel to the transfer switch for fault currents lasting:

Accepted Answer

0.1 second and longer

Answer

NEC 700.32 requires selective coordination of overcurrent devices for fault durations of 0.1 second and longer.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

E2 Emergency and Standby Systems 2