Emergency and Standby Systems Flashcards

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

Answer: Within 10 seconds

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

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

Answer: Article 701

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

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

Answer: Available fault current at the point of installation

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

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

Answer: Transfer equipment and exit lighting enclosures listed for the purpose

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

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:

Answer: 0.1 second and longer

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

Where must the location of emergency system components be indicated in a commercial building?

Answer: On a drawing posted at the main service location

NEC 700.10(A) requires a sign at the main service showing the type, capacity, and location of all on-site emergency power sources.

Emergency lighting circuits supplying exit signs must be capable of operating for a minimum of:

Answer: 90 minutes on battery backup

NFPA 101 and NEC 700 require emergency lighting to be capable of operating for a minimum of 90 minutes after loss of normal power.