S95 Components and Power 2

Question 1

What is the minimum secondary (standby) power duration required for a fire alarm system connected to a supervising station?

Accepted Answer

24 hours standby plus 5 minutes alarm

Answer

NFPA 72 requires fire alarm systems monitored by a supervising station to operate for 24 hours on secondary power, then supply at least 5 minutes of full alarm operation.

Question 2

Which battery chemistry is most commonly used as the secondary power source in fire alarm control panels?

Accepted Answer

Sealed lead-acid (SLA)

Answer

Sealed lead-acid batteries are the industry standard for fire alarm panel backup due to their reliability, maintenance-free design, and proven service life.

Question 3

How must a fire alarm system respond when primary AC power is lost?

Accepted Answer

Transfer to secondary power immediately and automatically with no interruption

Answer

Per NFPA 72, the transfer from primary to secondary power must be automatic and immediate, with no gap in system operation.

Question 4

What AC input voltage variation must a listed fire alarm system power supply withstand without operational impairment?

Accepted Answer

±15%

Answer

NFPA 72 requires fire alarm power supplies to operate correctly across a ±15% variation in nominal AC voltage to accommodate normal utility fluctuations.

Question 5

When a fire alarm control panel displays a 'power trouble' indication, what is the FIRST supervisory action?

Accepted Answer

Verify that primary AC power is present at the panel

Answer

Confirming whether AC power is present at the panel is the first step, as a missing primary feed is the most common and simplest cause of a power trouble signal.

(S95) Supervision of Fire Alarm System Practice Test

(S95) Supervision of Fire Alarm System Practice Test

S95 Components and Power 2