ABAT Power Systems & Backup Power for Alarm Systems 1 — Questions and Answers
Question 1: According to NFPA 72 and UL 681, what is the minimum standby battery backup time required for a residential burglar alarm control panel?
- 4 hours
- 8 hours
- 24 hours (Correct answer)
- 72 hours
Correct answer: 24 hours
NFPA 72 and UL 681 require a minimum of 24 hours of standby power followed by sufficient capacity to operate all alarms for a defined period.
Question 2: Which type of battery is most commonly used as the primary backup power source in residential and commercial burglar alarm control panels?
- Lithium-ion (Li-ion)
- Sealed lead-acid (SLA) (Correct answer)
- Nickel-cadmium (NiCd)
- Nickel-metal hydride (NiMH)
Correct answer: Sealed lead-acid (SLA)
Sealed lead-acid (SLA) batteries are the industry standard for alarm panel backup due to their low cost, maintenance-free design, and reliable discharge characteristics.
Question 3: What is the typical float charge voltage applied to a 12V sealed lead-acid alarm panel battery?
- 11.5–12.0 V
- 12.5–12.8 V
- 13.5–13.8 V (Correct answer)
- 14.4–14.8 V
Correct answer: 13.5–13.8 V
A 12V SLA battery is maintained at approximately 13.5–13.8 V during float charging to keep it fully charged without overcharging.
Question 4: When testing a standby battery in an alarm panel, a technician measures 11.2 V under load. What does this indicate?
- The battery is fully charged
- The battery is at 50% charge
- The battery is sulfated or failing and should be replaced (Correct answer)
- The charger is supplying too much voltage
Correct answer: The battery is sulfated or failing and should be replaced
A 12V SLA battery reading below 11.8 V under load indicates excessive discharge depth or sulfation, signaling imminent failure and need for replacement.
Question 5: An alarm panel's power supply draws 500 mA during normal operation and 1.5 A when all sirens are active. The backup battery is rated at 7 Ah. Approximately how long will the battery sustain the panel in alarm state only?
- About 1.5 hours
- About 4.7 hours (Correct answer)
- About 14 hours
- About 3.5 hours
Correct answer: About 4.7 hours
Dividing the 7 Ah capacity by the 1.5 A alarm draw gives approximately 4.7 hours (7 ÷ 1.5 = 4.67 hours).
Question 6: What does the UL listing require a burglar alarm power supply to do when AC power is lost?
- Immediately trigger a trouble signal at the keypad
- Automatically switch to battery backup without interruption to the protected zone circuits (Correct answer)
- Disconnect all peripheral devices to conserve battery
- Shut down the panel and log the event
Correct answer: Automatically switch to battery backup without interruption to the protected zone circuits
UL requires seamless, automatic transfer to battery backup to maintain continuous protection without interrupting zone monitoring or signaling.
Question 7: Which wire gauge is typically required for the 120 VAC connection to a hardwired residential alarm panel transformer to comply with NEC Article 725?
- 18 AWG
- 16 AWG
- 14 AWG (Correct answer)
- 12 AWG
Correct answer: 14 AWG
NEC Article 725 and standard electrical code require a minimum of 14 AWG for 120 VAC branch circuits serving alarm transformers, matching standard 15 A circuit requirements.
ABAT Power Systems & Backup Power for Alarm Systems 1
According to NFPA 72 and UL 681, what is the minimum standby battery backup time required for a residential burglar alarm control panel?