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Emergency Circuit Questions NEC 700 #179618 07/24/08 07:07 AM
Joined: Jul 2004
Posts: 136
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cgw Offline OP
Member
building with a generator which has separate emergency transfer switch/panelbd and standby transfer switch/panelboard.
Can the fire alarm system be connected to the emergency system or would it be considered legally required standby power?

A branch circuits for emergency lighting need to run a good distance down a hall which does not have a fire sprinkler system. 700.9(D)(1), assuming it applies to my building, does it apply to branch circuits? If so does anyone manufacture a 1 hour cable or protective system?

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Re: Emergency Circuit Questions NEC 700 [Re: cgw] #179619 07/24/08 08:26 AM
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renosteinke Offline
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Connect the fire alarm wherever you like ... if it's a UL listed control panel / alarm system, it is already required to have, as part of the system, a 24 hr. back-up power supply (ie: big battery).

Re: Emergency Circuit Questions NEC 700 [Re: cgw] #179620 07/24/08 08:58 AM
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earlydean Offline
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Fire Alarm Systems as covered in NFPA 72 require a secondary power supply, not an "emergency source", nor is it classed as a "legally required standby source". Fire alarm secondary power is usually accomplished via batteries. Check out Chapter 4 of NFPA 72.

Only those loads required to be emergency loads are allowed to be connected to emergency sources. (NEC 700.9(B))

So, no, you cannot use an existing emergency source for the fire alarm system.

However, there is not a prohibition for loads cannected to the "legally required standby source".

But, NFPA 72, in section 4.4.1.9.3.1 requires engine-driven generators to comply with NFPA 110, for a Type 10, Class 24, Level 1 System. Type 10 means the generator starts and transfers within 10 seconds. Class 24 means there is enough fuel to operate at full load for 24 hours. Level 1 systems shall be installed when failure of the equipment to perform could result in loss of human life or serious injuries.

And, NFPA 72 section 4.4.1.5.1 requires a four hour battery system if a prime mover provides the power for continuity of service.

So, the bottom line: Use batteries, forget the generator.


Earl
Re: Emergency Circuit Questions NEC 700 [Re: earlydean] #179624 07/24/08 01:01 PM
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cgw Offline OP
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Thanks for the heads up.
We will have battery backup and it looks like the power will be on the standby system vs. the emergency system.

Re: Emergency Circuit Questions NEC 700 [Re: cgw] #179632 07/24/08 09:32 PM
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Posts: 136
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cgw Offline OP
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I still have the lighting circuits to run down the un-sprinklered hallway. Does anyone manufacture a 1 hour cable or protective system?


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