Emergency vs normal circuits.

[mbrooke]

In buildings where emergency lighting circuits exist fed via a legally required standby generator (option chosen over bug eyes), what governs the design of the emergency circuit?


So far Im being told that the emergency circuit must run horizontal to the normal circuit, must be in separate painted red conduit, Exit signs must be a different circuit, the emergency circuit can not be switched and a certain foot candle amount needs to be achieved, however Im confused as to what sections requires these.

 

[liquidtite]

sounds like more of a local code or certain specs for that particular job.

 

[mbrooke]

sounds like more of a local code or certain specs for that particular job.

I think so. Im not finding half of it in the NEC. Could be other NFPA documents.


But in terms of what is under NEC allowance, what sections should a consider?

 

[cadpoint]

I agree with Liquidtite! Article 701 states what's the minimum required!

All this other stuff is usually stated in the Spec's of a job and done by an engineer.
Ask for a copy of the spec and a copy of the drawings! :thumbsup:

 

[Pharon]

In buildings where emergency lighting circuits exist fed via a legally required standby generator (option chosen over bug eyes), what governs the design of the emergency circuit?

You need to be careful about this. Article 700 typically covers emergency egress lighting and exit signs -- basically stuff essential for safety to human life. The 2014 NEC Handbook has a good description of the difference between Emergency, Legally Required, and Optional Standby loads (in 701.1):

Legally required standby systems are intended to provide electric
power to aid in fire fighting, rescue operations, control of health
hazards, and similar operations. In comparison, emergency systems
(see Article 700) are those systems essential for safety to life.
Optional standby systems (see Article 702) are those in which failure
can cause physical discomfort, interruption of an industrial
process, damage to process equipment, or disruption of business,
for example.

Keep in mind that each branch will require its own dedicated automatic transfer switch. The Emergency ATS needs to transfer within 10 seconds. The Legally Required switch can take up to 60 seconds. All Emergency switchboards and panelboards will also require surge protection per 700.8.

So far Im being told that the emergency circuit must run horizontal to the normal circuit, must be in separate painted red conduit, Exit signs must be a different circuit, the emergency circuit can not be switched and a certain foot candle amount needs to be achieved, however Im confused as to what sections requires these.

See 700.10(B) for separation requirements. Foot-candle requirements can be found in NFPA 101, Section 7.9.2.1 (http://www.bigbeam.com/lsc_NFPA101.html).

 

[ASG]

Some of these items (painting, foot candles) may be in your AHJ's building codes or (as they are called in NYC) Local Laws.

 

[mbrooke]

You need to be careful about this. Article 700 typically covers emergency egress lighting and exit signs -- basically stuff essential for safety to human life. The 2014 NEC Handbook has a good description of the difference between Emergency, Legally Required, and Optional Standby loads (in 701.1):


Keep in mind that each branch will require its own dedicated automatic transfer switch. The Emergency ATS needs to transfer within 10 seconds. The Legally Required switch can take up to 60 seconds. All Emergency switchboards and panelboards will also require surge protection per 700.8.


See 700.10(B) for separation requirements. Foot-candle requirements can be found in NFPA 101, Section 7.9.2.1 (http://www.bigbeam.com/lsc_NFPA101.html).

I guess I need to determine what is life safety vs optional standby. This does feed egress lights, but is also feeding room lights as well (ie 8 trofers in a conference room, one in the center is emergency) so I guess these must be on a separate ATS?

 

[Pharon]

Yes, unfortunately if you're feeding egress lights and exit signs from that generator, you will need a dedicated ATS for those loads. It might be cheaper to just do battery packs for the egress lights and call it an optional standby generator.

 

[mbrooke]

Yes, unfortunately if you're feeding egress lights and exit signs from that generator, you will need a dedicated ATS for those loads. It might be cheaper to just do battery packs for the egress lights and call it an optional standby generator.

I could in theory feed all from the generator, but as long as my egress lights have a bodine for 2 hours I can call the generator optional?

 

[Pharon]

Yes, I would say you'd be correct on that.

 

[mbrooke]

Yes, I would say you'd be correct on that.

Got it. Probably will come out cheaper that way.