Generator and emergency lights-Commercial building

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Ragin Cajun

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Upstate S.C.
I am working on a bank operations center that will have the whole building (less electric zone strip heats to suppliment gas heat). 150KW generator so capacity is not an issue.

Building has lots of computers, each with it's own UPS for carry-over during the transfer time.

The generator will start within 10 seconds.

Can I omit the battery backed-up emergency and exit lights?

Do I have to have a dedicated transfer switch for "life safety," or is that requirement only for a hospital?


Thanks

RC
 
The phrase "life safety" only comes into play at a hospital (or other facility covered by 517).

So what you have to find out is whether this generator will come under the rules of 700 or 701 or 702. If you do choose to use this generator as the only source of power to the lights that will lead people to the exits, then you are in 700. If this generator only gives power to loads that allow the facility to continue to function, then you are in 702.
 
A "bit" more detail. Obviously, the "emergency lights" fall under 700. The rest of the loads fall under 702.

Does 700 imply that a separate transfer switch is needed for the emergency lights and another transfer switch for all other loads? If that's the case, it's cheaper to go with battery packs to avoid multiple transfer switches, dedicated panelboard, and isolated conduits running all over the building.
 
It was "suggested" that since the job had a large generator to use it for emergency lights and same all that $$$ from not using battery packs. I didn't think it was that simple and wanted to be sure I was right. Nothing like being put on the spot for a "quick answer."


Thanks for the confirmation.



RC
 
Emergency System

Emergency System

It is a misnomer to call a generator an "Emergency Generator". The generator is more appropriately designated as a stand-by source or stand-by generator. You will not have an Emergency System (700) until such time as you reach your transfer switch, everything after and including the xfr switch is now part of the emergency system and needs to comply with article 700.

If it is the desire of the owner/designer then you may also supply optional (702)or legally required (701) loads from the genset through a separate xfr switch. The 701 and 702 loads may share the same switch and distribution system. The 700 system must be entriely independant of any other wiring or system.

Up to the point where you have a specific system you may share equipment. As an example, you may run a feeder from the genset to a distribution board. The DB may then have separate breakers in it to feed the emergency and other systems.
 
That was well stated, mptashkin, a very good summary of the relationship between the source, the DP, and the transfer switches. Welcome to the Forum.
 
I have a situation similar to this. Would it be accptable to put some of the heating system and some pumps on the Art. 700 switch that the owner has requested not to be "shed" under certian conditions?
 
Probably not, see 700.15 and 700.18. Unless these items can be classified as necessary for life safety, they would have be supplied from a separate transfer switch.

Roger
 
Roger

I understand what you are saying, but am having a hard time convincing myself that the building heating system should not be on "life safety" system.

I have done projects in the past that fall into Art. 517 and I know for sure that heating is not to be on the life safety switch but this is a different situation.

I would appreciate any other advice that would clear this up and knock down the wall I am creating for myself.
 
Corey, in a hospital (517 application) there are areas that must have a conditioned or heated environment for patients, these would be supplied by the Critical or Equipment branches.

Article 517 is special that in small installations (150 KVA or less) the whole essential system (all three branches) can be supplied from one transfer switch even though there are equivalent 700, 701, and 702 type loads served.

Roger
 
Roger

Does 700.5(B) allow me to mix/match life safety and non-essential loads as long as my gen. set is sized for 100% of the load?
 
Corey, yes it does. 700.5(B), as you know is pertaing to the "power source", and if the "power source" can handle all the loads it can supply, one, two, or more transfer switches, this article section also allows for peak shaving if the "power source" can handle it.

The article section does not allow the "emergency" (article 700) transfer switch to supply these loads though.

Roger
 
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