E-Lighting
- Thread starter Mark Jett
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- Location
- Massachusetts
If a single generator is backing up the entire building through a single transfer switch the NEC would not classify that as an emergency system and you would still need battery units.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Let’s get things in order. An “emergency load” becomes an “emergency load” only when a governmental agency says, “I want that load to be treated as an emergency load.” I believe that it is the building codes (as adopted by state and local governments) that state that the egress path from certain buildings shall be illuminated, in the event that the utility power is lost. The building codes go on to say that that egress lighting shall be treated as an “emergency load.” That is what brings the NEC article 700 into play.
Once you have a load, such as egress lights, designated as “emergency,” then the rules for providing power, and for separating the wiring, also come into play. Part of the article 700 rules include the statement that if the generator does not have enough capacity for 100 % of the building’s connected load, then you need some method of assuring that the available power is made available to the emergency loads, the legally required standby loads, and the optional standby loads, in that order of priority.
So to (finally) answer your question, if your generator has enough capacity for the entire building (a standard design feature for casinos), you still have to make sure that the wiring methods required by article 700 are met. You need to state which lights are for emergency egress, and you have to make sure (as an example) that the wiring to those lights is separated from the wiring to non-emergency loads. You also have to provide for selective coordination of the breakers that supply the egress lights and the breakers upstream.
Welcome to the forum.
Once you have a load, such as egress lights, designated as “emergency,” then the rules for providing power, and for separating the wiring, also come into play. Part of the article 700 rules include the statement that if the generator does not have enough capacity for 100 % of the building’s connected load, then you need some method of assuring that the available power is made available to the emergency loads, the legally required standby loads, and the optional standby loads, in that order of priority.
So to (finally) answer your question, if your generator has enough capacity for the entire building (a standard design feature for casinos), you still have to make sure that the wiring methods required by article 700 are met. You need to state which lights are for emergency egress, and you have to make sure (as an example) that the wiring to those lights is separated from the wiring to non-emergency loads. You also have to provide for selective coordination of the breakers that supply the egress lights and the breakers upstream.
Welcome to the forum.
- Location
- Illinois
- Occupation
- retired electrician
And if you comply with everything in Charlie's post, you still may have an issue with the 10 second rule in 700.12 if the generator is very large.
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