Separate systems
- Thread starter bobw
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Re: Separate systems
Bob,
The Short Answer Is No.
Since The 277V Circuit Is Also An Emergency Circuit 1999 NEC 700-9(b) Says That You Cannot Do What You Are Stating.
If The 277V Circuit Was Another Normal Poer Circuit Then The Answer Would Have Been Yes It Is Acceptable.
-Ed
Bob,
The Short Answer Is No.
Since The 277V Circuit Is Also An Emergency Circuit 1999 NEC 700-9(b) Says That You Cannot Do What You Are Stating.
If The 277V Circuit Was Another Normal Poer Circuit Then The Answer Would Have Been Yes It Is Acceptable.
-Ed
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Separate systems
And here's the longer answer:
Let?s start by backing up one half step, and being a bit more precise in our choice of words. Ed?s answer would be correct, if Bob?s question made correct and proper use of the phrase ?emergency generator.? But I have heard the word ?emergency? used many times, and each time improperly, when the equipment was not subject to the rules of article 700.
A facility might have a generator on-site, and that generator might be capable of automatically starting and taking on load when the utility feed is lost. But that does not make it an EMERGENCY generator. The phrase ?emergency generator? should only be used when, as article 700 says, the system is ?intended to supply, distribute, and control power and illumination essential for SAFETY TO HUMAN LIFE? (my emphasis).
If a store owner wants to have a generator on-hand so the cash registers can still operate, then we are not talking about emergency equipment. There are also ?Legally Required Standby? systems (Article 701) and ?Optional Standby? systems (Article 702). Neither of these two articles prohibit the configuration that Bob has described.
So back to you, Bob: Are you truly dealing with an ?emergency system,? or is this a ?standby? system?
And here's the longer answer:
Let?s start by backing up one half step, and being a bit more precise in our choice of words. Ed?s answer would be correct, if Bob?s question made correct and proper use of the phrase ?emergency generator.? But I have heard the word ?emergency? used many times, and each time improperly, when the equipment was not subject to the rules of article 700.
A facility might have a generator on-site, and that generator might be capable of automatically starting and taking on load when the utility feed is lost. But that does not make it an EMERGENCY generator. The phrase ?emergency generator? should only be used when, as article 700 says, the system is ?intended to supply, distribute, and control power and illumination essential for SAFETY TO HUMAN LIFE? (my emphasis).
If a store owner wants to have a generator on-hand so the cash registers can still operate, then we are not talking about emergency equipment. There are also ?Legally Required Standby? systems (Article 701) and ?Optional Standby? systems (Article 702). Neither of these two articles prohibit the configuration that Bob has described.
So back to you, Bob: Are you truly dealing with an ?emergency system,? or is this a ?standby? system?
- Location
- Illinois
- Occupation
- retired electrician
Re: Separate systems
Just remember that if this is not an emergency system, the circuits are in a common raceway, and the circuits are multiwire that 210.4(D) requires that all of the ungrounded conductors be identified as to phase and voltage. Also 200.6(D) requires that the grounded conductor of one sytem be white or gray and that for the second system that it be white with a colored stripe.
Don
Just remember that if this is not an emergency system, the circuits are in a common raceway, and the circuits are multiwire that 210.4(D) requires that all of the ungrounded conductors be identified as to phase and voltage. Also 200.6(D) requires that the grounded conductor of one sytem be white or gray and that for the second system that it be white with a colored stripe.
Don
- Location
- Massachusetts
Re: Separate systems
In the area I work the inspectors are all over this.
If the generator runs the egress lighting it is an Article 700 emergency generator.
Almost all other loads would be considered Article 702 Standby.
In the area I work the inspectors are all over this.
If the generator runs the egress lighting it is an Article 700 emergency generator.
Almost all other loads would be considered Article 702 Standby.
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