Emergency vs. non-emergency

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Re: Emergency vs. non-emergency

I agree with Steve66 and Jim. This issue came up at our new NBA arena. I interpreted the code the same way Iwire did. I called NFPA and got their opinion. A single feeder from the generator is permitted to supply a switchboard or panelboard and then branch off to the different classes of loads. The emergency system does not begin until the feeder leaves this distribution point. From that point on it must be separate from normal power except at the transfer switch. As Jim said "Emergency source distribution" is the key here.
 
Re: Emergency vs. non-emergency

13-71 Log #3103 NEC-P13 Final Action: Accept
( 700.9(B) )
________________________________________________________________
Note: The Technical Correlating Committee has been advised by the Chairs of NFPA 99 and NFPA 110 that those committees agree with the panel action, but do not agree with the substantiation submitted. The Technical Correlating Committee agrees with those positions. The Technical Correlating Committee notes that CMP 15 stated the following
in the 1996 NEC ROP on the same issue: ?The feeders from the emergency generators to the first overcurrent device of any load, even nonessential ones, must be considered as part of the emergency system to protect system integrity.? The Technical Correlating Committee is directing that a Task Group consisting of members from CMP 13, NFPA 110 and NFPA 99 be formed to further discuss this issue for the 2008 NEC cycle.

Submitter: Kenneth E. Vannice, Leviton/NSI-Colortran / Rep. United States
Institute for Theatre Technology Engineering Comm.

Comment on Proposal No: 13-115

Recommendation: This proposal should continue to be rejected.

Substantiation: The emergency wiring must go clear back to the generator terminals. Non emergency wiring, where permitted, must also go clear back to the generator terminals. The old Panel 15 increased the size requirements of the generator terminal box to allow for this.

Panel Meeting Action: Accept

Number Eligible to Vote: 14

Ballot Results: Affirmative: 13 Negative: 1

Explanation of Negative:
WHITTALL: See my explanation of negative vote on Comment 13-6.
Comment on Affirmative:
WOOD: I agree with the panelʼs action on this comment. I disagree with the submitterʼs substantiation. It is not the panelʼs intent that emergency wiring go back to the generator terminals as it would prevent paralleling of generators or connecting non-emergency wiring to the generator system.
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Click to expand...
Can't wait to see what 2008 brings.
Jim
 
Re: Emergency vs. non-emergency

So does that support my interpretation (must go back to generator terminals) or rbb's phone call (go back to distribution panel)? :confused:
 
Re: Emergency vs. non-emergency

Well that all depends, were did the CMP draw the line "emergency source distribution"

It appears that if a distribution is a point were the wires "branch off" to distribute to several loads, a single feeder would be permitted. However, If the generators terminals or breaker is considered part of the distribution equipment, then two feeders from the generator would be required.

The CMP stated "The feeders from the emergency generators to the first overcurrent device of any load, even nonessential ones, must be considered as part of the emergency system to protect system integrity."
"It is not the panelʼs intent that emergency wiring go back to the generator terminals as it would prevent paralleling of generators or connecting non-emergency wiring to the generator system."

The handbooks comment states that "where an alternate power source supplies a switchboard from a single feeder or feeders in parallel, that switchboard may further distribute and provide power for the emergency, legally required, and optional standby systems. Switchboards provide the physical separation requirements of both system and wiring from a common power source. This physical separation cannot occur within a panelboard enclosure because of its open design. Individual overcurrent sections can supply emergency, legally required, and optional standby transfer switches."

The CMP and the NEC's Handbook seem to have conflicting opinions.

Like I said, I can't wait to see what 2008 brings.

Jim
 
Re: Emergency vs. non-emergency

I do not see very much conflict in the opinion of the CMP and that of the handbook.

The CMP talks about the line side of the first overcurrent device for each load.

The NEC handbook talks about a distribution switchboard constructed to provide load side separation.

The actual language in 700.9(B) says wiring must be independent after the "emergency source distribution overcurrent protection".

Isn't the main bussing of a switchboard on the line side of the first load overcurrent device?
 
Re: Emergency vs. non-emergency

Jim,

Isn't the main breaker on the generator the first emergency source distribution overcurrent protection device? Wouldn't the switchboard be on the load side of the first distribution breaker?

Or stated for the outcome of the decision, is there a requirement to bring 1 feed into the building from the emergency generator or do you need two?

Jim
(No really, I am not talking to myself) :)
 
Re: Emergency vs. non-emergency

Jim (yeah you not me),

I consider the breaker attached to the generator to be part of the generator. This breaker is sized/applied by the OEM to protect the generator not the load.

While supporting their ruling, the CMP said it is not their intent to prohibit the paralleling of generators at a point other than their winding terminals.
 
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