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Temporary Generator #78336
09/10/01 03:35 PM
09/10/01 03:35 PM
Joe Tedesco  Offline OP
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
305-6(a), Exception No.1. What is the reasoning
for this exception? I know it's been in there for years. How can you tell if
you meet this exception? I know the obvious if its over 5 kw but say you got
a 4500 watt generator (which are common), how do you know if you meet this?
I was told one way if you have dual voltage 120/240 then you would not meet
that exception. Is that dual voltage reasoning (if true at all) because if
you had 240, you would have 2 hot wires and one neutral thus equal 3 wires?


[This message has been edited by Joe Tedesco (edited 09-10-2001).]


Joe Tedesco, NEC Consultant
2017 / 2014 NEC & Related Books and Study Guides
Re: Temporary Generator #78337
09/10/01 06:09 PM
09/10/01 06:09 PM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
Joe,
Even if it is only a 2 wire generator, you can't use the exception. 250-20(b) requires the system to be a grounded system. There is nothing in 305 that says it doesn't have to be a grounded system and if it is grounded, then GFCI protection is required. If its not grounded, it is a violation of 250-20(b).
Don(resqcapt19)


Don(resqcapt19)
Re: Temporary Generator #78338
09/10/01 06:14 PM
09/10/01 06:14 PM
S
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,342
Joe, i think they mean the 120V receptacles on the 5kw and less units, regardless of other features.
I'll bet this exception was lobbied by the makers of generators.

Re: Temporary Generator #78339
09/11/01 10:49 AM
09/11/01 10:49 AM
Joe Tedesco  Offline OP
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
Thanks for your replies. I expect that the person who asked this question will join in soon, I hope.

Joe


Joe Tedesco, NEC Consultant
Re: Temporary Generator #78340
09/11/01 09:11 PM
09/11/01 09:11 PM
B
buddy  Offline
Member
Joined: Sep 2001
Posts: 8
I posted the question to the board and don't really agree with the responses and here's why. I don't think the generator has to be grounded and if it was, then what requires GFCI protection? That is what the exception is all about, not requiring GFCI's. What I basically want to figure out is how is an inspector supposed to know if a generator meets that exception? Thanks

Re: Temporary Generator #78341
09/12/01 08:03 AM
09/12/01 08:03 AM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
Buddy,
In my opinion, this exception could be used if you verify that there is not a bond between the frame of the generator and a circuit conductor. The exception also requires that it only be a 2 wire generator, which would preclude the use of a 120/240 volt generator. Are there any portable generators currently available that do not have a conductor bonded to the frame? I've never seen one without this bond.

Is a portable generator a separately derived system?

Don(rsqcapt19)


Don(resqcapt19)

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