Required Generator Size??

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mcpritt

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Other than being common sense, are there any rules or regulations requiring what size a generator must be? For example, I have seen contractors installing a 8 kW portable genset to run a whole house, is this legal? Is any load shedding required? Their contention is the generator is protected from overload, so worse case the generator will just trip out.

What are your thoughts on this and are there laws against it??

Thanks,
Charlie
 
Re: Required Generator Size??

No NEC rules apply. You are talking about "Optional Standby" systems. 702 lets the owner decide how much load is intended to be served by the generator. The only requirement related to size (rating) is that the generator be capable of handling whatever load is intended to be connected to it.
 
Re: Required Generator Size??

Sounds like you are asking after Optional Standby Generators.

We were just kicking that one around over here a few days back.
 
Re: Required Generator Size??

We require a load calculation to be submitted with the permit application indicating all loads that will automatically be connected to generator on standby. If this load exceeds the rating of the generator, it will not be approved.

Therefore, the only options are to either install a manual transfer switch that permits the user to select the loads to be served each time the standby system is used, or use an automatic transfer switch that will only connect loads not exceeding the rating of the generator.
 
Re: Required Generator Size??

Thanks for the reply. I just missed the other post. I did read the posts and I get the impression that it is actually up to the AHJ.

Although it is not a good design, I do not think that Art 702.5 actually prohibits a whole house being connected to a small generator. Unless you actually "Intend" to power up everything.

Looks like the code should be revised so everyone will be held to the same standards. I agree that calculations should be made and a properly selected generator be used.

Thanks,
Charlie
 
Re: Required Generator Size??

Posted by mcpritt:
I get the impression that it is actually up to the AHJ.
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Unless the AHJ is backed up by ordinance or the Code, the AHJ will be running the risk of making his/er own code.

I find it real interesting the 702.5 says "User". Not owner, builder, electrician, contractor, AHJ, PoCo, manager, agent or anything else.

Is this anarchy? :D
 
Re: Required Generator Size??

Originally posted by al hildenbrand:
I find it real interesting the 702.5 says "User". Not owner, builder, electrician, contractor, AHJ, PoCo, manager, agent or anything else. . . . Is this anarchy?
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No, this is capitalism. ;) The "owner" gets to decide who the "user" will be, and it will probably be the "owner."
 
Re: Required Generator Size??

why would anyone but the end user (or maybe the owner) care what equipment is powered by an optional standby generator?

there is no reason whatsoever for the ahj to get involved in determining any calculations on this at all. if the load is too high for the generator, something will trip. it hurts nothing.
 
Re: Required Generator Size??

Originally posted by petersonra:
there is no reason whatsoever for the ahj to get involved in determining any calculations on this at all. if the load is too high for the generator, something will trip. it hurts nothing.
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We sure agree there.

I thought 702.5 makes that very clear no load calcs could be required by the AHJ.
 
Re: Required Generator Size??

Originally posted by charlie b:
Originally posted by al hildenbrand:
I find it real interesting the 702.5 says "User". Not owner, builder, electrician, contractor, AHJ, PoCo, manager, agent or anything else. . . . Is this anarchy?
Click to expand...
No, this is capitalism. :D
Click to expand...
 
Re: Required Generator Size??

Posted by Charlie B
The "owner" gets to decide who the "user" will be, and it will probably be the "owner."
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There are an awful lot of tenants out there who would not agree with the tenet of your supposition.
 
Re: Required Generator Size??

Have you met a lot of landlords (or landladies) who would provide a generator for the use of the tenants? I might try asking my landlord, but he would likely laugh and say, "Sure, right after I get one installed in my own house." :D
 
Re: Required Generator Size??

It happens in commercial space.

Sometimes a standby unit is included, in my experience generally after a tenant installs one and then later moves out. From that point on it is part of the owners sales pitch for leasing that space.

[ October 11, 2005, 05:44 PM: Message edited by: iwire ]
 
Re: Required Generator Size??

Originally posted by petersonra:
why would anyone but the end user (or maybe the owner) care what equipment is powered by an optional standby generator?

there is no reason whatsoever for the ahj to get involved in determining any calculations on this at all. if the load is too high for the generator, something will trip. it hurts nothing.
Click to expand...
Until it trips too many times and the little c/b's on the geneset are bypassed.
Isn't that the same reason we got rid of edison base fuses :confused:
 
Re: Required Generator Size??

Larry what does 702.5 say? :)

IMO the CMP went out of the way to keep the AHJs out of this particular issue. :D

[ October 11, 2005, 08:00 PM: Message edited by: iwire ]
 
Re: Required Generator Size??

this came up on another forum and I and most of the others on that site completely agree with Iwire, not surprisingly ( :cool: ), and it was the concensus that even very small generators can be hooked up.

However, it is probably cheaper to install a bigger generator than to try and fight a well run jurisdiction. If it is written into the amendments, forget it. It would be a winnable battle if only a policy, or sporadically enforced by the jurisdiction, but it still might be cheaper all around.

paul
 
Re: Required Generator Size??

The other day I over heard a conversation in the big O between a sales person and a potential buyer of a 15 kw genset and he told this poor guy that this genset would run his entire home a/c stove,oven etc....... and could be the nice guy and ask his neighbor if we wanted to plug in :eek:
But my tounge and walked away. :eek:
 
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