Grady22
Hello to all- Va is currently using the 2008 NEC. As I read article 702.5 (2) (a), it says: The standby source shall be capable of supplying the full load that is transferred by the transfer equipment.

The above article (the 2 part of the article) is in regards to a system using a automatic transfer switch.

I take it to mean that, in effect, the homeowner will have to have larger generators to be able to run the load supplied to it at one time. I also realize that the homeowner can also use the sub-panels with up to 16 spaces to reduce the size of the generator.

Am I correct in my thinking?
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rico567
Grady22;10083 wrote:
Hello to all- Va is currently using the 2008 NEC. As I read article 702.5 (2) (a), it says: The standby source shall be capable of supplying the full load that is transferred by the transfer equipment.

The above article (the 2 part of the article) is in regards to a system using a automatic transfer switch.

I take it to mean that, in effect, the homeowner will have to have larger generators to be able to run the load supplied to it at one time. I also realize that the homeowner can also use the sub-panels with up to 16 spaces to reduce the size of the generator.

Am I correct in my thinking?


There was some discussion about that in another thread on this forum the other day......and an expert (not me) concluded that the NEC is more complex than that. It states in part (b) that if the load is managed, the generator only has to support the load that's transferred to it....which management may enable a far smaller amperage than the total possible load.
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ceb58
Grady22;10083 wrote:
Hello to all- Va is currently using the 2008 NEC. As I read article 702.5 (2) (a), it says: The standby source shall be capable of supplying the full load that is transferred by the transfer equipment.

The above article (the 2 part of the article) is in regards to a system using a automatic transfer switch.

I take it to mean that, in effect, the homeowner will have to have larger generators to be able to run the load supplied to it at one time. I also realize that the homeowner can also use the sub-panels with up to 16 spaces to reduce the size of the generator.

Am I correct in my thinking?


You are correct in your thinking except for the 16 space panel. You can have as many spaces as you want as long as the calculated load meets the requirements.
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Skip Douglas SkipD
ceb58;10085 wrote:
You are correct in your thinking except for the 16 space panel. You can have as many spaces as you want as long as the calculated load meets the requirements.
Additional - even if the generator powered only a 16-breaker panel and the 16 breakers were tied to loads that, when totaled, exceed the capacity of the generator (and there was no automated load management employed), you would be in violation of the NEC 2008 (and probably 2011 but I don't have a copy of it yet).
Skip Douglas
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genme
The newer nexus air-cooled generators have overload protection built in to them (I have no idea about older generators.) Would overload protection, where the generator shuts down if overloaded, be considered a managed system, or does managed mean the generator must continue to run (if so, why)?
Model 5875, Nexus controller, 999cc Engine, 20kW LP, 2011
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Skip Douglas SkipD
genme;10098 wrote:
The newer nexus air-cooled generators have overload protection built in to them (I have no idea about older generators.) Would overload protection, where the generator shuts down if overloaded, be considered a managed system, or does managed mean the generator must continue to run (if so, why)?
I'm not sure of the code issues, but the way I read the NEC 2008 the breaker on the generator has nothing to do with the load calculation issues. In my case, the generator is rated for 66.6A and has an 80A breaker. The breaker is only there to protect the wire between the generator and the transfer switch (and maybe a bit beyond that).

In addition, I would not want to load a generator to 100% of its capacity and then some as the voltage would probably drop and some of the powered equipment may not like that. I want some headroom with my generator's capability.
Skip Douglas
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genme
Thanks Skip. When I said overload protection, I was actually thinking of "under-frequency" and "under-voltage" protection shutdowns. I agree that getting to this point would be undesirable.
Model 5875, Nexus controller, 999cc Engine, 20kW LP, 2011
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ceb58
genme;10098 wrote:
The newer nexus air-cooled generators have overload protection built in to them (I have no idea about older generators.) Would overload protection, where the generator shuts down if overloaded, be considered a managed system, or does managed mean the generator must continue to run (if so, why)?


Overload protection is just that, protection. It protects the equipment from short circuits and ground fault conditions. It has nothing to do with load management.

702.5 was a code change for the 2008 NEC, and remains in the 2011, for several reasons. By the 05 code I could sell some one a 10Kw generator for a whole house generator setup. But the home may calculate at say 180 amp. Then the power goes out, gen. starts, transfers and over loads shutting down the generator. So there you are sitting in the dark not having a clue as what to do. Now what if the people were retired and elderly stumbling around trying to get the generator going. Not a good situation. It could be seen as a life safety issue.
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hoghead
I would check on when your county is changing over to the 08. The counties I work in are not switching until sometime next year.
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