Residential Emergency Generators

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gpwilson62

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Unfortunately I do not have a copy of 2011 NEC in front of me. Does 2011 NEC address the issue of backfeeding onto commercial lines from emergency generators in residential applications. Does it require either a manual or automatic xfer switch, or a way to disconnect SEC to prevent backfeeding and causing a safety hazard for linemen. if so what is the appropriate code reference. The 2005 NEC which I do have copy of allows exception for these 702.6 (ex) and I am trying to find out whether this has changed to require safety protection preventing backfeeding in the 2008 or 2011. Thanks
 
Although 702.5 allows it, there is no way I would do this for a customer and walk away assuming they would follow through on the "how to" instructions.
 
gpwilson62 said:
Unfortunately I do not have a copy of 2011 NEC in front of me. Does 2011 NEC address the issue of backfeeding onto commercial lines from emergency generators in residential applications. Does it require either a manual or automatic xfer switch, or a way to disconnect SEC to prevent backfeeding and causing a safety hazard for linemen. if so what is the appropriate code reference. The 2005 NEC which I do have copy of allows exception for these 702.6 (ex) and I am trying to find out whether this has changed to require safety protection preventing backfeeding in the 2008 or 2011. Thanks
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702.6 exception does allow it but I cannot think that any inspector would ever allow it or any EC would ever hook it up like that. A qualified person may live there now but who says that person will still be there next time the power goes out?
The more I read that exception the more amazed I am that it even got in the NEC.
 
gpwilson62 said:
The 2005 NEC which I do have copy of allows exception for these 702.6 (ex). . . .
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This article was not changed in 2008. I don't have the 2011 handy. Please note that the exception would not apply in most residential applications.
 
qcroanoke said:
A qualified person may live there now but who says that person will still be there next time the power goes out?
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The exception calls for conditions of maintenance and supervision that assure that only a qualified person services the installation. Having a qualified person as the homeowner does not give you those conditions. Perhaps a managed apartment or condo building could meet those conditions, but such buildings are not likely to employ temporary generators. That is why I said this exception would not apply to most residential buildings.
 
charlie b said:
This article was not changed in 2008. I don't have the 2011 handy. Please note that the exception would not apply in most residential applications.
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True. But wouldn't defining "where conditions of maintainance and supervision ensure that only qualified persons service the installation" be about as open to interpertation as defining "in a neat and workman like manner"?
Just saying......
Charlie you type a LOT quicker than me! LOL
 
Time for a reality check.

The NEC, and your local community, are not the only 'authorities' here. The PoCo is party to this transaction.

If the equipment is capable in any way of being connected to their system, it has to meet their standards. The PoCo has legal standing to disconnect from the home completely, demand the installation of equipment acceptable to them, and even to assess fines.

Also relevant is: what happens when the PoCo feed resumes? Their genny is a lot bigger - guess whose genny gets reduced to a pile of molten slag when the two fight it out?

This is the entire reason for transfer switches - whether manual or automatic. Manual transfer switches are available for maybe $500. There's no excuse to not use one.
 
renosteinke said:
Time for a reality check.

Also relevant is: what happens when the PoCo feed resumes? Their genny is a lot bigger - guess whose genny gets reduced to a pile of molten slag when the two fight it out?
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Article 702.6 (Exception) - Temporary connection of a portable generator without transfer equipment shall be permitted where conditions of maintenance and supervision ensure that only qualified persons service the installation and where the normal supply is physically isolated by a lockable disconnecting means or by disconnection of the normal supply conductors.

So if that happened it wasn't a compliant install to begin with.
 
qcroanoke said:
So if that happened it wasn't a compliant install to begin with.
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Exactly.

We happen to take advantage of 702.6 exception often, either by opening a main and placing LOTO on it or in some cases lifting the (dead) service conductors off the bus and insulating them.

The power company is well aware of this because once the power failure is over we have to call the power company out to kill the service temporarily while we land the service conductors back onto the bus.
 
A point of clarification on your term Residential Emergency Generator. Article 700 covers emergency systems, 701 legally required standby systems and 702 is optionally required standby systems. Review the scope in the .1 section to see what they are. An emergency is painted red, is up to speed in ten seconds, uses a listed emergency transfer switch, and costs a lot of money.
Nearly all residential generators are article 702 applications so the homeowner can watch the superbowl when the power goes out. There may be a very few residential article 701 applications and I would be pretty confident is saying there are no residential 700 systems.
 
I think there was a thread posted right after hurricane Charlie, where three electricians went to prison for killing three line men, because of back feeding the utility when power was out, in no way would I ever install a generator without a transfer switch.
 
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