# Emergency standby generator feeder branch circuit to another building



## Bbsound (Dec 16, 2011)

We may have done something like this, and the AHJ may not have approved it, so we might have added a disconnect outside next to the orginal service and labeled all as having 2 services to the building.


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## BBQ (Nov 16, 2010)

Nothing wrong with the plan at all.

A couple of points, don't call it an emergency generator, to the NEC that would be an optional standby generator. The reason this is important is that the rules are much tougher for emergency generators than optional standby generators. 

The fact it powers the entire building means it is optional not emergency. 

Beyond that disconnecting means are required where this feeder enters the second building as Bsound mentioned.


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## BBQ (Nov 16, 2010)

Bbsound said:


> We may have done something like this, and the AHJ may not have approved it, so we might have added a disconnect outside next to the orginal service and labeled all as having 2 services to the building.


Not exactly correct, the building would have two sources of power but only one service.


A service can only be provided by a utility. 




> *Service*. The conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served.


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## denny3992 (Jul 12, 2010)

Yup done the close to the same.... 30kw 120/240D feeding one building(fire hall/bar) and also te truck garage which was 120/240 single ph service... I put a disc on outside of buildings before entrance to provide disco means( lockable) as the gen had its own building in between


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## MEC (Sep 14, 2013)

I appreciate the feed back. The power source from the fire station would be entering the building at the same area as the service, with a disconnect and it would be labeled as an additional power source. I would have to also make certain that the raceways and cables to the circuits coming from this power source only contain the wiring from that power source. I would also have to label the raceways, cables and devices.


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## denny3992 (Jul 12, 2010)

MEC said:


> I appreciate the feed back. The power source from the fire station would be entering the building at the same area as the service, with a disconnect and it would be labeled as an additional power source. I would have to also make certain that the raceways and cables to the circuits coming from this power source only contain the wiring from that power source. I would also have to label the raceways, cables and devices.


I made all conduit and covers red and labeled em circuits...


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## BBQ (Nov 16, 2010)

MEC said:


> I would have to also make certain that the raceways and cables to the circuits coming from this power source only contain the wiring from that power source. .


Not required and I would not bother doing that. 



> I would also have to label the raceways, cables and devices


Nice but pretty much not required.


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## BBQ (Nov 16, 2010)

denny3992 said:


> I made all conduit and covers red and labeled em circuits...


Again it is unwise to call them emergency circuits if they are not NEC emergency circuits.


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## BBQ (Nov 16, 2010)

This may help

This is from article 700 emergency systems. 


Part of 700.1



> Emergency systems are those systems legally required and classed as emergency by municipal, state, federal, or other codes, or by any governmental agency having juris-diction. These systems are intended to automatically supply illumination, power, or both, to designated areas and equip-ment in the event of failure of the normal supply or in the event of accident to elements of a system intended to sup-ply, distribute, and control power and illumination essential for safety to human life.


Now this next is from article 702 Optional Standby Systems



> Optional Standby Systems. Those systems intended to supply power to public or private facilities or property where life safety does not depend on the performance of the system. Optional standby systems are intended to supply on-site generated power to selected loads either automati-cally or manually.


If you must go with article 700 the complexity, requirements and costs increase quite a bit.


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## macmikeman (Jan 23, 2007)

Here is where I see a problem- during extended power outage said 2nd customer building staff adds tie ins to power other equipment and other equipment is also tied to buildings usual grid tie system. Backfeed to utility wiring that has now bypassed the auto transfer switch. This is the reason you do not want to allow your next door neighbor to run an extension cord to your standby generator during a power outage. He may try to cut the end off and tie it into his panel..


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## MEC (Sep 14, 2013)

BBQ said:


> This may help
> 
> This is from article 700 emergency systems.
> 
> ...


Thank you BBQ, The fire station's generator is an emergency generator system. I would be pulling my feeder from that to feed the existing sub panel. That sub panel has the antenna, computers, Phone system, heating and lighting. I had installed this panel and the automatic transfer switch to the generator 8 years ago. It used to be all manual. The maintenance people had added a few circuits like the stove, and kitchen outlets, and also an a/c unit. That would be removed. Like macmikeman said, give em an extension cord and they cut off the end and connect the whole panel.


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## ceb58 (Feb 14, 2009)

As BBQ has said STOP CALLING IT AN EMERGENCY GENERATOR.
Now, with that said if I understand you the loads in the EMS building you want to back up are fed from a sub panel that is connected to the ATS. If so why not just bring your feeders from the fire station and land them on the generator side of the ATS and disconnect the old generator.


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## MEC (Sep 14, 2013)

[QUOTE="ceb58"
Now, with that said if I understand you the loads in the EMS building you want to back up are fed from a sub panel that is connected to the ATS. If so why not just bring your feeders from the fire station and land them on the generator side of the ATS and disconnect the old generator.[/QUOTE]

The ATS is not needed in the EMS building because the feeder from the fire station would have power weather it be utility or generator. There have been instances where the fire station lost power but the EMS was fine and vice versa. Three phase overhead on the fire station section of Main Street, single phase on the EMS section. It's not a big problem to rework the the few circuits, I am just wondering if bringing a feeder from another building into a building with a different power source is common practice.
I have never been asked to do something like this. It doesn't seam right.


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## Bbsound (Dec 16, 2011)

BBQ said:


> Not exactly correct, the building would have two sources of power but only one service.
> 
> 
> A service can only be provided by a utility.


To the firefighter or somebody else in the future that may want to kill all the power to the building, they dont care what the NEC nomenclature is. 
They want to know how to kill the power.


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## denny3992 (Jul 12, 2010)

Bbsound said:


> To the firefighter or somebody else in the future that may want to kill all the power to the building, they dont care what the NEC nomenclature is.
> They want to know how to kill the power.


Labeled disconnect on outside of building does this....


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