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#33734 - 01/27/04 10:25 AM Generator Systems
Dublin1 Offline
Junior Member

Registered: 01/27/04
Posts: 2
Loc: Appleton Wisconsin
I have a residential customer with a 400 amp service that has a 43KW backup natural gas powered generator installed at his home. this generator is housed in a detached garage which also houses, a pair of riding lawnmowers, 4 four wheelers, 4 snowmobiles, and the biggest longest motorhome I've ever seen, as well as numerous gas containers, kerosine containers, and kerosine space heaters. Over the last few years he has also added to the detached garage another 1900 sq feet which includes a living space, bathroom, gameroom and attic storage. This addition has its own 200 amp service. Now for the questions, what code problems are we looking at in this application, what safety concerns, what about the possible negative pressure effects, not to mention no panel labling to indicate more than one service supply to this building. Also the owner would like to add several circuits from the detached garage addition to the generator via another tranfer switch. Can this be legally done? Thats about it for now, what do you think??

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#33735 - 01/27/04 02:28 PM Re: Generator Systems
PCBelarge Offline

Registered: 06/08/03
Posts: 657
Loc: Dobbs Ferry, NY, USA
Two separate service sources to the same generator, from different buildings?

Two separate services feeding the same building? 230.2 - I do not see how A through D applies here.

I would not be comfortable with this project, I am not sure, as I cannot see this job, but something sounds 'fishy'.

Pierre Belarge

#33736 - 01/27/04 06:06 PM Re: Generator Systems
russ m Offline

Registered: 02/22/03
Posts: 165
Loc: Burbank,IL,USA
I don't see the code violation/s. Somebody must have allready allowed the second service to the detached garage. I don't see any problem feeding parts of the two diffrent services with one generator.
As for the fuel storage, That's could be a problem. I just don't know if it's a NEC problem.

PS I think they (THE SERVICE MAINS) should be labeled, if there are circuits from both services in the same building

[This message has been edited by russ m (edited 01-27-2004).]

#33737 - 01/27/04 06:12 PM Re: Generator Systems
DUBLIN Offline

Registered: 09/23/01
Posts: 19
Loc: Menasha, WI, USA
Yes it would in fact be two separate service sources to the same generator from 2 separate buildings. The main house with a 400 amp service is about 200 feet from the detached garage. The original detached garage was supplied power from the house via a 100 amp sub-panel, this garage houses the 43KW generator and supplies emergency backup power to the residence and detached garage. Now the owner had an addition attached to the detached garage, this addition exceeded the capacity of the 400 amp service on the house so it could not be supplied power from the original sub-panel in the detached garage. Following so far?? This is an 18,000 sq ft single family residence, dad,mom,and 2 sons.
As to the second question of 2 separate services feeding the same building... technically yes. The original detached garage supplied from a sub-panel powered by the house panel, and the addition to the detached garage powered by a new 200 amp service.
230.2 C 2 and 230.2 C 3 were originally offered as suffient cause by the local authority according to the owners documentation.
The main reason for the contact with the owner was the lack of a generator maintenance program. The usage of the garage housing the generator is what has opened this can of worms.
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#33738 - 01/27/04 07:21 PM Re: Generator Systems
russ m Offline

Registered: 02/22/03
Posts: 165
Loc: Burbank,IL,USA
Again the generator inside is not unusual as long as it is exhausted properly. If it's a fuel storage problem, it time to move the fuel.

#33739 - 01/30/04 03:18 AM Re: Generator Systems
Scott35 Offline

Broom Pusher and

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
43KW for a House?! Dang!!!

I worked on a Go-Generation project, where two 60KW Generators with Gas-Turbine Prime Movers (using the Utility type Natural Gas), were used. This was within a 4 floor Commercial Office Building, and load calcs showed this 120KW would be ample for normal usage, plus some overhead to be sold off to the PoCo.

Just wanted to say a few things...


P.S.: The setup also used an evaporative chiller, which took the "wasted" heat energy and applied it to heating the Building's Water - in conjunction with a Storage type Water Heater.
Great idea on the reuse of as much energy possible!
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!


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