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#20421 - 01/14/03 12:06 AM Putting in a disconnect for generator help please?  
jlhmaint  Offline
Member
Joined: May 2002
Posts: 202
Fredericktown, OH, U.S.A
Can you guys send me in the right direction. Guy at work ask me what size of a disconnect he would need to put in so that he could put in a generator in garage and feed his house.

What is code on this and were is it at in code book i havent had chance to look up and havent had much exposer to this but have also considered doing this at home.

I am industrial electrical maintenance man and haven't had much residential experience. but i do have code book and follow best i can at work and have 8yr experience but i don't want to tell him anything wrong and i think he wants me to do the work.


Work Gear for Electricians and the Trades

#20422 - 01/14/03 12:12 AM Re: Putting in a disconnect for generator help please?  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Not enough info, but the disconnect would be based on the generator size.

More important is how to keep the two power sources separate.

Do not back feed the utility, you can Kill linemen.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#20423 - 01/14/03 12:19 AM Re: Putting in a disconnect for generator help please?  
sparky66wv  Offline
Member
Joined: Nov 2000
Posts: 2,232
West Virginia
Jerry,

To make things simpler, you can get a transfer switch board that has 6 circuits (for 20A 120/240V plug on genny) or 10 circuits (for 30A 120/240V genny) and are set up for 4-wire portable generators for ease-of-installation.

[Linked Image]
pic source

If they already have the generator, size the transfer switch board, twist-lock plugs and SOW cable for the size of the largest 120/240 V outlet on the genny, and there you have it.

The pairs of lines and loads are numbered and get hooked in series with the breakers to the circuits you want on the genny. The neutral and EGC go the the proper busses.

Connect the cord and you're all set!

The grounding electrodes of the dwelling are used and no other rod is needed.

Now, if they want to run anything over 20A, then I'm no help and go see the thread I started tonight!

-Virgil

PS: If I have any of this wrong, PLEASE correct me! (I'm testing myself to see if I have all this straight)

[Linked Image]

[This message has been edited by sparky66wv (edited 01-13-2003).]


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

#20424 - 01/14/03 12:28 AM Re: Putting in a disconnect for generator help please?  
jlhmaint  Offline
Member
Joined: May 2002
Posts: 202
Fredericktown, OH, U.S.A
sparky thanks for the info

iwire that is what i was wondering about don't you have to put in a disconnect before lets say the home 200amp panel so you can disconnect from the utility company so that you dont back feed the line and at what % is this sized compared to the say 200amp panel.


#20425 - 01/14/03 12:43 AM Re: Putting in a disconnect for generator help please?  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
jlhmaint,
sparky66wvs Info is great and is cheaper by far then full-sized transfer switch Manual or Auto.

Transfer switch size would be based on highest current from either source so
200 amp main panel 30 amp Genset = 200amp transfer switch. Expensive and you still would need to buy more.

Reliance Makes a couple of panels 100 and 200 amp that have 2 mains 1 for Normal 1 for emergency that are mechanically interlocked so only 1 can close at a time.
UL listed for GE Square D and Siemens Breakers.

More Money then Gen Tran switch less then transfer, good solution for larger Gensets
and limited space



[This message has been edited by iwire (edited 01-13-2003).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#20426 - 01/14/03 12:49 AM Re: Putting in a disconnect for generator help please?  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
If you have not worked with them, a transfer switch is just a double or triple pole, double throw switch that separates normal from emergency automatically or manually


Bob Badger
Construction & Maintenance Electrician
Massachusetts


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