supplying electric service to garage

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Old 10-12-09, 01:30 PM
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supplying electric service to garage

I just built a new detached garage and need to run electric service to it from the house.

What I have at the house to supply the garage:
Two panels with 100 amp service each and two meters
One panel was a dedicated electric heat and all breakers were 220. Right or wrong I removed all electric heat and switched wiring so all breakers only supply 110 and added some 110 outlets where the old electric heaters were and added several new outlets for home office lights and computer. So in my mind there is not much load on this 100 amp service anymore and should be my best bet to supply the garage. The Garage is approx 35 ' from house electric service.

What I need to power in the garage:
2 - 1/2 horse GDO
6 - 4' florescent or 6 100 watt lights which ever fits into my scenario best.
1 - 1/2 hp air compressor
8 - 110 receptacles
2 - 60 watt outside light fixtures
1 - double 150 watt each flood light fixture motion sensing.

What I would like to know:
What kind and size of wire to run to garage? I plan on burying in conduit of some kind 18" deep.
Can I run 100 amp Sub panel service to garage with its own main switch and will 5 circuits be enough?
What size wire to use in garage, 14 or 12 gauge?
Any other suggestions are very welcome.

In advance I would like to say THANKS!
 
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Old 10-12-09, 03:18 PM
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Originally Posted by camelotWI View Post
I removed all electric heat and switched wiring so all breakers only supply 110
If you pay different rates on the meters it could eventually be a problem with the power company. If you were interested in investigating that...

So in my mind there is not much load on this 100 amp service anymore and should be my best bet to supply the garage.
That sounds right.

What kind and size of wire to run to garage? I plan on burying in conduit of some kind 18" deep.
PVC conduit is the most appropriate for this -- 3/4" would be okay for up to 60A, 1-1/4" for 100A. The cost isn't that much more to go with the larger size just in case.

The type of wire to use in the conduit are THWN individual conductors in black, black (or red), white and green (or bare).

The sizes would be #8,8,8,10 for 50A, #6,6,6,10 for 60A, or #3,3,3,8 for 100A.

Can I run 100 amp Sub panel service to garage with its own main switch and will 5 circuits be enough?
You could, but I think 100A is really overkill for your needs. You could do a 50A and still have plenty of room for expansion if you ever wanted to do a shop or other power tools.

I would do the following circuits:
1) 20A both GDOs
2) 15A all lighting interior and exterior
3) 20A air compressor and maybe some receptacles. 1/2HP isn't that big to require a completely dedicated circuit unless you might get a bigger one someday.
4) 20A general purpose receptacles
optional 5) 20A more general purpose receptacles

Please also study Bruto's subpanel diagrams as they convey a lot of necessary information: http://forum.doityourself.com/electr...-drawings.html

What size wire to use in garage, 14 or 12 gauge?
I prefer to use #14 wire 15A circuits for lighting and #12 wire 20A circuits for receptacles, however that is not a requirement. You could just buy one roll of #12 and do everything with that.

Note that all receptacles in the garage must have GFCI protection, even the ones on the ceiling for the GDOs and shop lights.
 
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Old 10-12-09, 04:12 PM
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thanks excellent information!

ibpooks,

Thanks and thanks again this is very helpful and I will be sure to check out the electric bill for difference in rates. Don't need a BIG surprise electric bill or legal complaint. The diagram 4 wire sub panel detached building really simplified things.

Have a great day!
Beer 4U2
 
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Old 10-12-09, 05:48 PM
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CamelotWI.,

If you tell me which POCO you have I can able determed if you have mulit tier rate or not and their regulations due I deal few diffrent POCO in my area so I am pretty famauir with their " bleu book " aka regulation book

As far for Ibpooks he got it covered with the details what you need.

However with WI Comm 16 { state electrical code } everything in detached garage have to be GFCI'ed expect 240 volt circuits it still not GFCI yet

Merci,Marc
 
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