Garage/Shop Sub Panel Service

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Old 10-07-09, 05:30 PM
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Garage/Shop Sub Panel Service

I have a woodworking shop in the third bay of a 3 car garage. I want to add a sub panel from my main service panel. My main service panel is a combination meter base and breaker panel. The breaker side of the service panel has 6 slots for double pole 240V. breakers. I have one spare left that I would like to add a 100 amp breaker/disconnect. I would like to put a 100 amp sub panel in the shop. I purchased a Square D 125 A. panel with 8 single pole spaces or 4 double pole spaces. I plan to use all spaces for 240V. breakers. I plan to power up my rotary phase coverter on a dedicated 50 amp breaker. I have a stick welder I would like to put on a dedicated 50 amp breaker. The other two breakers would be 30 amp used for receptacles for my various 240 volt woodworking equipment. Being an architect, I asked my electrical engineer about a service wire to the sub panel. He said to use 2-2-2-4 Aluminum wire to serve this panel. I have to run the service wire about 65 feet through my attic. I also have the option to run copper but it is siginificantly more expensive than the aluminum and my local code jurisdiction allows aluminum. I under stand this service must be coated with an antioxidizing coating and torqued at both panels. I must run the service wire in conduit up the side of the house and enter through the roof soffit. Here are a few questions...

1. Is 2-2-2-4 aluminum service wire adequate for this panel considering there is a 65 foot run? Should I get 1-1-1-4 but is tough to work with.

2. My main service panel being a combo meter base and breaker panel can not be de-energized. There is no main breaker between the sides. This means the new breaker will need to be wired with the panel hot. Sounds like a job for an experience electrician, or have the service company pull the meter...

Any help is greatly appreciated.
Thanks Eric
 
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Old 10-07-09, 06:25 PM
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Originally Posted by ejc49 View Post
1. Is 2-2-2-4 aluminum service wire adequate for this panel considering there is a 65 foot run? Should I get 1-1-1-4 but is tough to work with.
You did not really specify what kind of wire/cable your planing to run. (XHHW or USE) but either way you need to run #1 to get the full 100 amps. While #2 XHHW is rated at 100 amps under the 90 degree most lugs you will connect the wire to are only rated at 75 degree or less. (Info you should pass to your EE )

Originally Posted by ejc49 View Post
2. My main service panel being a combo meter base and breaker panel can not be de-energized. There is no main breaker between the sides. This means the new breaker will need to be wired with the panel hot. Sounds like a job for an experience electrician, or have the service company pull the meter...
You are correct. In order to de-energize the panel the meter will likely need to be pulled. This will have to be done by your POCO. Or like you said, have an electrician come out and do it.

I also suggest bringing back the panel you have and get a panel with more spaces. Only 8 spaces is quite limited and since you have them all spoken for already you are painting yourself into a corner. You should be able to get a Square D 100 amp panel value pack (one with a main breaker is fine) for around $50-$75. That should get you about 16-24 spaces and some 20 amp breakers to boot!

You also didn't mention if this is attached or detached garage. If it is the latter, you will need a ground rod.
 
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Old 10-08-09, 06:31 AM
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Originally Posted by Tolyn Ironhand View Post
You did not really specify what kind of wire/cable your planing to run. (XHHW or USE) but either way you need to run #1 to get the full 100 amps. While #2 XHHW is rated at 100 amps under the 90 degree most lugs you will connect the wire to are only rated at 75 degree or less. (Info you should pass to your EE )



You are correct. In order to de-energize the panel the meter will likely need to be pulled. This will have to be done by your POCO. Or like you said, have an electrician come out and do it.

I also suggest bringing back the panel you have and get a panel with more spaces. Only 8 spaces is quite limited and since you have them all spoken for already you are painting yourself into a corner. You should be able to get a Square D 100 amp panel value pack (one with a main breaker is fine) for around $50-$75. That should get you about 16-24 spaces and some 20 amp breakers to boot!

You also didn't mention if this is attached or detached garage. If it is the latter, you will need a ground rod.
Tolyn, Will the wire size be size by what year code they are using? 2005 code # 1 would be OK for 100 amps but the 2008 code he would have to use the 60c range IF he's using SER wire and that would only be good for 90 amps. Just trying to learn something here.

Jim
 
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Old 10-08-09, 08:04 PM
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I didn't mention anything about SER but since you pointed it out, if you use any nonmetallic sheathed cable you may only use the 60 degree column. Which would mean you would need to run 1/0 for 100 amps.

Looking at my 2008 and 2005 codebook I do not see any special listing or article for SER so I'm assuming it would fall under the NM article.
 
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Old 10-08-09, 08:31 PM
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Originally Posted by Tolyn Ironhand View Post
I didn't mention anything about SER but since you pointed it out, if you use any nonmetallic sheathed cable you may only use the 60 degree column. Which would mean you would need to run 1/0 for 100 amps.

Looking at my 2008 and 2005 codebook I do not see any special listing or article for SER so I'm assuming it would fall under the NM article.

Tolyn.,

It will be under the NM article it mention something like that in 2008 NEC code cycle.

Merci,Marc
 
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