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Garage sub panel checklist

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signcrafter

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Going to start the electrical in my garage shop at the new to us house. House panel is a 200 amp in the basement. Attached garage and sub panel will be about 15 feet of wire from main panel. Going to put a square d qo 24 space main breaker 100 amp sub panel in the garage. Surface mounted on the wall for ease of adding circuits as I go. Main wire will be run in the wall and come in the back of the panel.

Is 6 gauge wire good enough? Service entrance cable the correct cable? Do I need ground rods for sub panel? I will make sure the neutral bar isnt bonded and add a ground bar. Anything else I'm missing or forgetting? Thanks.
 
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nadogail

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6 gauge is not adequate for 100 Amps. Your ground rods will depend on your location and what your local AHJ requires.
 
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mm08822

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signcrafter said:
Going to start the electrical in my garage shop at the new to us house. House panel is a 200 amp in the basement. Attached garage and sub panel will be about 15 feet of wire from main panel. Going to put a square d qo 24 space main breaker 100 amp sub panel in the garage. Surface mounted on the wall for ease of adding circuits as I go. Main wire will be run in the wall and come in the back of the panel.

Is 6 gauge wire good enough? Service entrance cable the correct cable? Do I need ground rods for sub panel? I will make sure the neutral bar isnt bonded and add a ground bar. Anything else I'm missing or forgetting? Thanks.
Click to expand...
The first question is what are the expected simultaneous loads?
Right now many are thinking EVSE's in their future - is it 1, 2, what size/level charger(s)?

You can fit up to a 125A CB in the basement panel depending on feeder size. (125A QO CB is $$$)
At 15' of cable, larger conductors are of minimal cost.
The CB in the main panel has to be sized to protect the conductors feeding the sub panel.
Personally, I wouldn't go smaller than #6.

An attached garage won't require grd rods or a main disconnect in the sub panel.

You may find a panel with main cb on the shelf easier/cheaper than main lug panel.
4 conductors is needed and that would make it SER and not SEU cable. Aluminum SER is sufficient, copper not required.
 
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signcrafter

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nadogail said:
6 gauge is not adequate for 100 Amps. Your ground rods will depend on your location and what your local AHJ requires.
Click to expand...
Not sure why I was thinking 6, it was late when I wrote it. What size is needed? Is 100 amp breaker in main panel the correct size for 100 amp sub panel?
mm08822 said:
The first question is what are the expected simultaneous loads?
Right now many are thinking EVSE's in their future - is it 1, 2, what size/level charger(s)?

You can fit up to a 125A CB in the basement panel depending on feeder size. (125A QO CB is $$$)
At 15' of cable, larger conductors are of minimal cost.
The CB in the main panel has to be sized to protect the conductors feeding the sub panel.
Personally, I wouldn't go smaller than #6.

An attached garage won't require grd rods or a main disconnect in the sub panel.

You may find a panel with main cb on the shelf easier/cheaper than main lug panel.
4 conductors is needed and that would make it SER and not SEU cable. Aluminum SER is sufficient, copper not required.
Click to expand...
No EVs in the near future. Simultaneous loads would be a 3hp compressor if it kicks on along with whatever other machine I'm using at that time, welder, parts washer, table saw, planer, etc. I do plan on putting in a 30 amp RV hookup but it would be it wont be hooked up very often. There will be a reznor natural gas heater so that just needs electrical for the fan. And I may do a smaller AC at some point just to help with humidity in the summer. Just a 1 man shop so while there will be a bunch of equipment in there it will never be used at the same time. Just need help with wire size and breaker size.
 
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signcrafter

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AntonLargiader said:
2-2-2-4 aluminum SER cable for 90A is an easy combo.
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Ok looks like 2-2-2-4 is 5.99 a foot at home depot. I know I've read about the 90 amp breaker before but dont remember where and search doesnt work the best. I didnt see 90 amp breaker at depot, just 100 amp. Can I use 100 amp breaker in main panel to feed sub panel with 2-2-2-4 wire? Or do I have to order a 90amp breaker to put in main panel to feed sub?
 
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wyliesdiesels

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signcrafter said:
Ok looks like 2-2-2-4 is 5.99 a foot at home depot. I know I've read about the 90 amp breaker before but dont remember where and search doesnt work the best. I didnt see 90 amp breaker at depot, just 100 amp. Can I use 100 amp breaker in main panel to feed sub panel with 2-2-2-4 wire? Or do I have to order a 90amp breaker to put in main panel to feed sub?
Click to expand...
no #2 is rated for 90a max unless youre feeding the entire load of a dwelling.
 
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signcrafter

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duneslider said:
My home depot has the 90amp breakers on the shelf. When I saw them I assumed there must be GJ people in the area...the 2-2-2-4 is also regularly sold out...
Click to expand...
Mine only had 100. I'll check menards since that's where I will get the panel anyway. If not I see them online for way cheaper then the 100 amp breaker that depot wants 118 bucks for. Thanks
 
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mike93lx

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Just bump up to 1-1-1-3 AL SER it you want 100a. At 15 feet, I wouldn't spend a lot of time fretting over wire size or special ordering breakers.

Regardless of the feed breaker, you can use any size subpanel you want.
 
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