Need Help With Wiring/Panel Plan for Detached Garage

[bulletpruf]

Fellas -

In the process of buying a house and installing a 600 sq. ft. garage (22' x 27'?) adjacent to the house.

The contractor was out at the house a few days ago talking electrical service. I need to tell him what I need for a sub panel. Maybe something like 100 amps with 24 possible spaces (48 individual circuits)?

Here's what I'll need to power -

220 Supply for Mini-Split - 30A
Garage lighting - 20A
Garage outlets - 20A (not sure this is enough; I want a lot of outlets)
220V supply for air compressor - 40A
220V supply for welder - 40A
2 Post Life - ?
220V water heater - ?

The main panel on the house is about 75' from where the garage will be. He recommends running the line underground to the garage.

Thanks in advance for any input.

Scott

 

[dscheidt]

100A is enough for a one man shop.

24 space panel should be fine. You have 5 240 loads, that's ten spaces. Two spaces for lighting (overkill, but it makes it easier to change, if you can leave half the lights on). four for convenience 120V outlets. That's 16 breaker spaces. You will want a car charger at some point, so call it 18. That's six open spaces for unplanned loads, which should be fine.

If you're worried about it, the marginal cost of installing a 40 space panel is less than $100.

 

[bulletpruf]

100A is enough for a one man shop.

24 space panel should be fine. You have 5 240 loads, that's ten spaces. Two spaces for lighting (overkill, but it makes it easier to change, if you can leave half the lights on). four for convenience 120V outlets. That's 16 breaker spaces. You will want a car charger at some point, so call it 18. That's six open spaces for unplanned loads, which should be fine.

If you're worried about it, the marginal cost of installing a 40 space panel is less than $100.

Thanks for the details. I may step up to the 40 space panel just in case.

Scott

 

[dcg9381]

220 Supply for Mini-Split - 30A
Garage lighting - 20A
Garage outlets - 20A (not sure this is enough; I want a lot of outlets)
220V supply for air compressor - 40A
220V supply for welder - 40A
2 Post Life - ?
220V water heater - ?

1) I agree, 100A for a 600SQFT shop is plenty unless you're running an electric forge, big AC, and a welder at once...

2) Your mini-split amps are over-estimated. A 24K BTU ductless split will work on a 15A-20A breaker 220V circuit. You won't need a 24K BTU unit.

3) Some breaker boxes support 1/2 size breakers - something to consider.

4) I'd do 2x20A breakers for outlets in the garage. 20A is fine, until you decide to run a refrigerator out there or other device that takes away about 1/2 that circuit capacity.

5) Big air compressor spec'd. Might want to put it outside the shop.

 

[57JoeFoMoPar]

Go absolutely overkill, especially if you can run some circuits yourself. In the grand scheme of things, wiring is cheap. An extra $500 worth of wire, outlets and boxes will save you loads of trouble later on.

Always wire in a heavier gauge than you think you'll need. IMHO all 110v circuits should be 12-2, even if you can get away with 14-2 and a 15A circuit. All 220v lines should be 8 gauge to accommodate 40A breakers. I made the mistake of wiring my shop 220v lines with 10 wire and then when I wanted to buy a 240A welder, I couldn't because it requires 40A input power, and I couldn't run a 7.5 hp compressor. Go overkill and you won't regret it

 

[bulletpruf]

1) I agree, 100A for a 600SQFT shop is plenty unless you're running an electric forge, big AC, and a welder at once...

2) Your mini-split amps are over-estimated. A 24K BTU ductless split will work on a 15A-20A breaker 220V circuit. You won't need a 24K BTU unit.

3) Some breaker boxes support 1/2 size breakers - something to consider.

4) I'd do 2x20A breakers for outlets in the garage. 20A is fine, until you decide to run a refrigerator out there or other device that takes away about 1/2 that circuit capacity.

5) Big air compressor spec'd. Might want to put it outside the shop.

Thanks for the input. Very helpful.

 

[bulletpruf]

Go absolutely overkill, especially if you can run some circuits yourself. In the grand scheme of things, wiring is cheap. An extra $500 worth of wire, outlets and boxes will save you loads of trouble later on.

Always wire in a heavier gauge than you think you'll need. IMHO all 110v circuits should be 12-2, even if you can get away with 14-2 and a 15A circuit. All 220v lines should be 8 gauge to accommodate 40A breakers. I made the mistake of wiring my shop 220v lines with 10 wire and then when I wanted to buy a 240A welder, I couldn't because it requires 40A input power, and I couldn't run a 7.5 hp compressor. Go overkill and you won't regret it

I like the way you think; overkill is how I operate, too.

thanks for the input

 

[shadycrew31]

Don't forget power for the garage door opener(s). Depending on the type 15A service should be fine for both.

Also local Code may require an exterior GFCI outlet and lights over any man doors you have.

For wiring check amazon, I got a 50' 8/2 and 100' 10/2 Romex for $80 less than a big box.

 

[Falcon67]

I run waaay more than what you listed on a 70A line to a 20 slot panel witha 100A main. Which is full now, so bigger would be better LOL.

 

[bulletpruf]

Don't forget power for the garage door opener(s). Depending on the type 15A service should be fine for both.

Also local Code may require an exterior GFCI outlet and lights over any man doors you have.

For wiring check amazon, I got a 50' 8/2 and 100' 10/2 Romex for $80 less than a big box.

Appreciate the input. That's helpful.

Scott

 

[bulletpruf]

I run waaay more than what you listed on a 70A line to a 20 slot panel witha 100A main. Which is full now, so bigger would be better LOL.

Good input. Thanks