New 40A or 50A Sub-Panel for Garage (Replacing 30A Old Panel)

[Model A Fan]

I have a 30A panel in my garage currently, its a 6 space Square D QO panel. There's nothing wrong with it, but I'd like to have more breakers available and have a bigger panel with more amperage available. I have a very common replacement panel, Square D Homeline with 40 slots. I'd like to run a new sub-panel feeder of 40A or 50A and was trying to figure out which type of wire to use. With 40A, I'd use an 8/3 and 50A I'd use 6/3, both copper. The distance is possibly 60', up the wall inside the house into the attic space, across open attic and then punch through the wall into the garage, to the garage ceiling/rafter area down into the sub-panel.

What kind of wire would I need for this application? I was figuring NM-B would suffice:

6/3 NM-B

or

8/3 NM-B

If photos of the spaces are needed, I can get those no issue. Would it be foolish to go with 40A-8/3 due to the cost in wire being about $100 more for the 50A-6/3? I don't think I'd power anything more than my Miller 211 or small air compressor. Thanks!

 

[wyliesdiesels]

AL SER will be cheaper than cu NM-b

for about $85 + tx and shipping (or maybe find it locally) you can get #4 AL SER. will give you 65a

4-4-4-6 Aluminum SER Cable (By-the-foot)

4-4-4 Aluminum SER Cable w/ 6AWG Ground

www.wireandcableyourway.com

If you step it up to #2 you can do 90a and it will cost you aout $115 + tx and shipping

2-2-2 Aluminum SER Cable w/ 4AWG Ground

2-2-2 Aluminum SER Cable w/ 4AWG Ground

www.wireandcableyourway.com

 

[75gmck25]

I would also recommend 2-2-2-4 AL SER, since it's usually less expensive, and can handle up to 90 amps.

I used a 60 amp breaker with mine because the lower amperage breaker was cheaper and easy to find in stock locally. IIRC, I got the SER wire from Home Depot because they had a reasonable price at the time, but now it's usually quite a bit cheaper from the online stores.

 

[gimpyrobb]

Like buying a welder, go with the largest you can reasonably afford.

 

[mike93lx]

I would definitely use aluminum ser. Copper is too damn expensive for this application.

I agree on #2. One and done

 

[PhantomEB]

Definitely go overkill in supply as well the breaker box.

 

[Model A Fan]

Thanks guys, I'll actually get this one here:

https://www.platt.com/p/0062444/ser-service-entrance-cable-2-3-aluminum-1000/739373024657/23sergx1000

Its cheaper than having it shipped and I can get it locally. Lowe's is out of it currently and other shipping options start at $37 to ship.

Should I do an even bigger breaker even though I'll never use that high of amps? I am unsure if there would be any benefit, and the cost would be high.

 

[mike93lx]

Thanks guys, I'll actually get this one here:

https://www.platt.com/p/0062444/ser-service-entrance-cable-2-3-aluminum-1000/739373024657/23sergx1000

Its cheaper than having it shipped and I can get it locally. Lowe's is out of it currently and other shipping options start at $37 to ship.

Should I do an even bigger breaker even though I'll never use that high of amps? I am unsure if there would be any benefit, and the cost would be high.

After 60a is where the price jumps, so that's what I would do. Exceeding 60a in a single person shop is not common

If your usage doesn't trip a size and your wire fits in it, going larger is of no benefit. A 60a homeline accepts #2, so you are good to go