Garage subpanel size

[1995droptopz]

Hello all, I have been lurking in this forum on and off for a while now, and today I finally signed up because I have a question to ask.

I am moving to a new house in the next month or so, and one of my first projects is to install a main floor laundry room, which will be placed in the mudroom next to the garage. There is a basement under the main part of the house, but the mudroom is on a slab. I will have the walls open to install the plumbing and gas lines, so I decided this is probably the best time to wire the garage for all of my future needs.

It is a 2 car garage now, but I would like to extend it in the future. Right now I have an oil less banger air compressor and various hand tools, but would like to upgrade my compressor and get a 220V MIG in the future. Maybe a TIG if I am lucky.

I have a 150A service at the house now. Trying to determine the subpanel size so I can run a welder and have maybe 2 other 20A circuits.

Any suggestions? THanks

 

[grantw]

Honestly, you will want to shop for spaces / capacity versus amperage.

I have 200A service in the new house feeding a 40/80 space panel. The Kitchen and Laundry is getting a 125A 16/32 space panel and will be fed via a 100A breaker. Once the builders are done, I will be adding another matching 125A 16/32 space panel fed by another 100A breaker for just the garage stuff, like my 240V espresso machine, air compressor, etc.

If it's just you in the shop you can oversubscribe your panel all you want. Even if you feed it with a 60A or even a 30A breaker off of your main.

Based on your post, figure your welder, air compressor, lights and maybe a few fans going all at once. Size your feeder with that in mind as your minimum.

in reference to 16/32 spaces or 40/80 spaces, that means it's a 40 space panel, but is listed to support "double" breakers on each stab. Also, whatever panel you are feeding from, check the ratings on how large of a branch / sub you're allowed to feed. If your panel is listed at 60A or 75A per stab, you shouldn't add a 100A breaker to it.

 

[pattenp]

I suggest you use the same brand panel as the house main panel if possible. Also use a main breaker panel instead of a main lug panel to have the convenience of a main disconnect in the garage. Use at least a 20-space/20-circuit panel. You'll be looking at either 100A 0r 125A panels to get more # of spaces. As said by grantw the feeding breaker can be less than the 100A or 125A as that is just the rating of the panel.

 

[1995droptopz]

Good idea on the subpanel for the kitchen. I think there were about 8 or so openings in the panel, but I did not disassemble during the inspection to see if they were capable of using the double breakers. I plan to renovate the kitchen in a couple years, and that might be an easy way to add all the circuits for the kitchen I need.

 

[Bretny]

Do a 100a for your garage. 24 space min. Do it once and never run out of space again.

Just for your welder and a 240v compressor you would take up 4 spaces. Outside lighting 1 space, outlets mabe one space per wall, 1 space for lights. So right there your almost half full on that sub pannel.
Have any plans for a generator, plasma cutter or even a window AC unit?

 

[75gmck25]

My main panel is a Square D QO. I purchased a 100 amp, 24 space, main breaker QO panel for the detached garage, but the breaker in the main panel will be 60 amp, and I don't expect to have more than 10-12 circuits in the garage.

My thought process:
- The 100 amp/24 space panel was easy to find, not much more expensive, and gives me some flexibility for future needs.
- I limited the feed to 60 amp because there is a big price jump when you go beyond 60 amps for QO breakers.
- The wire I'm running between panels is 2-2-2-4 aluminum, which could handle up to 90 amps (more than I need). However, aluminum MHF and SER cable is relatively cheap and easy to find in 2-2-2-4.

In your case, with an attached garage, you should be able to do the entire job with SER cable, and just protect it in conduit where needed (I used MHF to run to my detached garage).

Bruce

 

[nut_buster2017]

I would recommend the largest subpanel your regional codes and personal budget can allow.
The costs to go up to a 60 Amp sub from a 40 sub would be pretty small at the start, but later would be more frustrating than may be necessary.

 

[arkieguide]

We all have our idea of what we need. But be careful making suggestions about places outside your area, as codes differ a lot from place to place. having serviced my union electrical apprenticeship and worked there a few years - the bay area, has its on set of rules / code for electrical work.Just off hand I think anything less then 80 amps will be to small to allow much expansion in the future.