I may need a subpanel: how to figure

[rick carpenter]

I need more outlets in my garage. I don't really need more power at the same time just more outlets, and the main panel is filled. I currently have three outlets in the garage, a gfci on the back wall where power comes in, a gfci on the workbench wall, and one regular outlet in the ceiling. I'm thinking at least two more outlets on my workbench wall, one on the front of the garage for outdoor power equipment, and a weatherproof outlet on the side of the house. I may take up welding (not in a big way, just projects) if I can learn how, but the laundry room is backed up to the garage which gives me 240V well within the range of a welding extension cord if I do that. So do I need a subpanel?

If so could I take the 'garage' circuit from the main and use that to feed the sub? How do I figure how many amps? And while I'm at it I'll need to convert the first outlet to a regular one since my garage refrigerator runs off of it, right? I think I read here that a fridge shouldn't be on a gfci.

 

[Norcal]

All 15 & 20A 120V receptacles in a garage require GFCI protection with NO exceptions.

 

[pattenp]

Buy good quality GFCI outlet not something from the dollar store or some cheap non brand over the internet. If you don't need more load capacity then extend the existing outlet circuit.

 

[mike93lx]

Does your panel accept tandem breakers? If so, that is a lot easier and cheaper than a subpanel when you just need a few more circuits

 

[bmwpowere36m3]

If you just need more outlets then add them to the existing outlets in the garage. IIRC, there is no limit to the # of outlets on a branch circuit.

 

[Norcal]

If you just need more outlets then add them to the existing outlets in the garage. IIRC, there is no limit to the # of outlets on a branch circuit.

In residential only, other occupancy’s there is a limit.

 

[bmwpowere36m3]

In residential only, other occupancy’s there is a limit.

Including attached and detached structures in residential, assuming garage/shed/barn?

 

[75gmck25]

Based on your initial question, I'm not sure if you are willing to run new wiring. That makes a big difference, since it sounds like the current circuit is only a standard 20 amp NM cable to the garage.

Assuming you are willing to run a new cable, just replace the current 20 amp breaker with the proper amperage breaker, and run cable to the sub-panel match the amperage. For example, you could use a 50 amp breaker with copper 6/3, or you could use a 90 amp breaker with AL 2-2-2-4 SER. 6/3 would probably be a lot easier to fit if you are trying to use the existing wire path.

Sub-panels are relatively cheap if you buy the common versions that are stocked in the big box stores. In most cases you can ignore the max panel rating if its higher than you need, since your amperage limit will be determined by the breaker in the main panel. For example, you could run a 50 amp breaker in the main panel, and 6/3 wire, but use a 100 amp sub-panel just because it was available at good price. Get a sub-panel that uses the same breakers as your main panel so you don't have to keep track of two brands.

Bruce