Altering 60 amp dedicated circuit in the Garage

Question

I have a 60 amp circuit in my garage with one outlet that was installed by the builder. I want to use that circuit to have a 30 amp outlet for a welder and 20 amp outlet for a table saw. Can I use the wires feeding the current 4-wire outlet to install a sub-box and add a 30 amp and a 20 amp circuit? They would feed their corresponding outlets respectively.

Answer 1

The big question is what you currently have as a 60A outlet. But assuming that you don't actually need 60A (or 48A continuous) from that outlet, the usual solution is to replace the single outlet with a subpanel. 60A is a typical feed for a subpanel. In that subpanel, you can have any combination of:

• 15A and 20A 120V circuits for convenience receptacles (tools, chargers, garage door opener, etc.) and lighting.
• 20A or larger 240V circuits for tools, EV charging, HVAC, etc.
• 20A or larger combination 120V/240V circuits for dryer or other things that need both 120V and 240V

There are a lot of rules for subpanels. But some key ones getting started:

• Space, the final frontier - you need a 30" wide x 36" deep empty space - no permanently installed anything in that space, and no shelving, major appliances or other semi-permanent stuff either
• Neutral and ground need to be kept separate in the panel. Typically panels sold as subpanels will have this by default (but make sure) and panels sold as main panels will have ground and neutral bonded (but make sure), but any new panel can be used either way. Just make sure neutral not bonded to ground/case and all neutral wires on the neutral bar and all ground wires on the ground bar.
• Load calculation - You need to make sure that the expected load will fit in the designated 60A. There are ways to calculate this formally, plus informally by adding up all of the "constant" loads (EV charging, HVAC, etc. that could all be on even when nobody is doing anything) and all of the "temporary" loads (tools, lights, appliances, etc.)
• A subpanel does not generally need a main breaker or disconnect if it is in the same building as the main panel. But it can be a good idea, and simply getting an inexpensive large main panel can make a lot of sense - a 30 space panel might not cost much more than a 12 space panel. Really.
• Almost everything in a garage requires GFCI, except hardwired loads, though it does depend some on NEC version and local rules. GFCI can be provided at the breaker for 240V circuits and at the breaker or receptacle for 120V circuits.

Note that if you currently have a 60A circuit specifically for EV charging, you can install a subpanel and cut the EV charging back to a smaller size (e.g., 30A) in order to make sure you don't overload the panel, without having to actually replace the EV service equipment.

Answer 2

Yes, that's not a problem. In the subpanel you will need to keep neutral and ground totally separate. That means buy an accessory ground bar (if it doesn't come with one) and remove any neutral-ground bonding screws or straps.

However, I am suspicious about your "60A" circuit since there is no such thing as 60A wire. I suspect you have 55A, 65A or 90A wire (90A is at a pricing sweet spot). While it's perfectly OK to have 55A wire on a 60A breaker, I would first want to know to see if I could use a bigger breaker, and second to know how much stuff I could power.

Remember - anytime you have a large 240V receptacle or hardwire junction box point in your garage, before you put your house on the market install signs that say "Level 2 EV charging". Home buyers go crazy for that! This isn't deceptive either: 20-30A is ample for EV charging if it's 240V.