Two feeds to detached garage/shop

[txa79]

I have a detached garage at a rural weekend house. I am planning to turn the garage into my workshop, but existing electrical service runs underground to the garage from a 30 amp breaker in the main service panel at the house. It's fed with 10 guage wire to a small sub-panel in the garage, branching into three 120v circuits...lights are on one circuit, and a few plugs are on the other two circuits. No issues, everything works just fine. However, I want to add capacity so that I can run a small 240v stick welder, a 240v grinder, and a few other power tools. (Of course, it's just me, so they will only be used one at a time.)

My Question: Can I add a second sub-panel in the garage and feed it from a 50 amp breaker in the main house panel, and then install circuits for my welder and other tools? I would leave the existing 30 amp sub-panel and circuits in place. So, in other words, are there any issues regarding having two (2) circuits feeding two (2) sub-panels in the detached garage, both being fed from the main service panel?

This is my first post ever. I hope I am making my question clear!

 

[Stuart in MN]

Multiple branch circuits to a detached garage are not permitted per NEC article 225.30, except for a few special conditions (emergency systems, fire pumps and a few others.) If you need more capacity you'll need to run a new branch circuit and install a new sub panel that's large enough to handle both the existing and new circuits. You can leave the existing sub panel in place if you like, just feed it from the new sub panel.

 

[Terry D]

As far as my understanding, you can not have 2 electrical supplies feeding the same building ,yet. The 2020 NEC has changes about that, I believe only one state has adopted it. I would run a new service for sub panel large enough for all your loads in the garage and just do away with the small 30amp sub.

You will need a 4-wire feeder and a sub panel with a main breaker to serve as a disconnect. Keep your neutrals isolated from the grounds and install 2 ground rods

 

[txa79]

OK thanks guys. My motive for leaving the old sub panel was due to the fact that the garage has been sheetrocked and I didn't want to have to bust it out to re-wire. The little 30 amp box is in a terrible location, and there is a better place for the new one. I don't know why I didn't think of just feeding the old sub panel from the new one. That would be easy and wouldn't require any real "re-wiring". Glad I asked. Thank you both!

 

[wyliesdiesels]

Run a new 4-wire feeder, connect to new subpanel and then feed old panel from new panel

Make sure to connect 2 ground rods to new subpanel and isolate the neutral bar in the subpanel.

Is the existing feeder 3 or 4 wire? If its 3-wire, you will need to convert it to 4-wire which means isolating the neutral bar.

 

[astroracer]

Put in a 125 amp panel, do it to code and feed the old panel like has been mentioned. If you have the capacity in your main panel feed the new one with a 100 amp breaker. There is no reason not to and you will never want for additional power in your one man shop.
Mark

 

[nadogail]

I am still learning about the limits of my knowledge.
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