Subpanel & Electrical For tools

Just scored an oneida 3hp unit which needs a 20 amp 220v circuit. Super excited to get it going but then found out bad news. In my current sub panel it had appeared that I had space for 3 circuits, which I was going to run one dedicated for DC and the other two for various tools throughout garage. I plan to only run one 20' or so run with two circuits on it for 220 and just have long chords for each tool. Don't have a large space just a normal 2car space. After inspecting more and getting into the panel, I only have one spot. My question is can run another sub-panel be ran off of the current sub. The main panel and current sub are side by side and I should have space to just add another. Anyone ever do something like this?

Of course just make sure to follow bonding rules for the grounds and neutrals. It might make more sense to mount you new sub panel farther away from the existing subpanel. I mounted my subpanel on the opposite end of the shop from the first panel. it saved me in the reduced length of medium size wire needed saved more then the cost of the extra #8 supply to the subpanel.
Watch Craigslist for used cable and panels.

"The main panel and current sub are side by side and I should have space to just add another. Anyone ever do something like this? "

Is this the Main Service Panel, the first panel that power comes to from the pole, or underground service? If so, just replace the current sub panel, with a higher rated panel, with more poles.
You can absolutely sub, off an existing sub panel. There are codes that need to be adhered to, but if your main service panel and the subpanel are side by side, the code requirements get much, much, easier.

The other comment I'd make is that there are half size breakers which allow you to have more circuits in a panel. Depends on what size wire you have serving the sub-panel whether this makes sense or not.

As Mike C. suggested, I'd probably replace the sub panel with a larger one and maybe larger wire servicing it.

Mike

I agree with the others...a new, larger sub-panel would be what I'd do simply because it's going to cost you about the same as a third small one, more or less, and it keeps the complexity down. The feeder to the sub may need to be re-sized. It would be a good idea for you to consult with a licensed electrician to ascertain what's necessary to make this change, even if you choose to do it yourself and have the appropriate knowledge/skills/experience to do so safely. Where you live matters, too...some jurisdictions may give the hairy eyeball to a property owner doing their own wiring. (Yea, I know, many folks would ignore that anyway, but it still has to be said)

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Originally Posted by Jim Becker

Where you live matters, too...some jurisdictions may give the hairy eyeball to a property owner doing their own wiring. (Yea, I know, many folks would ignore that anyway, but it still has to be said)

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And it should be said!

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Originally Posted by Zachary Caldwell

Just scored an oneida 3hp unit which needs a 20 amp 220v circuit. Super excited to get it going but then found out bad news. In my current sub panel it had appeared that I had space for 3 circuits, which I was going to run one dedicated for DC and the other two for various tools throughout garage. I plan to only run one 20' or so run with two circuits on it for 220 and just have long chords for each tool. Don't have a large space just a normal 2car space. After inspecting more and getting into the panel, I only have one spot. My question is can run another sub-panel be ran off of the current sub. The main panel and current sub are side by side and I should have space to just add another. Anyone ever do something like this?

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Heck yeah!

I'm a huge fan of a sub-panel dedicated to the shop, having had two panels in three houses (moved the first one).
-- The biggest reason is that it draws a bright line between the house wiring (done by the pro) and shop wiring (done by me, the weekend warrior). Electricians love the idea.
-- I put a big cutoff switch with a fuse (belt and suspenders) between the main panel and my sub. The cutoff serves two purposes
1. it's a big red emergency switch. the young ones are trained early to pull the big red lever if somethign goes wrong.
2. it lets me isolate my sub-panel and wire stuff without any fear of getting bitten.
-- I get lots of breakers. Most of my machines have dedicated breakers. My current sub has 24 breakers. Most are still blank.
-- It's removable. If you move your shop, you take your sub-panel down and all your shop wiring and take it with you. When we moved from our last house, I had my electrician friend remove the sub-panel from the main and it was if the shop was never there.

I had an electrician install the first sub-panel (twice). This one, I did myself because the electrical contractor just didn't want to do it. Their quote to run 3' of wire was $900. My general contractor called that an, "I don't want to do it price". The electrician on our project saw what I did and declared it ok. He just wasn't allowed to work on it.

Be sure to keep your neutral and ground buses separate in the subpanels. (They should be bonded only in the main, primary panel.)

Good idea to replace the existing sub panel and move it farther downstream. As long as it is not Zinsco or FEDERAL Pacific. Try to get a new panel that uses the same make and model of breakers so you can shift that around as wire size allows.

My city had a weird rule (they no longer give any code info online) for panels. No permit was needed to replace a large panel maybe 100 amps or more. For smaller panels you had to pull a permit. I guess they figured no harry Homeowner would switch out a 100+ amp main panel.
Bil lD