I have a 30 amp 2 pole breaker in my main panel (in garage) that supplies a sub panel in my small workshop (back yard) ~ 100 ft run 4 wire 10GA. for 15 amp outlets.

In order to add this 30 amp circuit, I had to replace several of my 15 amp singles with 15 amp tandem breakers to make room.

I would like to add a 240v outlet near my main breaker panel in the garage for a welder. Can I add this inline with the sub panel circuit, or would it have to have it's own 2 pole breaker too?

Thank you, Aaron

  • 2
    you can't upgrade your main panel to a larger model? Mar 23, 2017 at 16:14
  • Sounds like a bad idea to me.
    – Tester101
    Mar 23, 2017 at 16:47
  • What are the nameplate specifications on your welder? Mar 23, 2017 at 22:17
  • How often do you need to switch? Is there space near your main panel to locate a new subpanel? Is your 30A 2-pole breaker a plain 2-pole breaker, or is it 2-pole duplex (a 2-pole in the middle and 2 single-poles on the outside or another 2-pole on the outside)? Mar 24, 2017 at 4:26
  • I don't yet have a 240v welder, this is planning ahead at this point. I was hoping to avoid adding another sub panel, but I think I could if I had to. Would The breaker supplying the out building sub panel is a standard 2 pole C&H ... It looks like 2 single with the tgoggles barred together. The conduit for this Line runs right by the location I would most likely want the new outlet. Which is where the idea came of chaining an outlet in like is done with 120 outlets on a branch.
    – Aaron
    Mar 24, 2017 at 15:52

1 Answer 1


You need another subpanel

Being out of breaker spaces is an intolerable situation. This invites all sorts of problems - you might balk on installing AFCI breakers because they won't fit; you might inadvertently move an old MWBC onto a tandem and burn your house down.

So what you really need to do is install a subpanel right next to your main panel and start moving circuits over to that. This time, get a large panel. No one has ever written a post on SE saying how they're having problems because they have too many panel spaces. Get a 30-40 space minimum. The moment of buying a service panel is the worst possible time to suddenly develop an urge to save $40.

I recommend looking at panels of good quality (not bottom shelf big box store dreck) for which GFCI and AFCI are affordable (not CH or QO).

Then, it becomes super easy.

As you observed, this question would be a no-brainer if you had the spare panel spaces. Either put this new breaker in the new panel, or move enough 120V circuits to the new panel and put it in the old panel.

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