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I'm confused about the power available to me by looking in this breaker box. I'm thinking of leasing this space, which is an office/retail shop.

Wall outlets have both 120 and 240 volt outlets. Owner does not know if 240 wrks but assumes it does. Breaker box has 2 breakers that say "30" on them, and below that two areas that say 10 kA 120/240V.

I've been reading about "double pole", and I don't think this is since it would have one bar going across both breakers. Does this look like 2 separate 30 amp circuits at 120v (totaling 60 amps @ 120v), but if you use a 240v outlet, it would be the equivalent of 30 amps because the two combine? (Or 15 amps each circuit?) What is the yellow bar at the bottom?

When it reads 30 amps per circuit, I've read that really means maybe 24 amps are available. Does this mean I can't plug in something that says it requires 30 amps?

I have a piece of equipment (forced air tunnel dryer) I may want to purchase in the future, and the requirements are single phase 1750 Watt 30 amp 240 volt. Would this work on this system? And if so, would that mean I can't plug anything else in?

Currently I have two heat presses, each need 1750 watts 15-20 amps 120 volt. Can I plug both of these in the system? I would assume yes, and I might have a small amount left over for other things.

The owner unfortunately is no help, and I'm trying to figure out this all myself. Thanks for your help in advance!

SEE PHOTO HERE: breaker box

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    Looks to me (but I'll leave it to the Square D experts who will know in an instant) like you currently have 2 x 30A 240V circuits. If wired to receptacles as you describe (which sounds like an MWBC 120 + 240) then you have a problem because ordinary 120V circuits need 15A or 20A breakers. The panel seems to have some more spaces in it, so that may be fixable without a huge expense, but needs to be figured out before you start plugging things in.
    – manassehkatz-Moving 2 Codidact
    Commented Mar 9, 2021 at 22:37
  • @manassehkatz-Moving2Codidact Agreed + . OP will probably need to install a couple of breakers (15, or 20A). I think this panel was for something very specific, but, like you said, could be easily re-purposed for the OP's needs. EDIT: And, yeah, you're right in that you can't turn a 30 amp circuit into a MWBC.
    – George Anderson
    Commented Mar 9, 2021 at 22:43
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    Seems unlikely that any office/retail space would be built with ONLY this supply. There is probably another breaker box somewhere else and this box probably only serves one or several special-purpose outlets. If the owner is no help it may be because the other breaker box is inaccessible to you. Does this space appear to have been subdivided? Whatever odd arrangement is being offered to you may be against code. In an empty retail shop, assuming you're not Macy's, the breakers should be pretty easy to find!
    – jay613
    Commented Mar 9, 2021 at 23:07
  • Yeah, there should be another breaker box somewhere...
    – ThreePhaseEel
    Commented Mar 10, 2021 at 0:00
  • I went and looked up the numbers again on the equipment I have now, and what I may buy in the coming year. Currently I am using two heat presses. I would need to plug these in immediately. These need to be on their own circuit. HOTRONIX® AUTO OPEN CLAM 120 v; 15 amps; 1800 (per heatpress). The one piece of "future" equipment I may purchase but do not use now, would be a BBC Forced Air dryer. It's always on heat. It needs/uses: 240v•1Phase•7,250W•30A
    – Mika
    Commented Mar 10, 2021 at 0:04

2 Answers 2

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These are 2-pole GFCI circuit breakers, possibly model QO230GFI as seen here.

https://www.se.com/us/en/product/QO230GFI/

The "yellow bar" is a test button.

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Not quite: You have 2 30 amp breakers at 240v, which means 60 amps at 240v and 120 amps at 120. It's an usual configuration, probably for some specific purpose in the past. Are you sure there isn't another panel that feeds lighting and other 120v outlets?

Regarding 24 amps, vs 30, you are talking about derating for continuous loads (like lighting and heating). I DK if your equipment is considered a continuous load or not...something for you to investigate. If in doubt, do the derating to be safe.

EDIT: adding to my answer based on @manassehkatx comment...you'll need to get some 15 or 20 amp breakers to run "convenience circuits" from this panel. You can't turn a 30 amp 240 v circuit into a MWBC.

Lastly your comment about getting a piece of equipment that requires "1750 Watt 30 amp 240 volts" doesn't make a lot of sense to me, perhaps a typo? Even a derated 30 amp 240v circuit could handle up to 5,760 watts (30 x 240 x 80% = 5,760) so, I'm not sure what the manufacturer is up about.

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    Large motor loads are often like that -- they need a large surge of current to get spinning initially, and once they're there, they draw much less power. It probably specifies a 30A breaker because the inrush current would trip a 20A, but once it's going it only uses the 1750W it specifies.
    – Nate S.
    Commented Mar 9, 2021 at 23:08
  • The one piece of "future" equipment I may purchase but do not use now, would be a BBC Forced Air dryer. It's always on heat. It needs/uses: 240v•1Phase•7,250W•30A
    – Mika
    Commented Mar 9, 2021 at 23:57
  • Currently I am using two heat presses. I would need to plug these in immediately. These need to be on their own circuit. HOTRONIX® AUTO OPEN CLAM 120 v; 15 amps; 1800 (per heatpress).
    – Mika
    Commented Mar 10, 2021 at 0:03

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