GOAL: installing an external 240v wall outlet to power a future air compressor. I have attached a picture of the electrical panel in my house. I would like to understand what I am looking at in the panel. I do not know how to find the main breaker to stop the feed of current/voltage to this panel. Lastly, do I even have room to install a breaker that is suitable for a 240v air compressor. I am happy to be here and learning from everyone, first question asked, so please correct me in any way and school me up. I am thirsty so if you have time just lead me to the water!

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  • Your main breaker is probably outside at the meter or another panel. Right now we don’t have enough information, you can probably add a sub panel and take 2 of the breakers out of that panel move them into a sub then feed the sub from that location, I would want to know the size of the service prior to suggesting anything (how many amps on the breaker in the main that feeds this panel).
    – Ed Beal
    Commented Jul 28, 2020 at 16:33
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    If you can carefully push some of the wiring out of the way to get a clear picture of the label on the right side of the panel, that will help the experts here. Also, it's concerning that there are no wire clamps on any of those punch outs.
    – FreeMan
    Commented Jul 28, 2020 at 17:00
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    Yikes! I see a number of issues here: 1) There are no cable clamps on any of the cables coming into the box, over the years, insulation can get scrapped away and cause shorts. 2) The neutral conductor isn't code taped white (not a huge deal). 3) No main breaker. I assume the top right breaker is for a range. In the picture I can't follow the main feed lines so can't comment on that. And no, you don't have space for another 240 v breaker in this panel unless you change out something else. Commented Jul 28, 2020 at 17:11
  • Can you include a straight on photo of the panel, specifically the lower right side?
    – JACK
    Commented Jul 28, 2020 at 17:28
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    @FreeMan I would be money those are feeding pure 240V loads (that don't use neutral). x/2 cable only comes with black and white wires (not black and red) and it's legal to use that way. Code didn't even require marking of white wires whose use as a hot was "obvious" until recently.
    – nobody
    Commented Jul 28, 2020 at 17:50

1 Answer 1


Can you install a new 240V breaker? Probably. It looks like the necessary two spaces are available on the bottom-right (the one space on the left side can only get you 120V without shuffling things around).

Pictures of that areas straight-on would be helpful, as would pictures of the panel front and the stickers on the inside left and right sides of the box.

Since there is no shut-off in this panel, it must be somewhere upstream - probably in the same box as your electric meter. You'll want to take a look and see what the amp rating of your feed is, as that could limit whether you could run this new load at the same time as all your other existing loads. Judging by the wires feeding the bus bars, you probably have 100A service to this panel.

For an outdoor receptacle, you'll need GFCI protection somewhere in the circuit - either in the breaker or the receptacle. Receptacle GFCI can be less expensive than breaker GFCI, but may not be available in the size you want. It's also not a great idea to mount sensitive GFCI electronics outdoors.

There are some other concerning issues in your picture:

  • No grommets/clamps around any of the cables entering the box. Without proper clamps, the cables may rub against the sharp edges of the knockouts until the insulation is cut and a short circuit occurs.

  • Probable missing handle tie on the breakers in spaces 5 and 7 (left side, below the double 30). Judging by the lack of visible numbers on those handles and the black and white load wires, those two are probably feeding one 240V load and used to have a handle tie. You don't want to be able to turn off only one leg to the load, as it creates a dangerous situation where the device appears to be off but still has live wires inside. A handle tie ensures you always turn off both legs together.

  • Probable missing handle tie on the breakers in spaces 15 and 17. Also, the wire is far too small to normally be on a 50A breaker (it looks like probably #12, good for 20A or maybe #10, good for 30A), although there are code exceptions for certain motor loads (such as air conditioners) that mean it could be a legitimate configuration.

  • At least two of the screws in the neutral bar have two wires. There should only be one neutral wire per screw. Grounds can generally be doubled up.

  • The orange cable should not be flopping out in the open air. It should be fastened securely, and protected from damage (e.g. covered by wall or conduit below a certain height, which it is surely below if the panel is mounted at a legal height).

  • The ground wire in the bottom-left corner of the panel (the one mostly wrapped in paper) looks like it isn't connected to anything.

  • Thank you for responding. I am new to this forum so bare with me. Learning the etiquette as I go. This was the house I grew up in, both my parents have since passed away. I am not sure when the house was built, but was purchased in late 80's early 90's. I have a lot to look up from your answer, as I do not understand a lot of the jargon/terminology. I did take a look at the electrical meter but could not see anything that resembled a breaker, only black ground wires. Again I opened up this panel for the first time in my life, this morning. Commented Jul 28, 2020 at 18:24
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    Note that BR is not the same as CH. the breakers will not fit each other. Commented Jul 28, 2020 at 20:05

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