I just moved into a high-rise condo and on my patio I have an outlet labeled NEMA L15-30-R 90A 250V 30 and I'm trying to figure out what I can do with it.

I think the intended to be used for the window washers who come twice a year.

On my patio, I want to put a lot of electronics (kegerator, fridge, lights, electric heater, electric grill, etc), so is there a way I can get a 110v receptacle out of it?

I am not allowed to remove/replace the outlet, only plug into it.

Also, if you have any other important thoughts, please do tell.

It looks like this: enter image description here

migrated from electronics.stackexchange.com Sep 20 '18 at 11:43


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    In the context of EESE this is an off-topic "usage" question. Try diy.stackexchange Additionally note that even there you will have to specify exactly what you intend to plug in, as a solutions are application-specific. In practical terms, especially for high-consumption items you should probably purchase 230v versions; however also consider that some of what you want may not be safe to install out-of-doors. – Chris Stratton Sep 20 '18 at 1:40
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    @DaveTweed -- you're confusing it with the NEMA L14-30R – ThreePhaseEel Sep 20 '18 at 11:47
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    Yeah. L14 is split phase (fairly common) and L15 is three-phase (less common). There is some slight chance that someone would install an L15 outlet to supply split phase, but it would be a very bad practice in my opinion, ESPECIALLY in a condominium. And I am sure it would be a code violation. You have to walk past dozens of L14 connectors to find the L15 (figuratively speaking). OP might as well measure the phase-to-phase voltage though. That will tell the whole tale for sure. – mkeith Sep 20 '18 at 18:31
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    @AlexK just set your multimeter to AC volts. you're expecting 250v, so set your range appropriately. the holes on the receptacle are labeled X, Y, Z and G. if the labels aren't on there, G is the one with the L shape and the others don't really matter as long as you keep them consistent for your measurements so assign them as you wish. measure the voltage between those holes. you should take six readings: XY, YZ, ZX, GX, GY, and GZ. report those results here. – longneck Sep 20 '18 at 18:49
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    @ThreePhaseEel It may indeed by an L15-30R. They are meant for three phase (haha), so the power present may be three phase, especially for window washing equipment. Regardless, if it's split phase (common 120/240), then it's easy to get two 120V/30A circuits out if it. If it's three phase, just leave it be. It's hard to say any more until you verify what it is. – Hari Ganti Sep 20 '18 at 22:36

No. You can't use this for 120V power. The NEMA L15-30 receptacle is intended for 3-phase power applications. Most likely, it is a 208V three phase power outlet lacking neutral. Because there is no neutral, there is no easy or reliably safe way to get 120V power from it. Even if there were a neutral, it would be questionable whether it would be a good idea to apply a load to only 1 phase. There could be circuitry upstream designed to trip on unbalanced loading.

If you want to confirm that it really is a three-phase outlet, simply measure the voltages from phase to phase. This involves sticking voltmeter probes into the receptacle. There is a shock hazard doing this kind of thing, especially if you are using a cheap multi-meter. If you don't feel comfortable doing it, then don't do it. Please don't blame me if you get shocked.

  • I was going to measure it today and I felt comfortable doing so until you mentioned a cheap clamp meter could get me shocked. I have this one amazon.com/…. Are you saying it's unsafe simply because my multi-meter is cheap? – Alex K Sep 23 '18 at 18:45
  • I would probably do it myself, carefully. But there is a lot that can go wrong. If it was a GFCI outlet, that would be different. But it is a three-phase outdoor outlet. No GFCI. Technically I believe it should be done with CAT IV rated meter. That one lists CAT II and CATIII but I don't believe it. Nor do I believe that the CE mark testing was done. Don't touch the meter during the test. Don't use both hands (keep one in your pocket). Have someone nearby watching. Don't become part of the circuit. – mkeith Sep 23 '18 at 19:04
  • I think I'm just going to give up on the project and run an extension cord. Too risky it sounds like. – Alex K Sep 23 '18 at 19:32
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    There's also a traditional GFCI outlet right below it I could use. I just thought with all the devices I had to a single outlet, it would be better to use a "beefier" plug if it was a simple adapter. – Alex K Sep 23 '18 at 19:40

Condos have specific rules about exterior modifications. You should consultant with the management and usually they are knowledgeable to the existing wiring and additions which could save you a lot of time and money.

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    I'm allowed to use it, but not modify it as it's used 2x a year for the winch on a lift that window washers use. I was hoping to connect some sort of adapter to it and get a standard 110v plug. – Alex K Sep 20 '18 at 16:17

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