I'm in the USA. I'm wanting to use two different 120v 15A plugs that are on different circuits at the same time to charge my car. I'm thinking of creating a hub adaptor that is the inverse of what is below.

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Where there would be two male NEMA-5 plugs reconciling one female NEMA-5. Since current always flows to the female, I would plug my car's charge cable like normal (which is rated for much higher loads than I would ever encounter).

Should this work? Is there anything I'm failing to consider?

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    No no no! No no no no no! 100k rep expert here. That is a catastrophically bad idea. You'll get reasons soon, but the short version is given all the work, it's not that much farther out of your way to do the job properly. Nov 4, 2019 at 15:13
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    Now, tell us about the existing circuits into your garage, and the type and how much space you have in your panel (a photo will do)... and a sense of the level of difficulty of running a new cable from panel to garage(just so it can be weighed against other options). Nov 4, 2019 at 15:15
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    Do not even think of going where you propose. There are a lot of reasons with good scientific basis as to why this is not safe. One reason is that operating two circuit breakers in parallel on one circuit load can never have a guarantee that the load will split evenly between the two breakers. The moment one of these breakers decides to trip on an overload the other breaker and its wiring will be expected to carry the full load which may very well be over the safe operating specification for the wire. So again STOP with this idea.
    – Michael Karas
    Nov 4, 2019 at 15:33
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    There's also the neutral. Current will favor one path over the other, so they won't load evenly. A breaker will keep a hot from overloading, but neutral is unprotected because the entire design philosophy of the system is neutral only handles return current for its companion hot. We're only scratching the surface of the bad-idea-ness here. Nov 4, 2019 at 15:57
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    @GabrielFair The good news is that if you post: a) Picture and details of existing breaker panel; b) type of car/charger c) location (country/state/city - it can be quite relevant to determine types of permitted wiring and other stuff) and possibly other details, we can probably help you come up with a solution that won't cost a fortune and will be safe & code-compliant. Nov 4, 2019 at 17:36

1 Answer 1


No one is focusing on the code we should be saying we need to be referencing the national electric code. NEC 625.40 electric vehicle branch circuit . Each outlet shall be a dedicated circuit and have no other outlets. So simply stated the answer is NO it cannot be done the way you want. This reason and about 20 other different reasons as others have indicated.

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