Get two 120v circuits from one 240v circuit?

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Old 04-15-17, 11:36 AM
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Get two 120v circuits from one 240v circuit?

If you have a 240v 4 wire circuit (hot, hot, neutral, ground) and the 30 amp breaker it currently has was replaced with a 20 amp breaker, is there a code conforming way to "split" the hots at the outlet to provide two 120v 3 wire 20 amp circuits?

I'm thinking some sort of adapter must exist to do this, unless there's a safety reason why this would be a terrible idea that makes it against code.
 
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Old 04-15-17, 12:00 PM
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That is the basis behind a multi wire branch circuit.
You would remove the 30a breaker and install a 2P20A breaker like what would be used for a 240v circuit.

The neutral is shared between the two circuits. It can be as simple as a wire nutted splice.
In this type of circuit.... the neutral is very important so ensure that a good splice is made.

Just one wiring example.....
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Old 04-15-17, 01:08 PM
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I was asking terms of whether it would be possible to get the 30A breaker replaced with 20A, but leave the existing 240v twist lock receptacle in place (I think it is L14-30) Then use some sort of adapter that would have a L14-30 male plug on one end, and provide two standard 5-15 or 5-20 120v female plugs on the other for ordinary 120v stuff to plug into. The adapter would basically be wired the same as your diagram.

Due to subsequent remodeling where the receptacle is located it would be very difficult to get at it to change, let alone add a second one. It is hard enough to access to plug/unplug stuff into it! I was hoping there might be a way where the only electrical work was replacing the circuit breaker, and there was an adapter I could buy rather than huge difficulty (and big $$$ I'm sure) of having the receptacles changed as in your diagram.
 
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Old 04-15-17, 01:25 PM
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Receptacles are made to avoid someone plugging in to an incorrect voltage or ampacity. The devices should be changed.
 
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Old 04-15-17, 01:41 PM
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If such an adapter split the two hot legs between the two 5-15 female plugs (i.e. one to each) and sharing the ground and neutral, how would it be possible to plug in the incorrect voltage or ampacity? You'd have 120v 15A plugs, each effectively on its own circuit, same as if you rewired it as in PJmax's drawing.
 
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Old 04-15-17, 02:56 PM
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Are you talking generator here???

 
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Old 04-15-17, 03:21 PM
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I wasn't talking generator, but that appears to be exactly what I was after! Checking a few places that sell a similar looking generator adapter, it is indeed able to take a generator's 240v L14-30 output and split it between to separate 5-20 circuits, each getting one of the 240v circuit's hots. So it would work on a 240v household circuit in the same way (I will still have the 30A breaker replaced with 20A for safety, even though I'm pretty sure I'd never exceed even 15A on either with what I want to plug in)

I figured something like this had to exist, but I didn't know what to ask google for. Thanks!!
 
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Old 04-15-17, 04:37 PM
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IMO if your running cord from that outlet change the breaker to GFI or make/buy and cord with GFI's in it..

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