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timmed 04-04-2011 04:11 PM

Using half of a double-pole breaker.
I have a 50amp/240V Spa GFCI disconnect panel on the back of my house. I no longer have a spa, and the panel is not being used for anything. I want to add a 20amp 110v outlet next to the panel.

Is there any issue with borrowing 1 of the hot wires from the panel, along with the neutral and ground? I would just put a cap on the other hot wire. I know the voltage would be right, but my concern is that the breaker back in the Main panel is 50amps, so it would take a lot to trip it.

Thanks in advance.

Dahammer 04-04-2011 04:25 PM

I'd replace the disconnect with an outdoor subpanel with a couple circuits in it. You can pick up a 2/4 70 amp outdoor subpanel new at Lowe's for $20. That way you can size your breaker as you want. Either that or replace the breaker in the main panel with a single pole breaker of the correct size.

teamo 04-04-2011 04:31 PM

You are right in that the breaker is too big to trip a 20 amp circuit. The 50 amp breaker is protecting the wire that is there now. The easiest thing to do would be to replace the breaker with a 20 amp breaker but the wire is likely a #6 and I am not sure that it would fit a 20 amp breaker. You could replace the spa disconnect with a small sub panel and install a 20 amp breaker in it and run your new circuit from there.

timmed 04-04-2011 05:05 PM

Thanks for the replies, gentlemen. I like the idea of the outdoor subpanel, and will pursue that. Just for the sake of curiosity, would it have caused a problem to use just one half of that double-pole breaker? I know the amperage of the breaker was too high, but beyond that using 1 hot wire would just be a normal 110v right?

AllanJ 04-04-2011 05:37 PM

Simply using one half of a double breaker is not a problem.
You will get the 120 volts.

But ordinary lights and receptacles must be protected by breakers not greater than 20 amps, hence the idea of a subpanel.

Red Squirrel 04-04-2011 06:44 PM

If you're going to do that, may as well use the whole breaker and make it a MWBC. But since the breaker is over 20 amps I'd just go with the mini sub panel idea mentioned.

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