Problem getting 120v circuit off 240v hot tub sub panel

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Old 05-16-17, 10:27 AM
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Problem getting 120v circuit off 240v hot tub sub panel

I am not an electrician but have pretty extensive experience with DIY projects including some electrical. I'm stuck:

I want to run a 120v circuit off my hot tub sub panel to run some string lights.

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In the picture attached, the circuit I am adding is coming in from the bottom left: black, green, white. I put the white to the common bar, green to ground, and with the black (in the pic it is not attached and just has a wire nut on it), I pigtailed it to the red leg of the 20A two-pole breaker. Outside the sub panel, I first installed a 20A GFCI outlet and as soon as I power the sub panel from the 50A breaker at the main, the 20A two-pole breaker in the sub panel trips. The second thing I tried is to replace the 20A GFCI outlet with a standard 20A outlet and the interesting thing is that it did not trip the breaker at first, but only when I plugged something into the outlet.

Any help is appreciated. Thanks. (sorry picture is rotated - can't figure out how to fix that)
 

Last edited by ray2047; 05-16-17 at 10:51 AM. Reason: Rotate image.
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Old 05-16-17, 01:04 PM
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Yes, there is 240 between red and black coming in. Also the panel has been working fine and running the hot tub for about 3 months now.
 
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Old 05-16-17, 01:35 PM
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Also the panel has been working fine and running the hot tub for about 3 months now
Is it a 120 volt hot tub?
 
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Old 05-16-17, 01:46 PM
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No, the tub is all 240. I'm not sure why there are two separate 240 breakers feeding the tub but that's how it was installed by an electrician. The tub is fancy and has multiple jet speeds, lights, etc.
 
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Old 05-16-17, 01:50 PM
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Technically since that panel only has room for 2) two pole breakers and they are both feeding the hot tub.... you can't tie a 120v circuit in.
 
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Old 05-16-17, 03:12 PM
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Yeah, Pjmax, I am aware I was cheating a little and that it would not meet code. I'm not too worried about that. Thanks.
 
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Old 05-16-17, 04:48 PM
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Those both look like GFI breakers. That means you can't tap a 120v load from either one as that will unbalance the circuit and trip the GFI.

On a 2 pole GFI breaker.... you have to draw an even load across both legs. A 240v load by its nature does that.
 
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Old 05-16-17, 05:08 PM
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Bummer. I guess that means upgrading the sub panel. Well, thanks for the advice!
 
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Old 05-16-17, 07:40 PM
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Does the power in cable have a common (neutral) white conductor?

Without that you will need to string a new cable with red, black, white, and ground to the new subpanel.
 
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Old 05-16-17, 09:59 PM
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The breakers are the expensive part so find a panel where you can reuse those breakers.

Yes... there is a neutral there. A black wire taped white. :NO NO NO:
Either that wasn't inspected or the inspector missed the black wire taped white.
By code that wire is supposed to be white as any THWN smaller than #4 cannot be remarked.

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Old 05-17-17, 03:56 PM
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On a 2 pole GFI breaker.... you have to draw an even load across both legs.
No you don't. 120/240 appliances never draw evenly because the 120v part is only connected to one leg.. It's tripping because the neutral is connected to the neutral busbar instead of the neutral (center) screw on the breaker. The breaker needs to be able to meter flow through the neutral in order to detect an imbalance.

I'm not sure why there are two separate 240 breakers feeding the tub
The 30A is for the heater, and the 20A is for the jet pump.
 
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Old 05-17-17, 04:50 PM
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taz420 wins. My son-in-law was at my house working on it this morning and that's exactly what he figured out. He connected the neutral to the center screw on the breaker and it works fine now.

Thanks all for your comments and advice.
 
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