wiring problem/40amp to 20amp

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Old 12-18-17, 09:19 PM
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Question wiring problem/40amp to 20amp

I have 3 40amp breakers that were installed for tankless water heater. New wiring was routed leaving the 3 40's unused. My shop/garage in in need of additional outlets. Can I convert 40amp to 20amp. Wiring is black & red with white ground?
 
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Old 12-18-17, 10:39 PM
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Welcome to the forums.

You want to convert the old wiring to run on a 20A breaker.
That cable is black, red and white..... no bare ground ?
 
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Old 12-19-17, 07:11 AM
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White should be a neutral. Are the circuits run in metal conduit where perhaps the conduit served as the ground?
 
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Old 12-25-17, 03:39 AM
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[gave bad info.. there is a bare ground, the white wire is capped off. need to have standard 120 power to the outlet. need 20a because a 15a keeps throwing the breaker if two or more items and lights are on
 
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Old 12-25-17, 03:46 AM
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The white will need to connect to the receptacle. Check to make sure it is connected in the panel. You will also need the ground.
 
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Old 12-25-17, 08:42 AM
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I'm going to guess the 40A circuit used #8 copper and you are looking to use the existing wire to serve the 20A outlet(s). You may find that #8 is the max size to fit in a 20A breaker or may be too large. So it may be necessary to splice on some #12 to wire to hook up the breaker and will definitely require some #12 to hook up the 20A 120V outlet(s).
 
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Old 12-28-17, 11:43 AM
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my original post was wrong. after carefully checking electrical panel there is a bare ground wire , the white wire is capped off
 
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Old 12-28-17, 07:00 PM
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Is this an attached garage?
 
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Old 12-29-17, 08:59 AM
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no, garage/workshop is in the basement of my log home. the wiring is black, red with bare ground and a white wire capped off
 
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Old 12-29-17, 03:27 PM
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If there's #8 already nicely run downstairs with a ground, I'd be tempted to throw a small (cheap) subpanel in the basement/shop. Seems like a waste to do it the way you're planning, only getting 1 20A circuit out of the deal. You never know what kind of power-hungry stuff you'll want to use in your workshop later on.
 
 

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