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How to wire a 120 volt outlet off a 240 volt line with 20 amp fuse

How to wire a 120 volt outlet off a 240 volt line with 20 amp fuse

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Old 08-19-12, 08:46 PM
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How to wire a 120 volt outlet off a 240 volt line with 20 amp fuse

I recently ran a new line from my home to my water well pump. The line runs approximately 130 ft from a 20 amp breaker. The line is a 240 volt line to the well and it was installed with a 12-2 wire. So there is just a black, white and ground wire.

When the wire gets into the well house it splits and the 240 line continues onto the well pump. Before I ran the new line there was a 120 volt line split off the 240 volt line the wire ran to a 120 volt outlet followed by a light switch run off The same line. Unfortunately I forgot to take a picture if how it was wired and I cant remember how to reduce the 240 line to 120. I know this can be done because i saw it this way befire i ran the new wire but can't find how online.

I believe I should tying all three black lines together, hook just the two whites together to continue the 240 line to the well, and tie the one leftover white from thr 120 volt wire to the copper ground wire set so there would be three ground wires and the white 120v line tied together.

Anyone know?
 
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Old 08-19-12, 08:55 PM
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Welcome to the forums!

I am not following.

You say you ran a 12/2 cable to your well for a 240 volt, 20 amp feed. This is just fine.

Then you say you have three blacks and two whites? Where and how does this come into play? Is there another feed to your well house?

For reference: you get 120 volts by taking one hot and one neutral wire. The ground wire is never used to carry current except during a fault. Doing so will energize all grounded parts!
 
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Old 08-19-12, 09:05 PM
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Welcome to the forums!

In order to restore 120V power to the light and receptacle, you will need a neutral. You don't have one now. The white wire in the 12-2 cable you ran to the well pump has been re-purposed to be the second hot wire for the 240V circuit. Remember, it's connected to the other half of the 20A 2-pole breaker for the well pump in your panel. It should have been marked with black or red electrical tape, or black or red permanent marker, to show that it is not a neutral.

The cleanest way to do this is to run a second cable to well house. Protect it with a single-pole breaker, land its white wire on the neutral bus in the panel, and use it to supply the lights and the GFCI receptacle.

tie the one leftover white from thr 120 volt wire to the copper ground wire set
Do not, under any circumstances, splice any insulated current-carrying conductor to the bare copper wire. The bare copper wire is the Equipment Grounding Conductor, and it is there to safely carry power to ground in the event of a fault. It should never carry any power in normal conditions.
 
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Old 08-19-12, 09:41 PM
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I think Nash may have misunderstood. If the pump is inside a detached structure you can only run one power source to it. If it is a detached structure you will need a 3-conductor (+ground) cable and a subpanel.
 

Last edited by ray2047; 08-19-12 at 10:14 PM.
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Old 08-20-12, 09:25 AM
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Ray is right about the single power run.
 
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Old 08-20-12, 11:09 AM
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If the purpose of the outlet is for outdoor-use such as tools perhaps you could mount it on the outside of the pumphouse or on a post.
 
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Old 08-20-12, 12:11 PM
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I suspect (s)he wants it for a light in the pump house so it is either a subpanel or a 240v light assuming the 240v is on no more then a 20 amp breaker.
 
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Old 08-20-12, 12:21 PM
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If it is a straight 240 volt circuit (two-wire plus equipment ground) then the only way to get a 120 volt circuit is to add a transformer.
 
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Old 08-20-12, 06:45 PM
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The line is a 240 volt line to the well and it was installed with a 12-2 wire.
So, you ran a 12-2 cable. Was it UF cable or NM cable (aka Romex)? Is it in conduit or is it direct buried. By now I think you are aware that you should have run a 12-3 cable.
 
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Old 08-20-12, 07:43 PM
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Thanks for the comments. I cut the original line that came from the main house which was already a 12-2 so I wouldnt have to run all the way to the breaker. It looks like what the person that ran the line before me did was tied the white wire from the line with the lights on it into the ground wires thereby cutting the voltage down. It looks like they "bent" the rules to save having to run a second wire from the house for the lights in the well house.
 
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Old 08-20-12, 08:00 PM
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I cut the original line that came from the main house which was already a 12-2 so I wouldnt have to run all the way to the breaker.
  • What cable or individual conductors did you use?
  • Are they run in conduit?
  • How did you protect the splices you made?
 
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Old 08-20-12, 08:05 PM
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the rules to save having to run a second wire from the house for the lights in the well house.
You can't run a second cable from the house. You can have only one source of power.

We need to know what kind of cable was used. If it was Romex that is another mistake that must be corrected.

Tech note: A wire is a single conductor. A cable is two or more wires in a plastic or metallic sheath.
 
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Old 08-20-12, 08:14 PM
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Anybody hear an echo in here?

Mod Note: LOL
 

Last edited by ray2047; 08-20-12 at 08:31 PM.
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