Tapping 120v from 220v

[Diamondpilot]

You can make a trencher for your 3 point or use something like a potato plow.

Think about this for a minute or two. There is already a cable run to the wellhouse carrying the 240 V needed for the pump. Not only is it underground and out of sight, it goes from exactly the place you want to start your new wire to exactly the place you want to terminate that wire.

Find the existing wire before you even thing about running a trencher or a subsoiler through there.

I guess that was a given but maybe not? He could just as easy just run off the main panel in the house to the new shed and be done with it and not fool around with the wells wiring.

Chris

 

[Mike058]

I can't really tell from the original post how many wires are going to the shed. So if I had wired the shed for a 220v motor, I would have used 2 conductor cable, black and white. I would have put black tape around the end of the white wire to indicate it was not wired as a neutral, but as a "hot" wire. There would also be a bare grounding wire connected to the case of the pump and anything else metal (like boxes).

If I was planning ahead for possibly needing 120v service in the shed at a later date, I'd of used 3 conductor cable with the black, red and white and the bare grounding wire(4 wires total). In that case, the black and red would be "hot" and connected to the separate legs at the service and the white really would be "neutral" being connected to the other white wires at the service. But I'd have a small breaker box in the shed that the 3 conductor would terminate in. Then run two hot wires(probably black and white with the end of the white one taped black) and a bare grounding wire to the pump. You can only get 120v if you have a neutral wire-you can't use the bare grounding wire.

 

[Skyco]

Could also use a 220VAC to 110VAC transformer...for $150 or so one can buy a 2000 watt one...which would handle a "normal" max one circuit 110VAC load.

 

[SPYDERLK]

Could also use a 220VAC to 110VAC transformer...for $150 or so one can buy a 2000 watt one...which would handle a "normal" max one circuit 110VAC load.

Yeah!:thumbsup: ... but what if he comes to want to start a 1HP compressor motor at the shed. I think a 2kW transformer would sag a lot worse than the line. This does have a nice plus tho in that youre only feeding 1/2 the current to the shed at the 220 - and the circuit would stay balanced always. Would have to put in grounding rod at the shed.
larry

 

[nap61]

Thanks for all the replys.
Sorry I took so long to respond but this has been the first time the ground has been dry enough to use my tractor in months.
The well/tank/pressure switch is not in a shed but in the open in the yard. It is about half way to where the shed will be. I opened the electrical connection box at the well and this is what I saw:
1. two wires coming from the main breaker box at the house- one black and one white (which has black tape on it);
2. three wires coming from the well/pump - one red, one black, and one green (which is screwed to a ground screw); the red and black are screwed on a four post buss(?) together with the white and black wires from the main.
I am trying not to run a circuit from the main at the house. There will probably only be a light and maybe one outlet for occasional short term use - no large motors or appliances. My major concern is the well pump. Would having a light on when the well pump turns on starve the pump and damage it?

Norm
P.S. I have a middlebuster to bury the line from the well to the shed.

 

[Obed]

Based on your description, since there are only 2 wires at the well pump, you only have 220V at the well pump; there is not 110V for you to tap off of. Thus you need a transformer to step down the 220V to 110V. If you had had 3 wires at the well pump, you would have had 2 110V legs for a total of 220V and could have tapped off of one of the 110V legs, but you don't have this option. And yes, I would locate the 220V/110V transformer at the shed to minimize the size of the wire needed between the well pump and shed.

Obed

 

[BobRip]

Based on your description, since there are only 2 wires at the well pump, you only have 220V at the well pump; there is not 110V for you to tap off of. Thus you need a transformer to step down the 220V to 110V. If you had had 3 wires at the well pump, you would have had 2 110V legs for a total of 220V and could have tapped off of one of the 110V legs, but you don't have this option. And yes, I would locate the 220V/110V transformer at the shed to minimize the size of the wire needed between the well pump and shed.

Obed

I wonder if he could get a 220 volt bulb. I know this does not help with running something else.

I personally would not do this. Water to my house is too critical to mess with this. However, running a 15 watt CLF off of the well line would have minimal impact. The outlet would be hard to control and somebody may decide to run a "small" electric heater. This would definitely be a problem, but just trip a breaker.

 

[ultrarunner]

I used to come across a lot of old 220v electric ranges wired with 2 hots and a ground AND a 110v convenience outlet on the range top... so, at one time, at least in major appliances... it was possible to get 110 from a 220 circuit.

 

[Obed]

I used to come across a lot of old 220v electric ranges wired with 2 hots and a ground AND a 110v convenience outlet on the range top... so, at one time, at least in major appliances... it was possible to get 110 from a 220 circuit.

What you are describing has 3 wires. What you called the ground is also the neutral. So you have 110v between the neutral and either of the 2 hots. You have 220v between the two hots. The OP only has 2 wires. That's why there's not 110v off of which to tap. Thus the need for the transformer to step down the voltage from 220v to 110v. If he had 3 wires, he would not need the transformer if he only needed to powere a light in the shed.

 

[BobRip]

I used to come across a lot of old 220v electric ranges wired with 2 hots and a ground AND a 110v convenience outlet on the range top... so, at one time, at least in major appliances... it was possible to get 110 from a 220 circuit.

They used either the ground (very bad practice) or there was a neutral running to the range. The neutral is not available here.