Electrical Power to 240V Well Pump

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ka4koe

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An architect friend of mine wants to provide power at a well pump house for a 120V filter. The problem is he has 240 volt power only with no neutral. The existing 30/2 (1 HP) circuit consists of two phases + ground, with no neutral. Now, the well pump filter he is buying requires nil power @ 3W but is 120V. He also wants to pull a 120V GFCI circuit to an adjacent shed for a light and convenience receptacle. My options are...

1. Repull a new circuit to the well pump house using UF cable, Phase A, Phase B, Neutral, Ground. Derive 120V from this circuit via a small load center in the pump house. The run is approximately 150'.
2. Provide a small encapsulated step down 240/120V transformer (less than 500 VA load) to derive 120V for the well pump filter and any convenience outlets. Can someone make a recommendation for where to obtain such a small, light duty transformer?

Suggestions??

Thanks

Philip Neidlinger
 
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Option 2. Don't forget the grounding electrodes, and you still need the small load center or fused disconnect. May be as easy to up size the transformer for full load and set a load center with CBs to feed well and misc load.

Customers fall over at the price, when the well/pump installers just connect to the EGC for the neutral, it is impossible to compete.

Real PIA. If we could just get them to bury a 4 wire in the first place.
 
ka4koe said:
...
2. Provide a small encapsulated step down 240/120V transformer (less than 500 VA load) to derive 120V for the well pump filter and any convenience outlets. Can someone make a recommendation for where to obtain such a small, light duty transformer? ...
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I would do it with your option 2, but consider (or consult with the user) on the inherent limitations to using a 500VA transformer or less to feed that GFCI convenience receptacle. You will have to put a fuse on the secondary because a 15A CB is not going to protect that transformer. So every time he plugs in his power drill or weed whacker, he will blow that fuse and curse you and your children and their children. I would use at least a 1kVA transformer, and STILL let him know that the power is somewhat limited, but you could get him a 10A QOU breaker (or some other small load center with a 10A breaker if you can find one) that he could at least reset if he over loads it.
 
ka4koe said:
He also wants to pull a 120V GFCI circuit to an adjacent shed for a light and convenience receptacle.
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Jraef said:
I would do it with your option 2, but consider (or consult with the user) on the inherent limitations to using a 500VA transformer or less to feed that GFCI convenience receptacle. You will have to put a fuse on the secondary because a 15A CB is not going to protect that transformer. So every time he plugs in his power drill or weed whacker, he will blow that fuse .
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If he wants to use real tools out in the shed that would require real power.

I would talk with the friend and see what his long term plans are.

If you do need to run power out to the shed don't bother with UF cable. Go ahead and run 1" PVC out to the shed and this will have him covered for anything in the future. 150 ft of PVC isn't expensive it's the trenching that cost.

I hate trenching so any time I have to dig I only plan to do it once in this life time.
 
On my own 11 acre property, I have had a couple of UF wires fail, probably due to gophers or such. I will never bury another one, from now on it is 1 inch or larger pvc conduit w/ thhn. A little more money, perhaps, but far better when something doesn't go wrong, or when you need to add something.
 
GoldDigger said:
How about THWN instead? If the pipe comes out of the ground outside a building the inside of it is a wet location.

Tapatalk!
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My mistake. It is duel listed wire, and I just have gotten into the (bad) habit of referring to it as THHN.
 
ptonsparky said:
Not a mistake. I would be surprised to find any sole rated THHN in this area.
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Well, what you can buy off the rack at Big Orange out here is solely listed as THHN. Actual supply houses are another story. To get wet rated you have to go to a cable type instead, although they might be willing to do a special order.
 
GoldDigger said:
Well, what you can buy off the rack at Big Orange out here is solely listed as THHN. Actual supply houses are another story. To get wet rated you have to go to a cable type instead, although they might be willing to do a special order.
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Really the rolls I have are all dual rated.
 
May be regional or store variation. At my HD not only are the rolls on the shelves single rated, so are the big spools on the rotating rack.

Tapatalk!
 
ptonsparky said:
Option 2. Don't forget the grounding electrodes, and you still need the small load center or fused disconnect. May be as easy to up size the transformer for full load and set a load center with CBs to feed well and misc load.

Customers fall over at the price, when the well/pump installers just connect to the EGC for the neutral, it is impossible to compete.

Real PIA. If we could just get them to bury a 4 wire in the first place.
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Customer gets even more upset when an inspector somehow gets involved later in the game and they now have to change that "cheaper installation".:happyyes:

GoldDigger said:
Well, what you can buy off the rack at Big Orange out here is solely listed as THHN. Actual supply houses are another story. To get wet rated you have to go to a cable type instead, although they might be willing to do a special order.
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How much you willing to bet the only difference in products is the marking itself - and maybe the price they managed to get for it?
 
Yes he would.

I would use the original feeder as a 240v feeder to transformer. Secondary would be 240 (X1 to X4) with X2,X3 grounded. Transformer would have to be sized for the total load but with the allowable over current protection you can stretch things a bit to make it all work.
 
darekelec said:
Does the OP have to ground one of the legs on secondary of the transformer?
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Maybe not but that is probably the easiest, least complicated and less expensive way to do it. An ungrounded system is possible, but would require ground detection. Such systems are generally only preferred for processes that may be more harmful should they be shut down unexpectedly though. Indication of a ground fault will alert users there is a problem that needs attention but does not immediately open circuits, which allows equipment to continue to run until it can be shut down in an orderly fashion. Now if there becomes another fault on another conductor of the system it will cause overcurrent devices to open anyway, and is one reason you should investigate the problem ASAP when the first fault is detected.
 
GoldDigger said:
May be regional or store variation. At my HD not only are the rolls on the shelves single rated, so are the big spools on the rotating rack.

Tapatalk!
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What brand wire are you getting from the HD?
If it is either Essex or CERRO those are both dual rated. I know the spool says in big print THHN and then off in the corner in small print it says THWN. The CERRO website says it's dual rated also using the part number on the spool.
 
It is mostly Southwire. I took another look and although nothing on the shrink wrap says anything but THHN, the fine print end label on the spool and the wire itself lists THWN and several other codes that might be European.
Just took a closer look.

Tapatalk!
 
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