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I asked this question here and got some great answers. As mentioned in the previous question I have a pump that is 350ft (as the wire runs, probably closer to 370ft) from my house, that pumps water up my hill. The specs for the pump are as follows:

Rated power - P2: 1 HP
Main frequency: 60 Hz
Rated voltage: 1 x 115 V
Maximum current consumption: 8 A
Power plug: US plug 115V

I've decided to do as the answer on that question suggests, and use a 2 pole 15 amp breaker, and run the full 350 ft using 12/3 cable. Then I need to step down from 240V to 120V since that's what my pump uses, and I want to plug a few other things in at the bottom of the hill (everything other than the pump is super low draw, like LED lighting).

I can find step down transformers all over online, but nothing that seems right based on the answer from the original question. They recommended a

a small encapsulated (NEMA 3R rated) 240V/120V stepdown (1500VA is fine)

I've gone to a few electric stores this morning, and nobody seemed to know what that means (admittedly, I am not an electrician, and neither are the guys working the counter). However, they did have Hammond control transformer 50 VA, 1-phase, 120/240 VAC panel mount. They had these in many different VA's including 50 VA, 100 VA, 350 VA, 1000 VA, 1500 VA, etc.... Other than these, I can't seem to find anything that is already encapsulated in weatherproofing (unless the price jumps significantly...like, from $100, to $800.)

It's likely I'm not looking for the right thing, and could use help on suggestions on what kind of step down I need. I don't mind mounting one of these in a weatherproof box, but I'm not entirely sure which VA I need. I know the original answer said 1500VA, and that one does exist in a store near me. But, is this the right thing to get, and then just buy a waterproof box for it?

EDIT

This one meets the description given in the original answer, but I was a bit confused because it seems cheaper to get this one inside of a case, than outside of the case.

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  • I would go with 10/3 wire. With a two pole breaker you do not really need a step down. A regular sub panel will work. 240 to the panel and single breakers on that panel to get 120v circuits. Does not matter the size of the sub panel rating as long as it is bigger or equal to the feed breaker. A 100 amp panel fed by 15 amp breaker is okay.
    – crip659
    Commented May 7 at 16:57
  • @SolarMike That is a thing that is highly idiosyncratic to the UK. They simply do not exist in the US where the OP is.
    – nobody
    Commented May 7 at 23:30
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    @crip659 Please read the context. The OP needs to power a 120V pump at a very long distance. If they don’t step down at point of use, they have to deal with 370 feet of voltage drop at 120V, whether they run two hots and a neutral or just one hot and neutral.
    – nobody
    Commented May 7 at 23:35
  • @nobody doesn't stop the transformer existing, just because you don't like it...
    – Solar Mike
    Commented May 8 at 4:26
  • @SolarMike It’s not a matter of liking it or not. The point is it’s a complete waste of the OP’s time to mention something that simply does not exist on this continent.
    – nobody
    Commented May 9 at 1:25

1 Answer 1

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Yes that transformer linked in your edit looks like a good choice. Page 4 of the data sheet illustrates that you'd install a jumper wire between H1 and H3, a separate jumper between H2 and H4, and connect the two hot legs (240 V source) to H1 and H4. On the load side for 120 V output install a jumper between X4 and X2, another between X3 and X1, and connect lines to X1 and X2.

C1F series transformer wiring

This will seem a little foreign: neither side of the transformer secondary is "neutral" by design or definition. You get to choose. Sink a ground rod or other suitable electrode in the earth, call that "earth ground", and connect either X1 or X2 to it. This is your ground-neutral bond, and from this time forward the X terminal you picked is called "neutral."

We can only guess why it may be priced lower than the bare transformer: maybe there's higher margin in the other product or maybe their raw costs are higher, maybe the one in the 3R enclosure faces more competitors/price pressure, or maybe the one with the 3R enclosure just sells in higher volume and this brings its price down.

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