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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.

praiseHellRaiseDale
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1 Answers1

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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.

Greg Hill
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