Whitenuckler
Minister of Fire
I know for you 230/115 should be available surplus as they are used in control panels. Look on ebay.
power flickering from small 12vdc -> 120vac inverter attached to EV
- Thread starter RustyShackleford
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Bingo, thanks, yes lots available on ebay. Probably gonna go with this ebay for $80 (see below).
Yes, I have to reverse feed it, and I actually found a document from the manufacturer says it's ok:
ACME dry-type distribution transformers can be reverse connected without a loss of kVA rating, but there are certain limitations.
Transformers rated 1 kVA and larger single phase, 3 kVA and larger three phase can be reverse connected without any adverse
effects or loss in kVA capacity.
This is the un-enclosed version of it, so I'm a little worried about safety. I should probably find an enclosure for it. Safest is to put it by the well-head; that's sending the 120vac probably 125ft on 12awg wire, so maybe as much as 5v drop. But given the pump is spec'd for 240v max and my house voltage is typcially 123v, that's probably a good thing (in fact, I'm probably over-driving it now). Would need to find a NEMA 3R enclosure.
Attachments
![[Hearth.com] power flickering from small 12vdc -> 120vac inverter attached to EV](/talk/data/attachments/347/347018-1d1b84e6fb824250c918c5c4b5b9fdde.jpg?hash=x9Liy3OCZl)
Whitenuckler
Minister of Fire
If you are sending 240 volts out you don't need to worry about voltage drop on the supply cable from your house. If you send 115V out then you will have more volatge drop. I'd mount it near your panel so you can make all the connections there. You are only going to use it once and awhile.
I'd probably put it by the pressure tank and pressure switch, in the crawlspace. My plan is to have it permanently installed; my well runs off a 20amp/120vac circuit from now on. Why not ? It's simpler. Or by the well-head; like I said, that voltage drop that far with 120vac might be a good thing. The rated voltage of the pump is 200-240vac.
Less voltage drop is always better for a motor than more. Your motor is happy on 240v and would probably be even happier on 250. Put the transformer at the beginning of the run and ahead of the switching. You don't want to be dealing with transformer inrush and motor inrush simultaneously.
Liking this power station: https://us.ecoflow.com/products/del...BwE&gbraid=0AAAAABKED1xfMQPwr1rgQ9x4dIBdBSHEn
Only $600 factory re-furbished. One worry: the AC power is supplied on six 120vac outlets. I dunno if it's ok to pull the entire 2400 watts out of one outlet, which is what I'd want to do connecting to my generator inlet. Or if it's ok to parallel two or more of those outlets.
Only $600 factory re-furbished. One worry: the AC power is supplied on six 120vac outlets. I dunno if it's ok to pull the entire 2400 watts out of one outlet, which is what I'd want to do connecting to my generator inlet. Or if it's ok to parallel two or more of those outlets.
Even though the spec says rated voltage is 200-240 vac, and company guy told me speed does not start to drop until well below 200vac ?
There is no motor in-rush, well at least there's no surge, are they the same thing ? But yeah, putting it by the panel or in the crawlspace means the transformer is always energized, putting it by the well-head does not.
Safety concerns are mitigated if I only put transformer online during outages, but it's much simpler to always have it online (replace the current 15amp/240vac breaker with a 20amp/120vac one).
EbS-P
Minister of Fire
Seems to indicate that 20 amps is the total capacity and does not indicate a small per receptacle limit.
What I meant to say was, out of spec at the high end is less bad than being out of spec at the low end, and you should not stress about running it at 240 +/- 10%. I'd rather do that than create voltage drop on purpose which will waste energy and increase the motor's current draw.
Does the motor have a soft start? Even with a soft starter I bet there's a bit of inrush even if you can't measure it.
Switching on the transformer while it's loaded, I dunno, you might get away with it. Depends how well your inverter can handle the starting current. You could always add a 1 second delay module with a contactor for the pump motor if it doesn't work.
Yes, it's absolutely a soft-start motor. I never measured more than 5amps (with a clamp-on current probe for my Fluke 87 meter).
So you're strongly in favor of the transformer being before the pressure switch, whether that means it's at the load center or at the pressure tank.
With soft start it's definitely less of an issue.
Starting up a transformer while the secondary is essentially shorted (or pulling LRA of the motor) can and does cause breakers to trip, especially if the supply voltage isn't stable. However, leaving the transformer constantly powered introduces a nonzero amount of continuous power use and I don't know how the cost of that stacks up against the added complexity of a delay module and all that.
So for simplicity, I think it's worth a try to just switch the transformer along with the pump. Worst case it trips the breaker and you'll need to rethink your setup then. But I would absolutely try to get the transformer's supply voltage as high as possible by putting it at the switch and not at the well head.
Whitenuckler
Minister of Fire
The cable for the pump was sized based on 230v. If you start to use it at 115V the current will double.
I myself would take the 230V cable off the panel and put it in a box with the proper male receptacle. The add a
new cable into the panel with the matching female plug. Now you have normal, the way it is now. Then grab a 15A feed
from your emergency panel and put hook it to the transformer 115V side (perhaps with a fuse). Then wire a cable
from the transformer 230V side (perhaps with two fuses) to a female plug. I'd rather only be using the emergency system
when it's required.
I myself would take the 230V cable off the panel and put it in a box with the proper male receptacle. The add a
new cable into the panel with the matching female plug. Now you have normal, the way it is now. Then grab a 15A feed
from your emergency panel and put hook it to the transformer 115V side (perhaps with a fuse). Then wire a cable
from the transformer 230V side (perhaps with two fuses) to a female plug. I'd rather only be using the emergency system
when it's required.
That certainty relieves safety concerns (since transformer only energized during outages). I have no idea if transformers are actually safety hazards anyhow; I guess if they severely overheat, but I'll know pretty soon if that's likely, shouldn't be since I'll be running it well below its rated VA).
Whitenuckler
Minister of Fire
Transformers are fused with fuses matched to the rating. That's more of the industrial design and code ect. They can fail and the protection needs to isolate it. The load side is more to protect the load cable/load. The supply side would be to protect the transformer. A 15a breaker will provide only protection for the supply wires. You can order single and double fuse holders/fuses. For home use/design I'd just use a 15A breaker to turn it on and off, and a fuse mounted near it on the supply.
A transformer idling with no load is not really a hazard any more than any other live circuit would be. Loaded heavily they can start to generate some heat but as long as it's not buried under a stack of newspapers you're probably fine.
The fusing on the primary needs to be either time delay or sized to account for the transformer inrush or they will pop every time you power it up. I would think a 20A breaker would be adequate protection for your transformer.
The fusing on the primary needs to be either time delay or sized to account for the transformer inrush or they will pop every time you power it up. I would think a 20A breaker would be adequate protection for your transformer.
Not running the pump through the transformer during normal conditions would also address the issue of if it's somehow not good for the pump to run it that way; but I can't really imagine what that'd be, as long as it's getting sufficient voltage/current, which it should be with this 2000VA transformer.
I'm imagining something like this ...
![[Hearth.com] power flickering from small 12vdc -> 120vac inverter attached to EV](https://www.hearth.com/talk/attachments/screenshot-2026-03-14-at-5-37-02%E2%80%AFpm-webp.346995/ "[Hearth.com] power flickering from small 12vdc -> 120vac inverter attached to EV")
... so no plugs or receptacles at all. The three cables enter the box through cable clamps.
Seems like a lot of trouble when I could just buy or build a 240vac power station, but that's WAY more expensive.
I'm imagining something like this ...
... so no plugs or receptacles at all. The three cables enter the box through cable clamps.
Seems like a lot of trouble when I could just buy or build a 240vac power station, but that's WAY more expensive.
... And kill the circuit to the transformer unless you're running on backup power.
Seems like a solid plan to me. Yes, it's more complex but oftentimes I find that is the case -- off the shelf solutions are more expensive than what you can do with a bit of DIY engineering.
Whitenuckler
Minister of Fire
Can you show how the inverter gets connected? You have an emergency tie in that is 115V or 230V?
What was the pump rating? You may not need the full 2000KVA capacity. 1HP?
I have a 30amp generator inlet (L14-30) feeding into a 30amp double-pole breaker in my main panel. It is interlocked with the main breaker using an OEM interlock that protects even when the dead-front is removed. This is legal in my jurisdiction.
Right now I'm feeding it from a 12v->120vac inverter that connects to the 12v system in our Nissan Leaf EV. So I tied both hots of the L14-30 plug to the hot on the 5-15 plug that plugs into the inverter. This is acceptable only because my house has no multi-wire branch circuits (MWBC) with two hots ordinarily out of phase with each other sharing a neutral. It means all 240vac loads see zero volts, which is fine because that inverter can't handle 'em (except maybe the well pump). I intend to connect whatever 120vac power station I buy (or possibly DIY build) in the same fashion.
Here is a screenshot of the electrical specs of the pump ...
Note the power factor is 1.00. Like I said, I've measured 5 amps consumption (with no discernible startup surge), probably because the head is only 100ft, half the pump's rating. It's interesting that the sticker that came with the pump to put on the well-head says 6.4 amps; is it or the 8.4 amps in the specs a typo ?!? So yes, maybe I should could get by with a smaller transformer, but it seemed silly to skimp, since that's one way to damage the pump motor. But if I'm only running it during grid outages, I suppose I needn't be so worried. But honestly, this Acme one (pictured in post #27) seems like a really good deal, and I like the fact I found documentation on it explicitly sanctioning reverse feed (120vac -> 240VAC).
Last edited:
Whitenuckler
Minister of Fire
That transformer must weigh 40 pounds? Lots of laminated steel and copper. Might cost $80 to ship on a truck.
It's gonna go between the xformer and the cable leading to the pump, no ? Doesn't it need to be double-pole and 10 amps or so contact rating ?
