Step-down Transformer?

Our source of domestic water is a spring. There is a pump enclosed in a pump house and it operates on 220V. I want to install a filter system that uses a clock (110V) to control backflushing of the limestone filter. My problem is, the power to the pumphouse consists of two hots and a ground, no neutral. What I want to know is, can I use one of those step down transformers to get 110V to operate the clock? As near as I can determine from websites describing the transformers, they are made to be used with 220V european (or elsewhere in the world) power. Those voltages are a single hot with respect to ground while US 220V is what it is, with each hot at 220V with respect to the other hot. Can I use one of these transformers with US 220V input? I can't see much of any other option rather than replacing the wiring to the pumphouse which would be beaucoup expensive (underground wiring) given the distance. Any help is appreciated.
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(Blackdogs) wrote:

Is there some reason that the filter has to be in the pumphouse? Presumably you have 110V available inside your house; why not put the filter there?
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Blackdogs wrote:

Hi, You may have 110 volts acros one leg of hot and ground. If so tap it from there. Tony
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On Sat, 16 Oct 2004 12:47:03 -0700, Tony Hwang wrote

Blackdogs -
I emphatically disagree with Mr. Hwang's suggestion. You should never use the equipment ground as a neutral return path. It will certainly "work", but you have potential touch voltage on the entire ground path (equipment housings, conduit, etc.) back to the panel. If that path gets interrupted anywhere by a break or high-resistance connection, you will have a very hazardous situation. Using the ground in this way is, of course, a code violation and with good reason.
I am not familiar with the European to US transformers, perhaps another poster can tell you if they're suitable.
However, you certainly can get a small hard-wired 220V to 110V step down transformer for your application, but it's not a Home Depot item. This sort of "separately derived system" is done all the time in industrial/commercial installations. You end up with a transformer feeding a small panel with a breaker for the 110V circuit. One of the transformer secondary terminals is grounded in the panel and you have a "normal" 110V to neutral branch circuit. It's not hard to do, but the details (particularly concerning grounding) are a little hard to understand. Depending on how ambitious you are, it may be better to have an electrician do this.
Whatever you do, please don't use the ground as a neutral.
- Kenneth
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but
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Yup, ditto what you said on using the ground.
Plenty of control transformers around cheap enough, suggest an electric motor shop--these are often salvaged from scrapped wood and metalworking machinery, or perhaps try Ebay.........
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&categoryB891&item845630930&rd=1
Ground one tap of the 110v ( secondary ) side to your existing ground, and use that also as your neutral--the other secondary tap becomes your hot leg.
--

SVL





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KJS wrote:

Hi, In this case it's only a clock. It can float. Enclose in a plastic enclosure or something. Won't even draw much current. Tony
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If you connect one side to the ground, it's not floating.

Has _nothing_ to do with the clock, other than it's providing a continuous current flow thru the ground.
If that ground ever gets interrupted, then _everything_ that's grounded in the shed (including the pump housing) goes live.
Double plus ungood.
--
Chris Lewis, Una confibula non set est
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snipped-for-privacy@directcon.net (Blackdogs) wrote:

http://www.allelectronics.com
about 20 different models of voltage converting transformers. Various sizes, and prices.TC-100,TC-300,TC-500,TC-2000,TC-1300 etc, starting at $20.
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There are clocks that work on 220-240 volts. I have used them a lot on swimming pools.
Back feeding the European transformer will limit the amount of current available. IE 220 in and 120 out. They are not made to work that way. Also a lot of European 220 is 50 hz which will not work with a clock motor looking for 60hz. Call the filter manufacture and ask for an 220 volt model. Or an conversion for the one you have.
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The frequency is not an issue. Apparently he has a clock motor, where the only problem is it needs 110, rather than the 220V which is available to run it. Any transformer that works at 50hz will work at 60hz for this application. Whatever frequency he puts in, that is what will come out.
Nor should current be an issue, since he's only running a clock. That's exactly the small kind of load these international converters are intended to run.

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snipped-for-privacy@directcon.net (Blackdogs) wrote in message

The short answer is yes, the transformer has two wires coming in with 220 and 2 going out with 110, so physically it will work. As to whether you can hook it up to be safe and pass code, that is another question that I don't know the answer to, ie what kind of outlet, plug, is it allowed to hook the particular clock device in via a plug, etc.
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On 16 Oct 2004 17:25:18 -0700, snipped-for-privacy@optonline.net (Chet Hayes) wrote:

I definitely will not pass code and can present a hazard in the way a previous poster pointed out.
Dan
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timers are avail 220v. if it has a standard old time clock motor, changing it out to a 220v clock motor is pretty darn simple

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Blackdogs writes:

Don't do that unless you know the difference between a transformer and an autotransformer and why it matters. Many foreign-voltage conversion "transformers" are actually autotransformers.
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