Re: Switching off ONLY one pole on a 220V pump
- From: N8N <njnagel@xxxxxxxxxxx>
- Date: Thu, 31 Jan 2008 09:22:37 -0800 (PST)
No, the current is the same through both legs, it doesn't matter in
that regard whether you switch one or both. But you do want to switch
both off if you ever need to service anything as if only one leg is
switched off, the other will be live with respect to ground, therefore
possible hazard.
nate
On Jan 31, 7:19 am, "RBM" <r...@xxxxxxxxxxx> wrote:
For safety, you want a disconnect to kill both legs of the feed. For the
operation of the pump, using both poles of the pressure switch pulls less
current per pole, so the switch will last longer. Depending upon the HP of
the pump and switch, this may not be that important. You can also install
jumpers in the pressure switch so the two poles work together to close the
one circuit.
<letter...@xxxxxxxxxxx> wrote in messagenews:fnscj7$atn$1@xxxxxxxxxxx
I have a 220V submercible well pump. I am not going to even try to
describe the location of the control box, pressure switch, etc. It's
an odd situation because the pressure tank is in an underground
concrete pit and the control box is in my garage, with the well
outside in another location.
Anyhow, because the wires were embedded into the conrete of the pit,
and only used a 2 wire UF cable, I can only switch one side of the
220. Otherwise I'd have to do some major digging and concrete removal
underground. The control box is wired correctly to the pump. It's
just that the pressure switch only switches one side (pole) of the
220.
This has been this way for years, and works fine. However, I just had
my tank rupture and although I worked as a plumber for years before I
retired, I could not get into this pit with the cover frozen shut. I
finally called a plumber, who had to contact another guy to remove the
frozen soil. When we opened the pit, it was nearly filled with water,
and the electrical connections were under water. That lead to him
bringing a pump to pump the pit dry.
Anyhow, the weather has been so severe that I just let him finish the
job, after buying the tank and a new pressure switch myself. (I just
dont function well in severe cold anymore). He did a good job, the
cost was not as bad as I thought it might be, and I have water again.
However, the plumber told me that I should really be switching off
BOTH poles of the 220 on the pressure switch. I honestly can not see
why. On a light switch you only shut off one of the two wires......
Why should it matter whether it's 110 or 220? It's still the same
circuit.
One thought I do have to solve this is to apply a low voltage to those
two wires, and use the low voltage to flip a heavy duty double pole
relay inside the garage. That would switch both poles of the 220, yet
not require any digging. Another advantage, if the pit filled with
water again, I would not have live 220 voltage under water. (It still
amazes me the breaker never blew, the pump just would not run while
those wires were submerged).
I guess this would be the solution and would not be that hard to wire,
but is it really necessary?
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