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Old 10-19-2012, 09:55 PM   #1
ftlstrings
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Mar 2008
Kirksville, Missouri
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Hey all, can I safely use a spst 120v switch on one leg of my 240v march pump to switch on/off? I've seen people post both yes and no in various spots and don't want to, um, die.
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Old 10-19-2012, 09:58 PM   #2
Balanced_Brew
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Jun 2012
Portland, OR
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Haven't done exactly what you're doing, but yes - you will get ~120V from one leg of your 240 to Neutral.
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Old 10-20-2012, 12:15 AM   #3
jasonsbeer
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Jul 2009
Central Iowa
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Yes, you can. All the 120v items in my brew panel pulls from one leg on the 220 feed.

Just be sure it's properly sized for the circuit.
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Old 10-20-2012, 12:30 AM   #4
P-J
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Mar 2010
Charlotte, NC
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Quote:
switch on one leg of my 240v march pump to switch on/off
Wait... Wait...
Is your pump a 240V model?

If that is what you have, you need to use a DPST switch to control it.

 
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Old 10-20-2012, 05:57 AM   #5
ftlstrings
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Mar 2008
Kirksville, Missouri
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Mine is the 240v model. It does nothing when hooked up to 120.
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Old 10-20-2012, 06:01 AM   #6
ftlstrings
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Mar 2008
Kirksville, Missouri
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Let me say this too: I had two electrical guys, one an electrical engineer, looking at this when we designed it on a rolling stand, and they set it up with one leg being switched. This worked for years. Now I'm looking to hard wire something into my house for a brewery and I wanna make sure it's safe for the fam, and during brew day.
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Old 10-20-2012, 11:56 AM   #7
OMJ
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May 2009
Camp Hill, PA
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I'm with PJ on 240 switch both legs.

 
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Old 10-20-2012, 12:10 PM   #8
grandequeso
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Aug 2012
jacksonville, fl
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It is not uncommon to switch one leg of a 240v pump to control it on & off. If the swicth is going to function as a disconnecting means for the pump then you want it to break both legs of power. That being said if your control box that feed the pump has a main power switch or is cord and plug connected you could just as well call that your main disconnecting means.

 
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Old 10-20-2012, 01:22 PM   #9
porcupine73
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Aug 2012
Fort Meade
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Will it work to switch only one leg/phase? Absolutely. You just have to bear in mind that even when it isn't running the pump is still hot. Would you be working inside the control panel hot anyway? Probably or hopefully not. Is it a better practice to switch all ungrounded (non-neutral) conductors? Yes it is.

 
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Old 10-20-2012, 03:55 PM   #10
jasonsbeer
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Jul 2009
Central Iowa
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Depending on the kind of switch your looking at, the price difference between a SPST and DPST is negligible. Just shop smart.
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