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-   -   240v switch on one leg? (http://www.homebrewtalk.com/f170/240v-switch-one-leg-362244/)

ftlstrings 10-19-2012 09:55 PM

240v switch on one leg?
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.

Balanced_Brew 10-19-2012 09:58 PM

Haven't done exactly what you're doing, but yes - you will get ~120V from one leg of your 240 to Neutral.

jasonsbeer 10-20-2012 12:15 AM

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.

P-J 10-20-2012 12:30 AM


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.

ftlstrings 10-20-2012 05:57 AM

Mine is the 240v model. It does nothing when hooked up to 120.

ftlstrings 10-20-2012 06:01 AM

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.

OMJ 10-20-2012 11:56 AM

I'm with PJ on 240 switch both legs.

grandequeso 10-20-2012 12:10 PM

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.

porcupine73 10-20-2012 01:22 PM

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.

jasonsbeer 10-20-2012 03:55 PM

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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