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Electrical Wiring

mains disconnect wiring question

15 years ago

I am installing a 100A meter socket with associated 100A load center. Between them I am installing a disconnect switch. This is a DU323RB from square D. It is a 100A knife switch/3 pole. The service is 120/240v three wire. My question is, do I only connect the hot legs to the switch and carry the neutral through to the load center? Or is the neutral switched as well? I have not found any information regarding this. This is not a residential issue, it is related to power for grain bins. thanks.

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Comments (7)

petey_racer
15 years ago
Oh boy. Farmer electricians.

Sorry, some of the worst and most dangerous installations I have ever seen were on farms, done by folks who knew just enough to make it work, yet still be extremely dangerous.

NO, do NOT switch the neutral. Only switch the hot legs.

WHY did you get a 3-pole disconnect? Don't tell me, it's used and you got it for free.
pharkus
15 years ago
At least he came in here and ASKED instead of just doing it wrong.

Most of the bad/dangerous installations end up getting done by people who refuse to ask anyone or accept anyone's input.
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petey_racer
15 years ago
Oh, I do agree with you. I guess that was partly my point that I never made.
bob_the_farmer
Original Author
15 years ago
Hi guys, my profession is not farming, my wife and I inherited some land. I work with electronics, but I am not an electrician. I know the devil is in the details, that is why I ask you experts. So, if the neutral is to be carried through, do I need a neutral bar to connect through, or can the wire simply go in/out of the disconnect box to the load center? details,details...

thanks
petey_racer
15 years ago
If there is no reason for the neutral to be terminated, such as your application, it can pass right through the enclosure.
Obviously the switch must be grounded though.
pharkus
15 years ago
bob_the_farmer, similar here - I've been wearing my "electrician" hat quite a bit lately, but electronics would be my home field.

Welcome to the world of career crossover. Today I also got to play carpenter. I hate pretending to be a plumber. :P

General idea in all of this is that ground and neutral never get broken anywhere. If you turn off every switch in an entire building, all of the neutral wires will still be connected to each other, and same with the grounds. Only switch hots - ever. Actually I try to carry that over into electronics as well. :)
bob_the_farmer
Original Author
15 years ago
I appreciate all of the information. I only want a safe installation. I too have seen strange stuff. I am trying to get it right and freely admit I do not know everything. That is why there are forums like this, to fill the gaps in our knowledge. Believe it or not, there are even things I know that others do not. ;)

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