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Senior Advisor

230V And Dedicated Neutral?

It seems that newer 230V single phase motors take 2 hots, a ground and a dedicated neutral.  If the wire goes back to the main box and is not a shared circuit, why is a dedicated neutral needed?  Why can't one simply parallel off the ground?  In the main box, the neutral and ground may connect to the same lug.  Why not at the other end?

I"m not talking about coming off a sub panel.

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4 Replies
Contributor

Re: 230V And Dedicated Neutral?

Safety.  What if the existing neutral wire or connection goes bad and you lean against the motor and the motor happens to have short in it and you become the new better connected ground.  I would rather have the extra wire become the better ground and not worry about hoping my body has a higher impedance at that instancde that the faulty neutral wire.  Tons of the older ones are wired with just the neutral wire hooked up without a safety ground, but for the small cost I would sure hook up the extra neutral/ground wire.  Actually a 230 v motor runs off of the voltage difference between the phases and will work without any ground, however it is a really bad idea in the long run.  Also if you ever hook the circuit up to a GFCI hooking the neutral and safety ground together also can cause the GFCI not to function properly, thus losing the safety protection.

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Senior Advisor

Re: 230V And Dedicated Neutral?

Thanks.  I suppose it is supported by history or some likelihood.  I have a 2 wire plus ground cable buried so adding a dedicated neutral is not real simple.  I might ground the case with a ground rod.  Would be better than nothing. I have another unused wire that is buried that maybe I can piggyback on, but it will involve some jerry rigging. 

 

The installation is on a fan on a bin.  I've always put a grounding rod on the bins for whatever reason I don't know.  The box is grounded, as well.  I know there can be a voltage drop between two ground rods.  

 

Well, I appreciate the response.  I'll have to see what I can do.

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Contributor

Re: 230V And Dedicated Neutral?

Most of the older ones are wired with one neutral wire, so I would not worry about it much.   It is a good idea to always ground the bins, helps in the possible electrical short situation, and also helps keep a lightning strike under control.   I use 3 gound rods just for the bin on our taller 24 ring bins.  Shorter ones are less likely to get hit and usually just have one ground rod.  

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Senior Contributor

Re: 230V And Dedicated Neutral?

It will work but you really want your 110 volt items you hook up on the bin to have hot, neutral, and dedicated ground.
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