# From



## Majestic (Jul 18, 2016)

I am changing a machine from 460V to 240V. I have rewired motor to 240V and Changed Contactor for the increased Voltage from an Allen Bradley 100-c-16 10 to 100-c30 00 C.I changed the thermal to 23 amp from 12.the old Coil was 460V but the new one is 120V Can I pick up 1 leg not the wild leg to coil and the other side of the coil to neutral. Does this sound correct and is there anything I am missing. any help appreciated.


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## telsa (May 22, 2015)

That's a new one on me. I've only ever seen fellows go the other way.

Why?


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## Majestic (Jul 18, 2016)

machine came out of a shop with 460v we have 240v


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## backstay (Feb 3, 2011)

As long as you have a neutral, controls can be 120 volts.


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## Wirenuting (Sep 12, 2010)

So let me get this strait, 
You have a 480 3 phase machine and want to run it on 240 single phase?
Is this a compressor in your garage?


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## Majestic (Jul 18, 2016)

no 3 phase 240 volt


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## Cow (Jan 16, 2008)

Majestic said:


> no 3 phase 240 volt


Where are you going to get a neutral then for your 120v controls?


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## telsa (May 22, 2015)

Cow said:


> Where are you going to get a neutral then for your 120v controls?


At 240 3-phase we can assume that he's got a center-tapped delta Service.

Then, no problem.


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## Majestic (Jul 18, 2016)

any neutral will work won't it.


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## Flyingsod (Jul 11, 2013)

Check for any little control transformers and wire them for the new voltage. Control panel lights as well. Check for any relays in the control circuits. 
I second the comment that using 120v for the controls is fine in theory. Just be sure to check the entire control circuit for components that might be expecting a different voltage. GL


Sent from my C6725 using Tapatalk


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## philipdybel (Feb 29, 2016)

*240 Volt Coil*



Majestic said:


> Can I pick up 1 leg not the wild leg to coil and the other side of the coil to neutral.


Yes. However the neutral "should" belong to that same circuit (and not some random neutral you found in the control box, from another circuit).

Because usually a 3-phase motor circuit is 3 wires "only", with no neutral.

Options:
1) Run a neutral for the 3-phase circuit, fuse down one of the phase conductors for your control wiring (make sure it isn't the wild leg)
2) Run a separate 120-volt control circuit
3) Use a 120-volt control transformer, fuse primary as needed
4) Swap out the contactor coil with a 240VAC coil:








See "Bulletin 100-C Replacement Coils" at http://www.ab.com/en/epub/catalogs/12768/229240/229254/229461/229481/Renewal-Parts.html


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## Cow (Jan 16, 2008)

telsa said:


> At 240 3-phase we can assume that he's got a center-tapped delta Service.
> 
> Then, no problem.


You make a lot of assumptions, I've noticed.

He said he had 240 3 phase available, he did not say he had 240 3 phase with a neutral available at the machine he's rewiring. You can't know where the circuit originates and and just how much of a "no problem" it is to get a neutral to this machine.


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## backstay (Feb 3, 2011)

We're all assuming, because he never gave us enough information.


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## Majestic (Jul 18, 2016)

I do have a neutral at the machine.


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## philipdybel (Feb 29, 2016)

*All Neutrals Are Equally White (Or Gray)*



Majestic said:


> any neutral will work won't it.





Majestic said:


> I do have a neutral at the machine.


In Soviet Russia we use any neutral with any hot wire, we do not discriminate...

So I ask: why couldn't you just use "any neutral" for this? Basic NEC code / safety standards? Other electricians seeing it & commenting on it? Getting blamed for "doing it wrong" when something else goes bad in the future?


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## Bird dog (Oct 27, 2015)

philipdybel said:


> So I ask: why couldn't you just use "any neutral" for this? Basic NEC code / safety standards? Other electricians seeing it & commenting on it? Getting blamed for "doing it wrong" when something else goes bad in the future?


All of the above. Violates basic circuit design. We don't want to start fires and shock/electricute people.


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## philipdybel (Feb 29, 2016)

*Ding Ding Ding - Correct Answer*



Bird dog said:


> All of the above. Violates basic circuit design. We don't want to start fires and shock/electricute people.


Thanks bird, you've answered my "rhetorical" question perfectly.

/thread


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## JRaef (Mar 23, 2009)

The safe bet, since you don't KNOW if there is a neutral or even if there is, it was not brought out to the machine, is to use a basic Control Power Transformer to go from 240-120V. If you can't fit that, change the coils again to 240V and go Line to Line.


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## MechanicalDVR (Dec 29, 2007)

JRaef said:


> The safe bet, since you don't KNOW if there is a neutral or even if there is, it was not brought out to the machine, is to use a basic Control Power Transformer to go from 240-120V. If you can't fit that, change the coils again to 240V and go Line to Line.


Exactly the most expedient way of going forward.


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