Does The Neutral Have A Voltage? - Electrical - DIY Chatroom Home Improvement Forum

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Old 03-11-2007, 06:30 PM   #1
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does the neutral have a voltage?

Lets supposed that we have a 3 phase Wye transformer 208/120V and one of the phases is out of valance with the neutral by lets say 20 Amps, something like phase 1 has a 100 amps load, phase 2 also 100 amps but phase 3 only 80 amps, in such case I been told the neutral will carry the 20 amps difference. Would I get zapped by the neutral under such or any other circumstances?


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Old 03-11-2007, 07:38 PM   #2
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The neutral is typically "earthed" or connected to earth ground at the source. That being said, its ideal or theoretical voltage is 0 volts w.r.t. ground (i.e. your potential, typically). So, in theory, you should be able to touch it and not receive a shock. In the real world though, we know that given the finite resistance of the cabling, the voltage on the neutral will rise from 0 V at the earthing point (the transformer in your case) to some non-zero value at the load assuming that some current is flowing. As the current and length of cable increases so will the voltage rise measured to earth. What the measured voltage will be depends on a host of factors but why risk electrocution? Use the proper PPE and keep your (uninsulated hands off).


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Old 03-11-2007, 08:03 PM   #3
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It is unlikely the connected neutral will be carrying any noticeable voltage measured to ground, but it is most certainly carrying current in the state you describe.

I MUST say. Even though this is a "what if" question, 3-phase (ESPECIALLY 277/480) is NO place for anyone untrained to be messing around.
I truly hope this IS a "what if" question.
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
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Old 03-12-2007, 05:05 PM   #4
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thanks a lot for the answers!!! I work with lots of 3 ph equipment and Iím always trying to learn more about the electrical side of it.
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