Re: simple electrical question

Jul 23, 2003 3 Replies


hello all, i'm sorry to post this question on this ng but i don't have


> access to electrical ngs.
> my question goes like this:
> when using a clamp meter to measure current value for a single phase cable
> (the cable containing live , neutral and earth wires). when i clamp the 3
> wires (live, neutral and earth) , i don't get any results. but when i clamp
> only the live and neutral, i get the current value.
> my question is : is the earth wire preventing the reading of the current
> value? if so why??
> thx
> Hasta Luego

Your clamp on meter is reading the net current in your cable bundle. I would hope that all the current going "out" your line is returning via your neutral. ;-) Using a clamp on meter on the individual lines is the correct procedure. BTW, the earth lead should be carrying no current for properly designed equipment.

You have a fault condition. Clamping Live, Neutral and Ground should, as you've reported, read zero. Clamping Live and Neutral but not Ground _SHOULD_ read zero. Clamping either the Live alone or Neutral alone should give you the load current. If you read ANY current in the Ground lead, (clamping it alone of course), then you have a serious malfunction (reversed ground/neutral) that could be a fire hazard or shock hazard.

GET IT FIXED NOW!

Good Luck Rich

What he said, in spades

Brian W

what you both said in double spades with the operative phrase being "get it fixed", not "fix it", since anyone asking this question shouldn't even be messing with this stuff in the first place.

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