CT's ok on Neutral Wires?

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wci68
Posts: 43
Joined: Thu Dec 17, 2015 4:31 pm

Re: CT's ok on Neutral Wires?

Post by wci68 » Tue Nov 22, 2016 7:33 pm

johnstonf wrote:Am I not allowed to ask why?
Knowledge is not a bad thing, is it?
No it is not, though as already noted above this may be best to discuss with your electrician.

The short answer is that on a 240V load, such as a clothes dryer or electric range, the neutral only carries the difference between the two lines. In some cases there may not be a neutral at all on 240V loads.

The long answer becomes a bit more technical, and is related to the same reason that if you use a single CT to monitor two loads on two different legs (not really "phases") the wires for those loads need to pass through the CT in opposite directions.

As for using neutrals over hots for monitoring loads, as also already noted it can be done but on 240V loads it will not be accurate (see reason just above).

From your comments I'm guessing you are thinking of using neutrals simply because they may be close together in your panel but this really isn't a reason to use the neutrals. The priority should be first in choosing which loads you want to combine for one measurement by one CT. Your electrician can very easily make that work using the hots regardless of whether or not they are physically "close" in your panel. Again - that would be a discussion to have with your electrician.
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