Multimeter Circuit Breaker Neutral Questions

ardmiOctober 29, 2013

Need refreshing on how to test a breaker with a multimeter....

Black (Com) can go to any screw on the neutral bar right? (dont have to use the same neutral that travels in conduit with hot wire).

Then red onto screw on breaker to test 120.

And for a 240 breaker it would be both leads on each screw of breaker to test 240. Then red on one screw and black on ANY screw on neutral bar for 120 (repeat).

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Ron Natalie

Yes, actually it doesn't matter which color lead of the meter you use where. All the terminals on the neutral bar should be at the same potential.

    Bookmark   October 29, 2013 at 11:18AM
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I know these are basic questions I should know, so thanks for clarifying. I was always confused if I had to test hot to neutral on wires sharing the same raceway.

How about testing from hot to ground with a breaker? Or is that what I am doing by testing on any screw of the neutral busbar? Or would I test from the hot to the side of the metal enclosure in that case?

YOur propbably thinking I shouldnt be sticking things in breaker boxes if I have to ask these questions!

    Bookmark   October 29, 2013 at 7:39PM
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Some multimeters have built-in protection against damage from being used on the wrong function or range. But some will be instantly ruined if set for resistance (ohms) and then the test leads are placed across 120 volts.
To test for the presence or absence of power, much simpler, lower cost, and more foolproof testers are available.
Exactly what test results are you seeking and why?

    Bookmark   October 30, 2013 at 7:11AM
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Ron Natalie

The other thing is to not be fooled by open circuits. The digital meters are usually of sufficiently high impedance that they'll read something on a long unterminated wire.

    Bookmark   October 30, 2013 at 7:17AM
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Thanks Busdriver, I was just testing to to assure I am getting proper voltage at breakers.

I picked up a new multimeter the other day and wanted to put it thru the tests. In fact as Ron mentioned, it has a low impendance function to avoid phantom voltage readings. It can read both voltage AC/DC and continuity at the same time. The function is not for testing of electronics though.

    Bookmark   October 30, 2013 at 7:44AM
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