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Old 09-11-2008, 07:58 AM
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Jerry Peck Jerry Peck is offline
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Re: Voltage on grounding cable
Quote:
Originally Posted by Brian Robertson View Post
I will try the appliance shutoff thing. Now would I just need to shut them off or unplug as well?

Brian,

In most cases, just shut turn them off (if there is a bad neutral/neutral connection problem). In this case, no need to address 240 volt appliances, they do not cause problems when there is a bad neutral.

However, if you are looking for ground faults, disconnect/unplug them. In this case, you can have ground faults in 240 volt appliances.

Here are two examples of bad neutrals: 1) neutral conductor making poor connection in neutral terminal causing high resistance - usually you can see evidence of this at the terminal or in the insulation of that neutral near that terminal; 2) overhead service neutral/hot leaking through to each other, causing the conductor to corrode, causing higher resistance.

If you increase the resistance in the neutral conductor, it become closer to the resistance of the earth ground back to the transformer. If the neutral conductor resistance increases enough (so the resistance of both paths are the same) the same amount of current will flow through the ground path as through the neutral path.

Increase the resistance of the neutral conductor to its maximum (cut it) and all of the neutral current will through the ground conductor, but that creates its own problems because it is now a higher resistance path back to the transformer, among other problems. Which is why it is "not intended to" have current on it.
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