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Reversed Polarity #6695 01/09/02 11:26 PM
Joined: Sep 2001
Posts: 7
Tom Post Offline OP
What is the true concern over reversed polarity?

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Re: Reversed Polarity #6696 01/09/02 11:36 PM
Joined: Jun 2001
Posts: 141
amp-man Offline

First, let me ask you a question: What should I do when I run out of left-handed switch boxes? (You know, the ones that go on the left side of the stud).

The point is, what is the context of your question on polarity? Are you talking about telephone wiring?


Re: Reversed Polarity #6697 01/09/02 11:36 PM
In regards to...........?

Re: Reversed Polarity #6698 01/10/02 12:01 AM
Joined: Aug 2001
Posts: 599
Nick Offline
Let me give you one example. 120V branch circuit feeding a standard portable lamp in your home. The plug on the lamp is polarized IE; has one prong larger than the other so it can only go in the receptacle one way. If the polarity on the receptacle is reversed the screw shell of the lamp will be at 120V potential when the lamp is turned off. Very dangerous.

Re: Reversed Polarity #6699 01/10/02 12:17 AM
Joined: Aug 2001
Posts: 545
aldav53 Offline
On some of the old metal drills, old TV chassis etc., the casing or chassis could have a potential of becoming hot I believe.

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Re: Reversed Polarity #6700 01/10/02 08:20 AM
Joined: Dec 2000
Posts: 4,283
electure Offline
If you're asking about neutral and hot conductors being reversed consider:
Hard wired garbage disposal, neutral is switched, leaving continuous hot to G/D at all times. Plumber goes to change it out. He shuts off switch and thinks all's well. As he removes wiring from under sink, he encounters hot wire while laying across the grounded plumbing=dead plumber. [Linked Image]

Re: Reversed Polarity #6701 01/10/02 08:39 AM
Joined: Mar 2001
Posts: 2,056
Redsy Offline
The screw shell on a lampholder is required to be connected to the grounded circuit conductor only. You are much more likely to contact this portion of the fixture while changing a bulb. If it is an outdoor porch light and you are barefoot... goodbye.
Also, as in the GD example above, an inadvertant ground fault inside the motor may turn the unit on without the switch being closed.

Re: Reversed Polarity #6702 01/12/02 10:36 AM
Joined: Sep 2001
Posts: 7
Tom Post Offline OP
Thanks all. I am/was referring to reversed polarity at the receptacles.
If I am understanding most of you than the main concern is that the item that is plugged into the receptacle may become energized on the conductive exterior of the unit. Is this correct?
As for the Plumber that is working on the D/W, I agree but shame on him for not shutting off the breaker prior to working on the unit.


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