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


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#6696 - 01/09/02 11:36 PM Re: Reversed Polarity  
amp-man  Offline
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Joined: Jun 2001
Posts: 141
Sacto, California US of A
Tom,

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?

Cliff


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


#6698 - 01/10/02 12:01 AM Re: Reversed Polarity  
Nick  Offline
Member
Joined: Aug 2001
Posts: 599
Riverside, CA
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.


#6699 - 01/10/02 12:17 AM Re: Reversed Polarity  
aldav53  Offline
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Joined: Aug 2001
Posts: 545
Chandler, AZ USA
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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#6700 - 01/10/02 08:20 AM Re: Reversed Polarity  
electure  Offline


Member
Joined: Dec 2000
Posts: 4,259
Fullerton, CA USA
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]


#6701 - 01/10/02 08:39 AM Re: Reversed Polarity  
Redsy  Offline
Member
Joined: Mar 2001
Posts: 2,056
Bucks County PA
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.


#6702 - 01/12/02 10:36 AM Re: Reversed Polarity  
Tom Post  Offline
Member
Joined: Sep 2001
Posts: 7
Philly
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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