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Polarity testing #90682
12/08/04 01:16 AM
12/08/04 01:16 AM
T
tdhorne  Offline OP
Member
Joined: Mar 2001
Posts: 345
Maryland, USA
When your plug in tester reads polarity reversal and your wiggy reads 120 volts from ground to neutral and from hot to neutral what two totally different failures can cause this.
--
Tom

[This message has been edited by tdhorne (edited 12-08-2004).]


Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
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Re: Polarity testing #90683
12/08/04 01:29 AM
12/08/04 01:29 AM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,347
Estero,Fl,usa
Open neutral upstream and that may be a bad contact in a GFCI receptacle (covered here several times). You are seeing a back circuit through the downstream load.


Greg Fretwell
Re: Polarity testing #90684
12/08/04 11:46 AM
12/08/04 11:46 AM
J
John M Caloggero  Offline
Junior Member
Joined: Nov 2004
Posts: 7
Virginia Beach VA
I assume you are taking measurements at the receptacle. The tester is saying you have reversed polarity, that means the neutral and live conductor are reversed. It sounds like the grounded conductor (neutral) is connected to the brass colored terminal to which the live conductor is supposed to be connected, and the live conductor is connected to the white or silver colored terminal to which the grounded conductor (neutral) is to be connected.

Re: Polarity testing #90685
12/08/04 04:32 PM
12/08/04 04:32 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,347
Estero,Fl,usa
John if this is a simple polarity reversal you wouldn't see volts on the brass screw


Greg Fretwell
Re: Polarity testing #90686
12/08/04 04:51 PM
12/08/04 04:51 PM
N
n1ist  Offline
Member
Joined: Feb 2002
Posts: 183
Malden MA
If you reverse hot and neutral you would see this. If you roll all 3 lines so hot is on silver, ground is on brass, and neutral is on green, you would also see this.
/mike

Re: Polarity testing #90687
12/10/04 09:45 PM
12/10/04 09:45 PM
B
BigB  Offline
Member
Joined: Mar 2004
Posts: 742
Tucson, AZ USA
It's an open neutral, nothing else. Most of the cheap plug in testers will show reverse polarity on an open neutral condition since the neutral is now at 120V potential from upstream load.

Re: Polarity testing #90688
12/10/04 09:51 PM
12/10/04 09:51 PM
B
BigB  Offline
Member
Joined: Mar 2004
Posts: 742
Tucson, AZ USA
Sorry I didn't notice you said 120 from hot to neutral. It must be like mike said,simply reverse polarity. Your getting 120 from neutral to grd because your neutral is really a hot.

Re: Polarity testing #90689
12/11/04 01:08 AM
12/11/04 01:08 AM
T
tdhorne  Offline OP
Member
Joined: Mar 2001
Posts: 345
Maryland, USA
How I got the readings described were from a fault from the hot to the Equipment Grounding Conductor with an open in the EGC between the fault and the source.
--
Tom H


Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
Re: Polarity testing #90690
12/11/04 07:52 PM
12/11/04 07:52 PM
B
BigB  Offline
Member
Joined: Mar 2004
Posts: 742
Tucson, AZ USA
Tom, did and earlier fault cause the EGC to blow apart, then become energized when the breaker was reset?
Just goes to show how trying to guess a problem without being there can make a fool out of you.

Re: Polarity testing #90691
12/12/04 11:01 PM
12/12/04 11:01 PM
T
tdhorne  Offline OP
Member
Joined: Mar 2001
Posts: 345
Maryland, USA
Quote
BigB Tom, did and earlier fault cause the EGC to blow apart, then become energized when the breaker was reset?
Just goes to show how trying to guess a problem without being there can make a fool out of you.
So far it appears that the separation of the armor jacket of the old type BX cable caused the fault by cutting into the insulation of the hot conductor.
--
Tom H


Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison

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