Re: reverse polarity

mhsmom wrote:
> My friend had wiring done on an addition a couple years ago. Every
> thing worked fine TVs, VCR, vacuum, whatever was plugged in until
> recently. One day her "shop vac" was plugged in and working then
> suddenly quit. The breaker didn't blow, but eventually all the plugs
> on the circuit have quit working. An electrician friend of hers says
> the wiring is reverse polarity? Does this make sense? Can something
> caause the polarity to switch? I'm thinking maybe the breaker went bad?
> The "shop vac" still works. Sorry to say I don't have alot of info at
> this time, but it just sounded wierd to me?
> Thanks,
> MHS MOM
>

Reverse polarity would not cause the problem, cannot cause
the problem, and did not cause the problem. All the stuff
you mention will work fine, whether the polarity is normal
or reversed. It is quite possible that the polarity IS
reversed. The term "Reversed polarity" as applied to 120
vac receptacles, means that the neutral wire and the hot
wire are reversed. The ONLY way that can happen is by
a wiring error by the installer or by someone who worked
on the circuit later. Proper wiring requires that the
white wire be connected to the neutral bus in the service
panel, and to the silver colored screws at the receptacle,
and that the black wire be connected to the circuit breaker
at the service panel, and to the gold colored screws at the
receptacles.

Here's the likely cause of the problem: the original installer
wired the receptacles by "backstabbing" - stuffing the wire into
a hole in the back of the receptacle. That is a legitimate method,
but time has shown that circuits wired with that method are far
more prone to the kind of failure you describe than circuits where
the receptacles are wired by twisting the wire into a loop around
a screw, and then tightening the screw.


If only part of the circuit is failing, the problem is
located at either the last receptacle on the circuit that
works, or the first one that fails, like this:
ok ok ok F F F
panel===[R]===[R]===[R]===[R]===[R]===[R]
The defect is here >| | between the lines

If the whole circuit is failing, the defect is from the
panel to the first receptacle, inclusive.

If there are multiple defects, they can be anywhere.

Ed

Palindr☻me wrote:
> ehsjr wrote:
>
>>
>> Here's the likely cause of the problem: the original installer
>> wired the receptacles by "backstabbing" - stuffing the wire into
>> a hole in the back of the receptacle. That is a legitimate method,
>> but time has shown that circuits wired with that method are far
>> more prone to the kind of failure you describe than circuits where
>> the receptacles are wired by twisting the wire into a loop around
>> a screw, and then tightening the screw.
>>
>>
>> If only part of the circuit is failing, the problem is
>> located at either the last receptacle on the circuit that
>> works, or the first one that fails, like this:
>> ok ok ok F F F
>> panel===[R]===[R]===[R]===[R]===[R]===[R]
>> The defect is here >| | between the lines
>>
>> If the whole circuit is failing, the defect is from the
>> panel to the first receptacle, inclusive.
>>
>> If there are multiple defects, they can be anywhere.
>>
>> Ed
>
>
> It would help, of course, to know the OP's country! None of that you
> ahve written above would apply in the uk. The OP, IIRC, also mentioned
> that the sockets were failing one by one..until several/all stopped
> working.
>

The poster said it's the US in a post on 8/23 at 10:01.
Also said, in the original: > The breaker didn't blow, but eventually
all the plugs
> on the circuit have quit working.
which leads one to think it was a one by one failure.
And that may be true, but otoh I've encountered that
description a number of times, where the description is
wrong. What happens in those cases is that they encounter
a failure in one receptacle (#1), and plug in elsewhere to
receptacle #2. A day or a week or whatever passes, and they
plug into a 3rd receptacle (#3), and it's dead, too. So they
plug in elswhere (receptacle #4). It happens again, with the
same scenario (receptacle #5 bad, and receptacle #6 good, and
they describe the failure to the electrician as one by one
failures, when actually all three receptacles (#'s 1, 3, 5) died
at the same time, but the discovery sequence made it seem
like it was one failure after another. 100% (minus
a very small fraction) of the people do NOT know which
receptacles "belong" to a circuit. If the pattern was known
at the time of the first failure, and if there was a circuit
map showing the odd #'s on one circuit and the even #'s on
another, it's a lot more obvious.

Ed