Thanks for looking.

While I can do basic electrical work, Its not my profession, so I thought I
would seek some information from you professionals out there.

Mom and Dad (retired) have a kitchen light that keeps dimming for no
reason - even with new bulbs, a standard 60 watt non-floresecent. Its hooked
up to a 3 way circut, with 2 switches, one is a "mercury" switch, the other
is a regular single throw contact switch.

I have checked the wiring for possible shorts. And save for yanking it out
of the walls compleatly, I can't see any other reason for the light diming..
I remember a friend telling me about those mercury switches getting old.

Nothing else on that electrical circut is effected. I E. The other light
does not flicker/dim.

Any help/suggestions appreacated.

Turn off the fuses to see if the other lights are on that circuit. See
if that light is on an apliance circuit , or pump AC whatever. It
could be a corroded lamp socket, loose wire somewhere, maybe a bad
switch. The bottom of the socket may not be making good contact.

Bumbledor wrote:

Thanks for looking.

While I can do basic electrical work, Its not my profession, so I thought I
would seek some information from you professionals out there.

Mom and Dad (retired) have a kitchen light that keeps dimming for no
reason - even with new bulbs, a standard 60 watt non-floresecent. Its hooked
up to a 3 way circut, with 2 switches, one is a "mercury" switch, the other
is a regular single throw contact switch.

I have checked the wiring for possible shorts. And save for yanking it out
of the walls compleatly, I can't see any other reason for the light diming..
I remember a friend telling me about those mercury switches getting old.

Nothing else on that electrical circut is effected. I E. The other light
does not flicker/dim.

Any help/suggestions appreacated.



I'm not an electrician.

There is a loose connection somewhere -- it can be on either the hot or
the neutral wire, and it may be on the previous device on the circuit
that feeds the light or the switch.

Mercury switches don't ever wear out (that's part of their charm), but
there may be a bad connection where the wires connect to it.

I'd vote for a back-wired switch or outlet somewhere that has the
spring-loaded terminals that you just poke a wire in. Replace with a
screw-terminal device, or (if the wires are cut too short) a heavy-duty
backwired device that clamps the wires in the back when you tighten the
side screws. Also check the wirenuts or whatever where the light
fixture wires are tied to the house wiring.

Bob

Can you further explain "...have a bad neutral connection where two
120 volt circuits are sharing a common neutral. This is a big deal,
because you essentially end up with everything on two 120 volt
circuits being in series across 240 volts."
Can you possibly draw this bad circuit diagram with dashes and lines
and such? How can it be avoided by a DIY installer, and how can you
test for this problem?
Thanks!


Checkmate wrote in message news:cbf0na$6r3
...
On Thu, 24 Jun 2004 11:46:29 -0400, Bumbledor put forth the notion
that...



Thanks for looking.

While I can do basic electrical work, Its not my profession, so I thought I
would seek some information from you professionals out there.

Mom and Dad (retired) have a kitchen light that keeps dimming for no
reason - even with new bulbs, a standard 60 watt non-floresecent. Its hooked
up to a 3 way circut, with 2 switches, one is a "mercury" switch, the other
is a regular single throw contact switch.

I have checked the wiring for possible shorts. And save for yanking it out
of the walls compleatly, I can't see any other reason for the light diming..
I remember a friend telling me about those mercury switches getting old.

Nothing else on that electrical circut is effected. I E. The other light
does not flicker/dim.

Any help/suggestions appreacated.

Does the light dim when another appliance kicks in... like a
refrigerator or a coffee maker for instance? If so, your circuit may be
loaded up to the max. It's not a big deal, just a minor annoyance. You
could also have a bad neutral connection where two 120 volt circuits are
sharing a common neutral. This is a big deal, because you essentially
end up with everything on two 120 volt circuits being in series across
240 volts. Open neutrals are a bit tricky to trace out for the average
person. If you're able to rule out the first possibility, I'd recommend
calling an electrician to check it out. I doubt that there's anything
wrong with the mercury switch... they're pretty reliable.

In alt.engineering.electrical GeekBoy wrote:

| Can you further explain "...have a bad neutral connection where two
| 120 volt circuits are sharing a common neutral. This is a big deal,
| because you essentially end up with everything on two 120 volt
| circuits being in series across 240 volts."
| Can you possibly draw this bad circuit diagram with dashes and lines
| and such? How can it be avoided by a DIY installer, and how can you
| test for this problem?
| Thanks!

Normal circuit:

\/\/\/\/\/\/\/\/\/
=================== transformer
/\/\/\/\ /\/\/\/\
* * *
| | |
| | |
| | |
[breaker] | [breaker]
| | |
| | |
| | |
*-light--*--light-*
| | |
*-light--*--light-*
| | |
*-light--*--light-*

Broken circuit:

\/\/\/\/\/\/\/\/\/
=================== transformer
/\/\/\/\ /\/\/\/\
* * *
| | |
| |
| |
[breaker] [breaker]
| |
| |
| | |
*-light--*--light-*
| | |
*-light--*--light-*
| | |
*-light--*--light-*

Now one group of lights combined is in series with the other group
at twice the voltage. If the two groups are equal wattage, they
will each get half that voltage, ending up with the usual amount.

But, change the lights so that one side has more, such as by turning
more of them on:


\/\/\/\/\/\/\/\/\/
=================== transformer
/\/\/\/\ /\/\/\/\
* * *
| | |
| |
| |
[breaker] [breaker]
| |
| |
| | |
*-light--*--light-*
| | |
*-light--*--light-*
| | |
*-light--*--light-*
| |
*-light--*
| |
*-light--*
| |
*-light--*

Now one side (more lights) has lower resistance, and the other side
has more. The voltage will not divide evenly. The side with more
lights gets less voltage and the side with fewer lights gets more
voltage. For example the lights on the right might be getting 160
volts while the lights on the left are getting 80 volts.

The sum current flowing through the left group is equal to the sum
current flowing through the right group. That means the left group
divides its current over 6 lights while the right group divides its
same current over only 3 lights (so they get more current and burn
brighter).

A broken neutral (what this is) is hard to detect because everything
seems to be working. The steps needed to trace it, if done slightly
wrong, can result in extreme voltages applied. For example if 2 of
the lights on the right side are turned off, then you get a case
where the one remaining light ends up with all the current (though
it will now be slightly less) on its side, and thus has most of the
240 volts. Turning things OFF one by one can cause problems. The
only safe way to turn this off is to shut off the main breaker.

Then you can turn off all the individual breakers except one and
see if that one works after turning the main back on. If not, then
you almost certainly have a broken neutral.

--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------

On Thu, 24 Jun 2004 11:46:29 -0400, "Bumbledor"
wrote:


Thanks for looking.

While I can do basic electrical work, Its not my profession, so I thought I
would seek some information from you professionals out there.

Mom and Dad (retired) have a kitchen light that keeps dimming for no
reason - even with new bulbs, a standard 60 watt non-floresecent. Its hooked
up to a 3 way circut, with 2 switches, one is a "mercury" switch, the other
is a regular single throw contact switch.

I have checked the wiring for possible shorts. And save for yanking it out
of the walls compleatly, I can't see any other reason for the light diming..
I remember a friend telling me about those mercury switches getting old.

Nothing else on that electrical circut is effected. I E. The other light
does not flicker/dim.

Any help/suggestions appreacated.

After all this high-tech mumbo-jumbo, just check the center tab in the
light fixture screwshell. The screwshell has probably arced and burnt
the socket. P.S. Don't stick your finger in the socket with the switch
on! Lol!

"Bumbledor" wrote in message
...

Thanks for looking.

While I can do basic electrical work, Its not my profession, so I thought
I
would seek some information from you professionals out there.

Mom and Dad (retired) have a kitchen light that keeps dimming for no
reason - even with new bulbs, a standard 60 watt non-floresecent. Its
hooked
up to a 3 way circut, with 2 switches, one is a "mercury" switch, the
other
is a regular single throw contact switch.

I have checked the wiring for possible shorts. And save for yanking it out
of the walls compleatly, I can't see any other reason for the light
diming..
I remember a friend telling me about those mercury switches getting old.

Nothing else on that electrical circut is effected. I E. The other light
does not flicker/dim.

Any help/suggestions appreacated.

Hire a good electrician, you cheap *******!