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Home > Archive > Home Repair forum > August 2005 > New Light Fixture / Old wiring
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New Light Fixture / Old wiring
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| Jim Taylor 2005-08-31, 1:21 am |
| I purchased a energy efficient ceiling fixture to replace a kitchen
light. (It is not recessed). The directions warn that it should not be
connected to house wire not capable of withstanding x degrees Celsius.
(I think x is 70 or 90). Since my house was built in the 1960s, I
don't have any idea how hot max the wire is designed to get, but IIRC
most wire of that era was designed for 60 C.
So what is the proper way to wire a new fixture? I'm surprised the
wire temperature max rating is such an issue, the enegy efficient
florescent lighting seems to be much cooler than incandescent.
Thanks!
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"Jim Taylor" <jim.taylor@hax.hax> wrote in message
news:431529D3.D19544F9@hax.hax...
> I purchased a energy efficient ceiling fixture to replace a kitchen
> light. (It is not recessed). The directions warn that it should not be
> connected to house wire not capable of withstanding x degrees Celsius.
> (I think x is 70 or 90). Since my house was built in the 1960s, I
> don't have any idea how hot max the wire is designed to get, but IIRC
> most wire of that era was designed for 60 C.
>
> So what is the proper way to wire a new fixture? I'm surprised the
> wire temperature max rating is such an issue, the enegy efficient
> florescent lighting seems to be much cooler than incandescent.
>
> Thanks!
As far as I know your correct about the residential wiring of the era.
My guess is that the manufacture said 90 c. Which is what the newer
residential wire is rated for, I believe.
You could always pig tail a piece of thhn or thwn to the home wiring and
then connect to the fixture.
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| I think it's an easy method for the manufacturer to exempt themselves from
liability in case of fire. Most houses don't have 90 degree wire and I doubt
most people are going to rewire the outlet box just to accommodate fixtures
with that listing. Having said that, there are however fixtures made that do
generate a lot of heat on the outlet box they are attached to and the wire
supplying those fixtures should be of 90 degree rating
news:431529D3.D19544F9@hax.hax...
>I purchased a energy efficient ceiling fixture to replace a kitchen
> light. (It is not recessed). The directions warn that it should not be
> connected to house wire not capable of withstanding x degrees Celsius.
> (I think x is 70 or 90). Since my house was built in the 1960s, I
> don't have any idea how hot max the wire is designed to get, but IIRC
> most wire of that era was designed for 60 C.
>
> So what is the proper way to wire a new fixture? I'm surprised the
> wire temperature max rating is such an issue, the enegy efficient
> florescent lighting seems to be much cooler than incandescent.
>
> Thanks!
>
>
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| The light itself is cooler, but florescent lights have a "ballast" which
can get to be quite hot. (At least with commercial fixtures.)
Heat travels up, also heat can get trapped with insulation, in the metal
box holding the electrical wires, etc.
I've seen insulation from old wires just crumble when I removed a wall
fixture in a bathroom. And that was not even a ceiling fixture. Some of the
insulation had fallen off by itself. Note that this fixture was part of a
metal medicine cabinet, so could have been a shock hazard as there was no
grounding!
The heat from the fixture wrecked the insulation on the old wiring.
I would replace the wiring whether it needs it or not, since it may have
been damaged by the previous fixture. The new stuff is *so* much safer than
the old (grounding, high heat insulation, etc.)!
"Jim Taylor" wrote in message
> I purchased a energy efficient ceiling fixture to replace a kitchen
> light. (It is not recessed). The directions warn that it should not be
> connected to house wire not capable of withstanding x degrees Celsius.
> (I think x is 70 or 90). Since my house was built in the 1960s, I
> don't have any idea how hot max the wire is designed to get, but IIRC
> most wire of that era was designed for 60 C.
>
> So what is the proper way to wire a new fixture? I'm surprised the
> wire temperature max rating is such an issue, the enegy efficient
> florescent lighting seems to be much cooler than incandescent.
>
> Thanks!
>
>
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| Bill wrote:
> I've seen insulation from old wires just crumble when I removed a wall
> fixture in a bathroom. And that was not even a ceiling fixture. Some of the
> insulation had fallen off by itself. Note that this fixture was part of a
> metal medicine cabinet, so could have been a shock hazard as there was no
> grounding!
>
I've run acoss the same thing - you move the wire and the insulation
still remianing cracks off. Old circline flourescent fixtures could
cause this.
> The heat from the fixture wrecked the insulation on the old wiring.
>
> I would replace the wiring whether it needs it or not, since it may have
> been damaged by the previous fixture. The new stuff is *so* much safer than
> the old (grounding, high heat insulation, etc.)!
>
The solution? Get a fixture that is rated for 60°C supply wiring. It is
common for fixtures to have insulation built into the top to limit heat
problems. I'm not impressed with the fixture manufacturer. Seems obvious
a lot of these will be installed with 60°C wiring.
Bud--
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| HorneTD 2005-08-31, 1:21 pm |
| SQLit wrote:
> "Jim Taylor" <jim.taylor@hax.hax> wrote in message
> news:431529D3.D19544F9@hax.hax...
>
>
>
> As far as I know your correct about the residential wiring of the era.
>
> My guess is that the manufacture said 90 c. Which is what the newer
> residential wire is rated for, I believe.
> You could always pig tail a piece of thhn or thwn to the home wiring and
> then connect to the fixture.
>
>
No you can't. The lower rated 60C rated conductors need to be far
enough away to be unaffected by the heat the fixture gives off. If the
space above is accessible you move the old cables into a Jbox and run a
cable from that Jbox to the fixture box. If the old cables are not
relocated the heat from the fixture will cook the insulation right off
the wires and they will fault out. Because the process is gradual it
has a higher likelihood of arcing faults that can kindle a fire.
--
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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| maradcliff@UNLISTED.com 2005-08-31, 5:21 pm |
| On Tue, 30 Aug 2005 23:53:55 -0400, Jim Taylor <jim.taylor@hax.hax>
wrote:
>I purchased a energy efficient ceiling fixture to replace a kitchen
>light. (It is not recessed). The directions warn that it should not be
>connected to house wire not capable of withstanding x degrees Celsius.
>(I think x is 70 or 90). Since my house was built in the 1960s, I
>don't have any idea how hot max the wire is designed to get, but IIRC
>most wire of that era was designed for 60 C.
>
>So what is the proper way to wire a new fixture? I'm surprised the
>wire temperature max rating is such an issue, the enegy efficient
>florescent lighting seems to be much cooler than incandescent.
>
>Thanks!
>
I can not understand how a florescent should get that hot, You might
call the manufacturer and question them in this matter. But if thats
what is required, see if you can get to the cable from your attic or
something. Turn off the power, remove the cable, put a junction box
on the next rafter and run a piece of approved wire to the old ceiling
box.
One note, on all the old and new enclosed indecesant bulb fixtures, I
always drill a few holes in the base, (about 1/8 to 1/4 inch) near the
ceiling. That allows much of the trapped heat to escape. It's not
all that noticable and saves the wires.
Mark
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