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#76820 03/29/01 07:54 AM
Joined: Mar 2001
Posts: 2,056
R
Member
I have a book from around 1989 that addresses this issue. It is called "Handbook of Practical Electrical Design"by Joe & Brian Mcpartland(Joe was well known back then as an authority on Electrical Systems, I wonder what became of him or Brian. Anybody?)It is common practice to splice a short piece of 90C cable, which could include "Romex" NM-B,(the suffix "-B" indicates 90C conductors. NM cable manufactured after 1985 is type NM-B) to the old cable and stick the j.b. into the ceiling(a "throw-away" or "floater")ahead of the fixture.
Quote
Originally posted by sparky:
What is a good method of installing new light fixtures that to older wiring?

These new fixtures have instructions that say that the conductor temp rating must be of a certain caliber, and that older NM may not comply...???

[Linked Image]

[This message has been edited by Redsy (edited 03-29-2001).]

[This message has been edited by Redsy (edited 03-29-2001).]

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#76821 03/29/01 11:44 AM
Joined: Nov 2000
Posts: 72
B
Member
The floater concept, appears to be one solution, for a degree of protection.
Unfortunately this will not be widely known by most homeowners.
This is again, the trend to deal with the effect, and not addressing the cause.
There is many more residential occupancies that have 60º insulated wires, than 90º.
I only hope it is not an epidemic of home fire causes.
I feel the manufacturing industry can provide a solution, to preventing the cause.

#76822 03/29/01 02:08 PM
Joined: Mar 2001
Posts: 2,056
R
Member
While we are on the subject, the popularity of retro-fitting recessed incandescent fixtures, especially with regard DIYers, presents a few other headaches. Even with electronic stud sensors, you may not detect a pipe that is a few inches back from the ceiling until you cut your hole... oops! Then there is the issue of using the connection box to loop through to other similar fixtures on the same circuit. Some of the cheaper fixtures have the box mounted directly on top of the housing, and although I've seen it done, I dont believe you are supposed to use this box as a junction to feed other fixtures. In the absence of explicit permission printed directly on the cover to do so, along with the # of additional conductors allowed, I think this is a violation. There is also the issue of a homeowner not understanding IC designations or clearances from combustible material.
Quote
Originally posted by sparky:
What is a good method of installing new light fixtures that to older wiring?

These new fixtures have instructions that say that the conductor temp rating must be of a certain caliber, and that older NM may not comply...???

[Linked Image]

#76823 03/29/01 03:07 PM
Joined: Mar 2001
Posts: 9
T
TRS Offline
Junior Member
Redsy brings up an interesting question regarding these fixtures witht the box mounted on top of the fixture. These boxes really are fairly small (and close to the heat source), but there is no statement regarding how many wires it can accomodate. Assuming that Redsy is right and these fixtures cannot, by code, be daisy-chained to others, it would render these fixtures relatively useless since it is the rare circumstance that a single fixture is to be installed. I, most homeowners, and I would bet some electricians, would assume that they were designed to accept one feed in and one feed out. If this an erroneous assumption, better that I find out now than later. Any more opinions on this?

-TRS

#76824 03/29/01 06:11 PM
Joined: Oct 2000
Posts: 5,392
S
sparky Offline OP
Member
There just does not seem to be a generic all round, good for all fix to this. It seems somewhat unfair that the manufacturing sector leaves it to the trade, or whoever actually reads the specifics. Some good suggestions and points of view here however, much appreciated.

[Linked Image]

#76825 03/29/01 08:38 PM
Joined: Oct 2000
Posts: 4,116
Likes: 4
Member
The "Floater" solution that Redsy mentions is the only 'acceptable' method I've heard so far. Perhaps the worst part is that only a relatively few people are aware of the problem. Even though the Warning is printed on the box I've yet to find a Consumer that has actually read it.

As Sparky had mentioned, it seems to be a no-win situation for the Electrician.

Bill


Bill
#76826 03/30/01 01:35 AM
Joined: Oct 2000
Posts: 2,723
Likes: 1
Broom Pusher and
Member
I admit to using the floater approach on a couple of fixture changeouts for the few Residential service type jobs I have done [other than family and friends].

I tried as much as possible to put the J-Box's outlet for the change from 60 degree NM to 90 deg. NM, in a location that was not so visiable - trying to give it some degree of hiding, rather than sticking out like a sore thumb!
All the ones I did were fortunatly in an attic space, rather than something like a shallow soffit, or 1st floor ceiling, so there was some room to work around.
The end result of having the 1 gang blank cover on the J-Box was not too bad, plus these customers understood the entire reason for it.

After reading the ideas in this thread, I was also pondering some techniques for recessed Incandescent fixtures, which will limit their potentials for fires.
Asbestos, or glass braiding Insulations [both on the conductors and the fixture it's self] would be one step, but the conductor's heat sinking would be overcome with Aluminum wire.
I don't exactly like Al, but it won't heat sink like Cu or Ag [Silver].

This temperature situation has been a consern in Fluorescent lighting for quite some time [90 deg. Insulation within X inches of the ballast], so why did it take the companies so long to require the recessed fixtures this also??
I know very little of legalistic stuff - please pardon my ignorance [Linked Image]

On a semi-related issue, I had the task of rewiring a high intensity tanning bed once, for a good customer that owned the tanning salon. I hooked up all kinds of tanning beds for him at this salon - we learned a lot from each other, too!!

The High Intensity unit had five [5] 2,000 watt HID lamps in the top [only the ballasts, capacitors, contactors, control equipment and unit subpanel was in the bottom].
The original wiring in the top used insulation similar to that used on Ballasts and Transformers [TEW, I think] - something like a max. temp. of 100 + degrees Celcius.

These conductors began to fail after 6 months of normal usage. Failure was a result of the insulation becoming "dried out" and brittle from the high levels of unfiltered UV light available, rather than just the ambient temperature it's self. When the top unit was raised / lowered as a person used the machine, it would move the conductors and create cracks in the insulation. When the lamps were first started, they were pulsed with a 2.5KV series of pulses, just as HPS lamps are. The ignitors are remote from the lamps, and in the case of this unit, they were in the lower section near the Ballasts.

Needless to say, the cracked insulation only allowed the ignition pulses to flow out through the cracked insulation.
Visible history showed that random starting was achieved over the time that the insulation's breakdown was the newest.
After repeated events, the insulation failure became too great, which kept the ignition pulses at the cracked points closest to the grounded frame. At these points, the ignition pulses would work on the conductor until there was a direct contact to the grounded frame. This would not appear as a short circuit since it was on the output of the Reactor type Ballasts.
One by one, the lamps failed to work, until they all quit. That's when I was called in.

The end results were using Glass Braided high temp silicone insulated conductors in the top part, relocating the ignitors to the top, sending the Ballasts [Reactors with intregal Autotransformers wound to the cores] out to be rewound a repotted - they had signs of overuse, resulting in charred terminals and windings.

This was an invaluable lesson to me and the client.

BTW: The company that made the unit had no knowledge of this occuring, as this was kind of a "Prototype" unit. They were so glad to be informed of this by us, that they sent reps and design engineers to the site to help with everything plus expand on the situation.

P.S. They paid for all expenses on our end!

Scott SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
#76827 04/05/01 08:24 AM
Joined: Oct 2000
Posts: 4,116
Likes: 4
Member
Scott,

Thanks for your comments. It has been fairly well understood about reccesed lighting having an issue with heat. What is less well known is that standard ceiling mount fixtures have a problem with it too, especially where there is an Attic above.

Bill


Bill
#76828 04/05/01 04:04 PM
Joined: Oct 2000
Posts: 5,392
S
sparky Offline OP
Member
A DIY'er over at do-it-yourself.com where i answer some Q's ( strictly a condition of my parole) actually read the instructions and asked about this!

this is redemming in that consumer advocates may eventualy catch on and send these cheapo fixtures back to tiawan
(just in time for China to invade!)

[Linked Image]

#76829 04/05/01 09:43 PM
Joined: Oct 2000
Posts: 4,116
Likes: 4
Member
Sparky,

Have you seen fixtures without this warning?
I haven't seen any for a long time. I thought all fixtures had this warning now.

Bill


Bill
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