Light fixtures with 60 degree conductors

[Greg1707]

I was installing a single bulb 60 watt light fixture today for a customer in a 40 year old house. As I was installing the fixture she was reading the instructions. She pointed out that the instructions stated something like the following: "warning, this fixture requires 90 degree conductors. Most houses built before 1985 have 60 degree wiring. Please consult an electrical professional before installing this fixture!" Well, she asked me if it was okay to install this fixture since her house was built in 1958.
I know about romex and 60 vs newer 90 degree, but what is the proper response to the warning contained in the installation material for the light fixture?

 

[gndrod]

fixture vs house wiring

fixture vs house wiring

Conductor wiring in a fixture-luminaire usually is rated 90 or 105 C as found in fluorescent ballast wiring. The '"house" conductor insulator rating of 60 or 90 C is still acceptable for hookup connections in the outlet. Conductor wire hookups inside the fluorescent housing must have a 3" separation from the ballast [410.33] unless the wiring is rated 105 C. This may be what was meant in the original rating interpretation. rbj

 

[bob]

The instructions are referring to the wiring in the fixture and the tap conductors that enter the fixture. The tap conductors need to be 90C rated and at least 18 inches long. See 410.67C

 

[peter d]

If the conductors are in bad shape, you can install heat shrink tubing over them, or slide new THHN insulation (stripped from romex or THHN scraps) over the conductors as well.

 

[infinity]

I know about romex and 60 vs newer 90 degree, but what is the proper response to the warning contained in the installation material for the light fixture?

I would follow the warning. If the house burns down it's you they're coming to get. We simply refuse to install fixtures with 60 degree existing conductors and a fixture that requires 90 degree conductors.

 

[peter d]

I would follow the warning. If the house burns down it's you they're coming to get. We simply refuse to install fixtures with 60 degree existing conductors and a fixture that requires 90 degree conductors.

I agree that refusing to do the work is the best course of action from a liability standpoint. But then the H.O. will get another electrician to put the light in, or a handy-hack, or they might even attempt the installation themselves.

In a perfect world we would refuse to install lights in this situation. In the real world the lights get installed because not everyone is willing or able to pay to have their house rewired to hang a few lights.

If it were me I would heat shrink the conductors and be done with it.

 

[Pierre C Belarge]

I agree that refusing to do the work is the best course of action from a liability standpoint. But then the H.O. will get another electrician to put the light in, or a handy-hack, or they might even attempt the installation themselves.

In a perfect world we would refuse to install lights in this situation. In the real world the lights get installed because not everyone is willing or able to pay to have their house rewired to hang a few lights.

If it were me I would heat shrink the conductors and be done with it.

Why let others' actions determine what you have already determined to be an improper installation. Someone else installing a violation should not be a reason for another to do the same...

 

[tonyou812]

I have no problem telling people that I cant install their lights. Especially when they dont have a UL sticker let along faulty wiring. This is part of being a professional in my opinion.

 

[bob]

I was installing a single bulb 60 watt light fixture today for a customer in a 40 year old house. As I was installing the fixture she was reading the instructions. She pointed out that the instructions stated something like the following: "warning, this fixture requires 90 degree conductors. Most houses built before 1985 have 60 degree wiring. Please consult an electrical professional before installing this fixture!" Well, she asked me if it was okay to install this fixture since her house was built in 1958.
I know about romex and 60 vs newer 90 degree, but what is the proper response to the warning contained in the installation material for the light fixture?

You are not interpreting this correctly. The wiring within the fixture must be rated at 90C. That includes the tap entering the fixture splicing box. The wiring presently in the house can be 60C. The tap conductors need to be 90C rated and at least 18 inches long. See 410.67C

 

[Greg1707]

Installing light fixtures

Installing light fixtures

I have no problem telling people that I cant install their lights. Especially when they dont have a UL sticker let along faulty wiring. This is part of being a professional in my opinion.

The majority of houses in this country were built built before 1985. Therefore, they must have 60 degree Romex. Electricians surely install thousands of light fixtures every day in these houses. What is really going on? Are there actually electricians refusing to install light fixtures because the house was wired with 60 degree Romex? What do you mean about the 18" of new conductor? There is a box in the ceiling with 60 degree Romex. What do you do when you arrive at a pre 1980 house to install a light fixture?

 

[LarryFine]

The tap conductors need to be 90C rated and at least 18 inches long. See 410.67C

Where do you put that 2 x 18" wire in an old steel pancake box with two BX clamps inside it?

With that kind of compaction, the length isn't going to provide any useful heat isolation.

410.67(C) certainly doesn't apply here. Where's the box 1' away with the 18" in AC or MC?

 

[macmikeman]

Grainger sells shrink tube with a 120degree centigrade rating by the roll. It is not so expensive to make the install prohibitive. I use it on old houses when I have to install new lights and cannot put a splice box close by such as the ground floor ceiling on a two story dwelling. It may not really satisify code possibly, but I am at least trying to mitigate a theoretical problem.

 

[bob]

Where do you put that 2 x 18" wire in an old steel pancake box with two BX clamps inside it?

With that kind of compaction, the length isn't going to provide any useful heat isolation.

410.67(C) certainly doesn't apply here. Where's the box 1' away with the 18" in AC or MC?

Every code reference will have physical problems at some time making it difficult to install.
The point is just because a house has 60C conductor does not prevent a
fixture like the OP presented from being installed.

 

[suemarkp]

I always assumed this warning was about the high temperatures generated by the fixture and how it cooks the wires in the ceiling box above it. In older houses, the circuits for receptacles were often routed through ceiling boxes first and then they octopus out from there. So some heavy 15A load in a wall receptacle will be going through those conductors in the hot ceiling box and probably overheat things.

So what I do for my own lights (in a house built in the mid 60's), is I'll install something which says use only 90C wiring if the only load on the wires in the ceiling box is the light itself (so dead ended light circuits only). Still may not be legal, but its the best I can do without ripping everything out. If 90C and full 15 or 20A is OK through 90C wires, 60C shouldn't be too far off if the load is only 1 amp. I also tend to use fluorescent edison base lamps now too which further reduce the heat.

I can't believe this warning is only applying to the fixture wires. This light fixtures almost always have their own 105C pigtails which you wire nut to the branch circuit conductors in the ceiling box. Why would they mention 1985 when the NM switch to 90C occurred if the ceiling box branch circuit wires weren't the issue?

 

[Pierre C Belarge]

I was installing a single bulb 60 watt light fixture today for a customer in a 40 year old house. As I was installing the fixture she was reading the instructions. She pointed out that the instructions stated something like the following: "warning, this fixture requires 90 degree conductors. Most houses built before 1985 have 60 degree wiring. Please consult an electrical professional before installing this fixture!" Well, she asked me if it was okay to install this fixture since her house was built in 1958.
I know about romex and 60 vs newer 90 degree, but what is the proper response to the warning contained in the installation material for the light fixture?

410.11 Temperature limit of Conductors in Outlet Boxes.
Limits the type of conductor in the outlet box that can be used with certain types of fixtures. Surface mounted type fixtures comes to mind for me. In the last few years, manufacturers have installed a large number of labels on these types of fixtures so you cannot make the mistake. If you do, the onus falls on you.
When working in the older homes that have 60C type conductors, you should notify your customer.

 

[Pierre C Belarge]

So some heavy 15A load in a wall receptacle will be going through those conductors in the hot ceiling box and probably overheat things.

If 90C and full 15 or 20A is OK through 90C wires, 60C shouldn't be too far off if the load is only 1 amp. I also tend to use fluorescent edison base lamps now too which further reduce the heat.

I can't believe this warning is only applying to the fixture wires. This light fixtures almost always have their own 105C pigtails which you wire nut to the branch circuit conductors in the ceiling box. Why would they mention 1985 when the NM switch to 90C occurred if the ceiling box branch circuit wires weren't the issue?

This restriction is not due to the load/current flow in the conductors. The restriction is due to the temperature of the lamp and its effects on the conductor insulation over time. The old 60C conductors stand no chance against the temperature of some of these fixtures.

 

[Pierre C Belarge]

My House

My House

I hired an electrician (even though I am capable of the installation) to wire my kitchen and dining room, he also did some work in the living room. When it came time to do the fixtures, he called me to tell me the conductors in the ceiling boxes was 60C.

I had him abandon the existing wiring and install new wiring...switch and receptacles as well. He made swiss cheese of the place while doing so.
My point is, that I do as I ask.

P.S.
He filed and had an inspection by another inspector.

 

[suemarkp]

This restriction is not due to the load/current flow in the conductors. The restriction is due to the temperature of the lamp and its effects on the conductor insulation over time. The old 60C conductors stand no chance against the temperature of some of these fixtures.

But aren't they related? A light fixture box could have a full 20A going through its conductors because of how the wiring was layed out. If using 90C wire, the wires would still need to be able to tolerate this load in addition too all the heat from the lamp. So now how do things change when a 20A load is reduced to a 1A load? Are we still over the limit for a 60C wire, just under, or what?

The only way I can hope to figure this out is as follows:
A 90C #12 wire is rated at 30A. If we wish to keep its 20A ampacity, this allows for a derating of 0.66 due to temperature factors. Looking at 310.16, the correction factors for temperature indicate an ambient temperature of 60C would keep the correction factor near .67 (this is actually between two table values of .71 (for 56-60C) and .58 (for 61-60C)). So if the ambient is 60C, that leaves no margin for heating due to current flow if the wire is only 60C rated. But it is very close.

 

[wireman3736]

This is a commentary in the 08 handbook

Branch-circuit conductors run to a lighting outlet box are not permitted to be subjected to temperatures higher than those for which they are rated. Take, for example, conductors that are rated 75?C and are to supply a ceiling outlet box for the connection of a surface-mounted luminaire or attached outlet box of a recessed luminaire. The design and installation of the luminaire should be such that the heat of the lamps does not subject the conductors to a greater temperature than 75?C. These types of luminaires are listed by Underwriters Laboratories Inc. based on a heat-contributing factor of the supply conductors of not more than the maximum permitted lamp wattage of the luminaire.

 

[bob]

But aren't they related? A light fixture box could have a full 20A going through its conductors because of how the wiring was layed out. If using 90C wire, the wires would still need to be able to tolerate this load in addition too all the heat from the lamp. So now how do things change when a 20A load is reduced to a 1A load? Are we still over the limit for a 60C wire, just under, or what?

Sue
There are no calculations required. This is strictly a heating problem. If you had a fixture that required 10 amps
and you were using a 60C rated #12 copper conductor you could not use it in the fixture that required 90C conductor rating. The reason is that the temperature in the fixture junction box heats up to a temperature that exceeds 60C. Apparently it exceeds 75C also or you would be allowed to use it. Wiremans comments above describe the problem perfectly.







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