I just purchased two ceiling lights at Home Depot and when I got them home I noticed a warning on the box that said " use supply wire rated at 90 C, most homes built before 1985 use 60 C wire". My home was built in 1971. How do I tell if my wiring is okay. I checked the wire sheathing and the only rating I saw was 14/2 and 600v. The lights call for three 60 watt bulbs. I'm planning to use three 14w florescents. So am I all right using these fixtures?

No big deal. The spec on house wiring was raised in the 80's to give a larger margin of safety if over loaded. Keep the load on older #14 wire below 15 amps, and you won't have any problem. Your lights will draw about 0.36 amps. Make sure the #14 wire comes off a 15 amp breaker.

Many light fixtures are rated for 60 watt bulbs. If yours are, you will get in trouble if you later replace the 14 watt bulbs with 100 watt one.

Your are correct the existing wiring in a 1970 home is not 90 deg C rated. You can open a junction box or outlet and try to find the rating printed on each of the wires, may be easier to see on the white. But to save some time, take my word for it.

By the way, good catch, most people would simply install the light onto the incorrect wire. Someone actually reads the instructions!

What you can do is to purchase a small amount of #14-2 NM (Romex) or #14-2 MC or BX cable. All new wire in cable is rated 90 Deg C. You need 6 feet for each fixture. Also get two 4 in square boxes and blank plates, and four cable connectors for which ever cable you have, new and existing. Junction the new six foot cable onto the existing cable, make up the splices good, and blank the box.

Since you are installing recess fixtures, you will be allowed to push the junction box up into the ceiling, and then use the new cable to connect to the new fixture. The recess fixture is removable, therefore the junction box is accessible later, as required. No one buries splices and junction boxes in an area that is not accessible, right?

I realize you will be using compact flourscent lamps, which would cause no heat problem, but the fixture is rated for incandescent lamps, and the fixture must be installed to allow for those lamps to be used.

Thanks all, one thing though, they aren't recessed lights. Will this matter? Also, why do I need the 6ft wire?

Sorry, I had recess lights in mind, for some reason. You do say ceiling lights, my mistake. Sometimes I get something in my mind, no matter what I read.

Ok this is a different matter. Here is where common sense will play into the job. The short story is , as long as you use fluorescent lamps, then you should have no problem. It would be better if the fixture could only handle fluorescent lamps, so that no one could just screw in incandescent lamps later. These are what cause the damaging heat, which attacks the insulation of the wire.

Now for the long story. Since the wire insulation is the topic of discussion here, lets focus on that. This light outlet probably had a fixture before? Right? All you wanted to do is replace the fixture with something newer, bigger, better, whatever. What is the condition of these wires, that had been connected to a light fixture since 1971? Is the insualtion brittle? Or is it still soft and bendable? If this is a kitchen fixture,I can bet the insulation is hard and brittle, because the kitchen light is on everyday, and most people use lamps too larger. The fixtures and wiring back then did not take the heat from incandescent lamps into consideration.

The code is revised every three years, and as situations like this become apparent, the code is revised to handle these situations, for future , new installations only. The current code, and no local or state inspector has any jurisdiction to force you to replace the existing wiring to comply with the new codes. The home was built per the code in force at that time. Sure any improvement that can be made, easily, is to your favor.

I commend you for noticing the instructions and requirements. However, to comply with the technicalities is not feasible. At first, since I had recess fixtures in mind, this was going to be an easy fix, and you would have complied with the new code, and this would have offered you peace of mind. Recess lights, with incandescent lamps, are notorious to creating and entrapping heat, up inside the ceiling, and I am sure you agree, not a good thing.

If the existing insulation inside the light outlet box is brittle or hard, to a point that if bended,it breaks or cracks, then this must be treated. You can get heat shrink tubing, found at Radio Shack, home Depot, etc. You find a size with a slightly larger diameter than the wire and insualtion, slide it over to cover the old insulation, and use a hair dryer to cause the tubing to shrink down over the wire till it is tight on the wire. Similar to Saran Wrap.

This will re-insulate the wire, and make it safe, will not short out. A more drastic measure, which is only possible if there is slack cable above the ceiling, and highly unlikeley, is to pull out the box, pull out the slack, and cut back the sheathing to expose more new wire with undamaged insualtion. If the original electrician wired the house properly, there is no slack to be found.

So check the condition of the insulation, repair it as necessary. Install the new fixture, and promise to use fluorescent lamps forever. That is a good promise, incandescent lamps are a thing of the past, they use too much energy, and fail too quickly.

Again sorry for the mistake on my part.

The above question spawned a number of good replies that helped me. I need to ask a variation of the question: I have purchased a new wall mounted bathroom fixture that is 48" long with four Q100T3 100W Halogen bulbs spaced equidistant along its length. The distance from center of each bulb to the adjacent bulb is 12" and the center of the two bulbs nearest the center of the fixture is 6" on either side of the electrical box cover plate. I'll be running new wire from the wall switch for a new wall-mounted electrical box as the fixture I am replacing is a ceiling mounted dual swag lamp. :p

My question is what is the safe distance from the halogen bulbs to the ceiling? I have a tall mirror and placing the fixture directly above the edge of the mirror will result in the bulbs lying parallel to the ceiling and 15 3/4" below the ceiling. The instructions packed with the fixture has no guidance for the safe installation of the fixture other then warning of the 60C wiring in pre 1985 homes.

I want to install 4 prewired recessed lights in a ceiling with an upstairs floor. The temperature rating on the fixtures is 90 C so I will be using new MN cable. Knowing the NEC code does not permit hidden juntion boxes is this permissible?

Since they are prewired do I need the extra juntion box with in 4 feet of the fixtures?