I have a lovely client who lives on Dorchester in a 1920s brick courtyard building. She has been using us for several years, and we have done work for her parents as well. Like many of our clients, she is on the faculty at the University. She probably has more brains in her thumb than I have in my cranium....
But I digress.
Yesterday she had me over to change out a light fixture in the hallway. The one that was there (3rd picture down) was functioning, but the way the glass was held up by a threaded cap that had to be taken on and off to change bulbs had gotten to be a real pain to her. She was in the market for a new fixture, and found this sharp little number on the North side. (2nd picture down) It definitely gives that entry foyer a bit more pizazz than that bright gold brass fixture did. Sometimes a change as simple as a new fixture really spruces things up. Everybody knows that feeling of having remodeled a kitchen , tiled a bathroom, freshly painted or sanded and varnished the floors, or a hundred different projects in the home, large or small, and how good they make you feel. Unfortunately, my dear wife has been deprived of that feeling for way too long.....
But I digress.
In hanging this fixture, I noticed the very large and distinct warning label on it. It says "RISK OF FIRE. MOST BUILDINGS BUILT BEFORE 1985 HAVE SUPPLY WIRES RATED 60 DEGREES. CONSULT A QUALIFIED ELECTRICIAN BEFORE INSTALLING. FOR SUPPLY CONNECTIONS USE WIRE RATED FOR AT LEAST 90 DEGREES (Celsius) I think this warning label speaks volumes.
In the Chicago Electrical code, Table 18-27-310.16 "Allowable Ampacities of Insulated Conductors" lists the ampacity ratings of the various types of wire in use in residential and commercial construction today. There are many. The salient point here , however, is that only the modern, THHN, THWN, THW-2, XHHW, FEPB and other conductors have 90 degree ratings. This is based on the insulation around the copper, and its a science unto itself. The modern wire usually has a thermoplastic base insulation and some version of a neoprene high temperature resistant plastic jacket. The point is OLD CLOTH-COVERED WIRE DOES NOT MEET EVEN THE MINIMUM STANDARD that light fixture manufacturers call for. Even when it was brand new it didn't. Now that it is 70 years old and falling apart, it definitely doesn't.
So the next time your electrician tells you some version of "the old wire is OK if you don't overload it, or if you don't move it around too much," or some such observation, take it with a grain of salt. He may not fully understand this issue, or he (or she) may not be well-versed in retrofitting old wiring systems. But in either case, it's YOUR safety that's on the line, not his. These light fixture companies are very large and have very competent lawyers and research teams on their side. If they tell you, right out, IF YOU CONNECT THIS FIXTURE TO OLD CLOTH-COVERED WIRE AND YOU HAVE A FIRE, WE TAKE NO RESPONSIBILITY! that should tell you something.
A word to the wise, as my dad used to say....