Peter McCarthy Electric Co., Inc.
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Cloth-covered wire NEVER gets better with age
|Posted on November 2, 2014 at 8:03 PM||comments (766)|
ALWAYS LOOK BELOW THE SURFACE!!! (Or above the ceiling)
|Posted on May 5, 2014 at 10:00 AM||comments (196)|
Cloth-covered 1920s wire; A FIRE waiting to happen!!!
|Posted on February 17, 2014 at 7:45 PM||comments (89)|
Nice new fixture in Hyde Park
|Posted on June 27, 2013 at 10:35 AM||comments (501)|
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....
Wire lasts years, not generations!
|Posted on May 9, 2013 at 3:52 PM||comments (362)|
As a small businessman, I wear many hats. Electrician, supervisor, account executive, marketing manager, outreach co-coordinator, chief engineer. And Blog/online/IT guy. Of this post, I was never trained. I I grew up to late to have computer pics be intuitive to me in any way shape or form. Hence, these 4 pictures that were vertical on my desktop appear horizontal on my web page. Already out of time, cant spend 45 minutes figuring out how to rotate them. Bear with me.
BE THAT AS IT MAY.......
We are rewiring the public stairwells in a twelve unit building here in Hyde Park. It is a 1910s or 20s building, with the lovely period detail and elegant architecture. In this case, however, it also has the original cloth covered wire that has aged so far beyond its natural safe life span that it was was I consider a "Clear and present danger." The top two pictures are one ceiling chandelier and one wall sconce. These fixtures are original to the building and as it looks to me have never been changed, modernized or examined for safety. Behind the wall sconces and above the ceiling fixture canopies the wire had just crumbled away to being bare. Years, decades even, of overheating, drying out, general wear and the inherent limitation of the materials in vogue in the "Bees knees and 23-skidoo days" are abundantly clear. This was, no doubt, a fire waiting to happen.
If you have old fixtures that look like this in your building, you would be well advised to have a real electrician check things for you. You may be very, very glad later!
Rewiring a condominium on Woodlawn.
|Posted on December 26, 2011 at 8:30 PM||comments (129)|
Rewiring and remodeling; Cloth-covered wire part 2
|Posted on April 27, 2011 at 9:09 PM||comments (166)|
I originally wrote this as a reply to Kef on his comment. He had raised the point that away from the junction boxes, cloth-covered wire can seem "just fine."Thanks so much for your insight. You make some valid points. I think is most critical one is that at the point of use is where the cloth-covered wire insulation has generally deteriorated to the point of no return. I agree, I have pulled out some runs of 1930s -1950s cloth covered wire where other than being crunchy and non-pliable, it is just about as it was new, except for the last 6-8 inches at each side that has crumbled away to nothing. In general at the fixture locations where they have been subject to excessive heat as transferred through the sheet metal light fixture housing, that is where they are completely shot. That is where the fire hazard is most prominent. The fact that in most vintage fixtures, the bulbs were hanging further away from the wire than in the modern surface mounted fixture makes a big difference. Often that fixture was the only light in the room, so in some cases fixtures have been overlamped with 100 or even 150 watt bulbs for years. If you or your sister ever had an "easy bake oven" as a kid, the similarity is remarkable. Add to that the lack of air circulation/cooling space in the older style "pancake" boxes, which can be as shallow as 1/4" or 3/8", which force the wires to be crammed very tightly against the baking sheet metal housing, and its not a surprise that they decay and insulation crumbles away to nothing once they are disturbed. Unfortunately, they almost always do. If you look closely, most vintage fixtures had a fairly deep cup-shaped canopy. They assumed the building premises wiring would be contained there, and they allowed space for it. The 1 1/2" deep 1900 or 8-b (Octagon) boxes we use today, with their ample depth to provide air circulation, lower ambient temperatures, and to contain the wiring within the recessed box of the ceiling did not exist. Thus if you place a hot pan of sheet metal fixture housing and screw it up tight to the ceiling to look flush and proper to our modern eyes, you are asking for trouble in an old cloth-covered wired house. I try to recycle the copper wire so it is not completely lost. In a sense, its a shame that just the 6-8" of wire at each end can render the whole 25 or 30 foot piece useless. But I also find slight oxidation has occurred on the copper that has been exposed for generations, which is best to be rid of as well. With labor costs much higher than wire cost, it always makes economic sense to replace it. Plus, the gain in available space in the conduit when the thick cloth and rubber insulation has been extracted, which allows for higher conduit fill and more circuits to be pulled into the same size conduit more than offsets the loss at the other end. I like your long term perspective, Kef. Are you an engineer? Thanks, too, for your comment. It's nice to know this "pontificating" of mine is not just floating off into cyber-space and not doing the world any good!
Cloth covered wire...How well does it Hold up? Judge for yourself....
|Posted on April 18, 2011 at 2:46 PM||comments (286)|
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