I live in a building that was built in 1928. Much of the original wire is still in use, Recently, I tried to install a new ceiling fixture but the wire was so old that when I touched the cloth insulation some of it literally turned to dust. (As a result, I called an electrician to replace the wire and install the light.) In the early 1970s, the building was upgraded with circuit breakers and some new wire, but does the old wire need to be replaced? Is it a fire hazard?
From 1928? Don't forget that even bare naked wires can perform perfectly--until they touch.
As a general rule, old wiring does not need to be replaced until it is modified, added to or otherwise becomes a hazard. There are, in fact, many houses that have the original wiring from the early days, still in use. Most civilized places, however, have chosen to upgrade/remodel, meaning the old stuff was removed, either as fixtures wore out or perhaps when any new building permit was requested.
It isn't so much the wires, but in old installations they put connecting boxes between floor and ceiling, where things like wood shavings, sawdust and paper were often left after building work. This was believed to be the cause of a number of house fires when connections got loose and sparks flew. Modern wiring has all connections in boxes which are accessible. In the uk modern installations should be certified safe, and if part of the wiring is old, you will not have a fully dertified installation, and this has implications not only for fire safety, but also for for insurance claims. it is best to get new wiring for ALL the installation. Old wiring is best removed, if not for safety reasons, then at least so that in the future an electrician will not be wondering if old wiring is still connected somewhere.
Well, nothing lasts forever, and that pixie dust from your old cloth-covered wires is suggesting the end is near for your old wiring. The good news is that the first big step, new 'service panel has been done, and I'll guess included some new runs for the kitchen and whatever. I'll also guess that there's still active knob tube wiring to bedrooms and lighting (like the one that got your attention - and a good choice on pro repair). As systems changed over the years, kt was still accepted for some circuits, as it was quite safe for lighting if in good shape. By now, however, insurance coverage, if not local code may no longer allow it. It's also not adequate for receptacles, having no ground. And, with so much less use of electricity way back, it's common to find just one or two ungrounded receptacles in a room that would have a half-dozen 'grounded if built today. 'Nuff on that. Here's more info, interesting:
Of course its a fire hazard and an electrocution hazard, the whole lot needs to be replaced and brought up to current standards before you either kill yourself or burn the place down
