The earliest remnant of Chez Melendy's wiring was knob and tube. None of this wiring was still in use but knobs and tubes are scattered throughout the house on the framing members. Knob and tube wiring is a system where exposed wires, held in place by porcelain insulators, are run along the house's framing members to reach light fixtures mounted in the center of a room. Wherever the wiring has to penetrate a beam or wall, a porcelain tube is used as an insulator. This style of wiring saw wide-spread use in the early 20th century because it was a safe and easy way to retrofit existing homes with electricity.
It isn't always necessary to replace knob and tube wiring if it's in good shape, but the exposed wires have to be protected from coming in contact with anything such as blown-in insulation or fiberglass batts. Because modern living often requires use of attics and basements in ways they weren't used back when knob and tube wiring was installed, it's probably best to replace it. It's also likely that any rubber or cloth that was used as insulation for this kind of wiring is now degraded and would have to be replaced anyway.
In the last post I said that the patchwork of wiring that we found in Chez Melendy wasn't a crime. I should clarify that splicing new and up to date wiring to old circuits is risky. It's possible that the old section of wiring may have degraded to a dangerous state even if it was originally designed to handle the amperage designated at the breaker box.
The next generation of wiring I encountered in the Chez, and the oldest that was still in use, was the two-conductor, cloth-insulated wiring surrounded by flexible metal conduit known as Greenfield. This was all in pretty good shape. It ran throughout the ceilings in the house providing service to light fixtures at the center of every room. On each floor, within the ceiling, junction boxes radiated conduit like tentacles of a giant metal octopus. It seemed a shame to pull all this stuff out, but even though it was in good shape, Greenfield doesn't provide the continuous ground the same as modern Romex does and the likelihood for failure of the cloth-insulated conductors is a fire hazard. I did, however, use some of this old stuff to wire a couple of light fixtures where the wiring is exposed -- a sentimental nod to Chez Melendy's electrical pedigree.
At some point the owners of the house decided to add receptacles to their electrical service. This was accomplished by running an early version of Romex from the Greenfield junction boxes down through the walls to outlets mounted in the baseboard. By adding receptacles, the owners provided both a doorway into the convenience of modern residential electric but also set the stage for a hazardous situation down the road.
The old Romex that was used to service the wall outlets was ungrounded and made of two-conductors surrounded by an asphalt impregnated cloth insulator. This material was severely degraded by the time I discovered it in the walls. It was dried and cracked and an accident waiting to happen. I was happy to pull this stuff out and, if for this discovery alone, I was glad to have decided to gut the house and rewire it.
The next step in the evolution of Chez Melendy's electric service was the addition of a breaker panel and a new circuit for kitchen appliances. It was probably the need for the new kitchen circuit that prompted the addition of the breaker panel, and some might argue the Melendys would have been better off saving themselves the expense and just adding the circuit. The panel may have cleaned things up a bit but for all the other circuits in the house, it was simply a new link in a weak chain. The fuses that controlled the old circuits were probably safer for them than the new-fangled breakers.
This was the state at which I inherited the wiring. A 60's era breaker panel with 14 gauge Romex (smaller gauge grounding wire) feeding into older circuits of Greenfield.
Next time I'll get into my foray into re-wiring the entire house.