Wiring and fuses in older houses

 

Knob and tube wiring

Knob-and-tube wiring was an innovative way of wiring houses in the pre-1930s. Essentially, wires are run through the rafters, usually along the centre beam, and held in place by porcelain knobs. When wires needed to be connected to knobs and pipes, they were soldered together to make a permanent connection. The porcelain knobs are usually placed at a distance of 15 cm from the joint to avoid stressing the wires.

The only insulation that protects the wire is the insulation of the wire itself. There is no plastic sheathing surrounding the wires, as is the case in modern applications.

One of the main reasons for using knobs and tubes is that the neutral wire is normally the wire that is turned off and on in a switch. This means that although voltage still flows through the wires, the circuit is not complete.

I call button tube "innovative" because the wires actually pass through open spaces and are not stapled to plates. The free-space aspect results in less heat build-up in the cable. The problem with running conduit is usually not the wiring itself, but what ignorant homeowners have done to it. Often homeowners make repairs or additions to the system without knowing how it works, and this can be dangerous for the next owner of the house.

Another common problem with knob and tube wiring is that mice, squirrels and other small creatures like to chew off the insulation of the wire. Exposed wires with voltage flowing through them are never a good situation. It is also important to know that the wire is meant to dissipate heat through the outdoor installation. If insulation is present, the heat cannot be dissipated, which can lead to a fire hazard.

If you have older cables, be aware that they may not be earthed. Even if your home's electrical system is still working properly, the insulation on older wiring can become very brittle and come loose in some places. This can be very dangerous for the homeowner.

Fuse boxes

Fuses are used in some older electrical distribution boxes instead of modern circuit breakers. A fuse is a round, screw-in protective device for the circuit. They are mainly made of porcelain, glass and metal.

A small piece of metal inside the fuse ensures that voltage can flow to the sockets. You can see the metal strip through the glass window on the front of the fuse, making it easy to check. If there is an overload or a short circuit in the line, the metal band breaks and the current flow in that circuit is interrupted.

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