Wiring the heating films

The weak point of an older installation

We have replaced heating films more than thirty years old. In almost every case the carbon web was intact and it was the connections that had failed, oxidised. Carbon does not rust and does not fatigue; the metal that feeds it does. The whole service life of an installation is therefore decided at that precise point.

Why tinned copper

Tinning protects the copper from oxidation by air and moisture, including in a closed plenum where condensation is possible. A bare conductor tarnishes, its contact resistance rises, it heats locally, and the cycle accelerates on its own until the circuit opens.

The choice of connector

We use crimp terminals with heat shrink sleeving. The crimp provides the mechanical contact, the sleeve provides insulation and sealing of the joint. A conventional screw terminal block loosens with expansion cycles and has no business above a closed ceiling.

Checks before closing up

Continuity of each circuit, absence of insulation fault, and a full warm-up with a thermal camera check. Those three checks are made while everything is still reachable. After the board or the fabric goes up, you have to open again.

Identification

Each circuit is identified and marked on the layout drawing. Ten years from now somebody will need to know what runs where, and that somebody will not be the person who fitted it.

The lever terminals we supply are presented on the page devoted to them, and the replacement of an older installation on the page of the job under a roof.