Thermostats, regulators, switches and wiring

How to choose

Controls are matched to the task, accessories to the current and the mounting location

A mechanical thermostat switches the circuit on and off at a set temperature and does nothing beyond that. It is cheap, robust and needs no control supply – it works where the task is simple and has to keep working for years. An electronic regulator handles defrost cycles, compressor start delays and alarms; it is needed wherever holding the temperature alone is not enough.

With electrical accessories the first figure is the rated current. A switch picked “by eye” for a circuit with a heater and a fan is a typical cause of overheating contacts. The second thing is the mounting hole – the part has to fit the cut-out already made in the housing rather than force it to be reworked.

Cables and harnesses are ordered with the length and the terminations specified. A harness for an axial fan arrives ready made, with a plug on one side – this saves assembly time and removes the most common fault, a badly terminated end.

Lighting in a refrigerated cabinet works in damp and low temperatures, so an LED tube or an LED module has to be intended for it. The power supply is matched to the total power of the modules with a margin, not right at the limit.