Continuity Testing Appliance Switches

Continuity testing, as related to an elec­trical component, is the check of a part for an “open” or “closed” circuit.

Is there a path or not? References are made between a “closed” (continuity) reading and an “open” (no continuity) reading.

Electrical components fall into two general categories.

1. LOADS - Devices that use or consume electricity. Examples would include drive motor, heating elements, lamps, timer and solenoid coils.

2. SWITCHES – Devices that control the supply of electricity to the load or loads in a circuit. Examples include door switches, timer contacts, selector switch and relay contacts.

Continuity tests of “load” devices will show varying levels of resistance from very low for some transformer and motor windings to very high for some timer motors and components on electronic control boards. Usually it is more important to know if there is a path for current flow through a device (continuity) than to know the exact resistance (ohms) of the device.

Continuity tests of switches will show virtually no resistance across closed contacts. Resistance, even low values indicates burned or dirty contacts in a switch.

Continuity testing is a process of eliminating those electrical components involved in a given function of the appliance, until the inoperative part is found. By reviewing the list of possible electrical problems under a given condition, and then performing appropriate continuity checks on the parts involved, you should be able to locate the electrical component which is inoperative.

When checking components or circuit paths for continuity, external wiring should be disconnected to eliminate false readings through external paths. Isolate what you want to test.