On a space heater, I replaced a 20A DPST switch with a 16A one I found at radio shack. I am unsure about the amperage of the circuit itself (how to find this?) but I'm assuming it's 20A or else the company would have bought a cheaper switch. Seems to be working now, and I have a 20A switch on its way, but am I going to burn down the house in the interim?
In other words, I know I'm currently using the wrong switch, but would you consider it dangerous to leave this heater on until I get the proper switch?
Best Answer
Replacing a 20 A switch with a 16 A switch without knowing anything else is a REALLY BAD IDEA.
Chances are you won't burn your house down, but how lucky do you feel? Fortunately, 25% overcurrent thru a switch is unlikely to do more than burn out the contacts such that the switch either won't close properly anymore or weld the contacts shut so that it is permanently on. If the switch is in a metal box so that nothing too bad would happen if it reached the melting point of plastic, you probably won't burn your house down.
Even if the space heater doesn't draw more than 16 A, you still have a problem. Suppose stuff happens (which it regularly does to space heaters, they are one of the leading causes of house fires and electrocutions) so that the power wires get shorted. You want the breaker to trip to shut off the circuit. This might not happen if the switch is a weaker link than the breaker. Instead of the breaker popping, the switch might catch fire. In general, it's a good idea to use a switch rated for at least the trip current of whatever power segment it is on.
To paraphrase Dirty Harry: Do you feel lucky? Well do you, punk? Go ahead, use a 16 A switch. Make my day.