Why is a 20 amp switch hot to the touch?

Answer 1

Most electrical switches even if designed and built correctly have a small amount of resistance to current flow.The upshot of this is that power is lost in the switch when current flows, ( from Ohm's Law: W=I x I x R, where W = watts, I = Amps , R = Ohms) In conclusion, where current flows through a resistance ( in this case the switch ) power is lost in the form of heat. Generally a 20A switch would be 'warm' to the touch, if it is 'hot' then this may indicate that the switch has a fault, for example a loose joint/connection or deteriorated contacts. Most electrical switches even if designed and built correctly have a small amount of resistance to current flow.The upshot of this is that power is lost in the switch when current flows, ( from Ohm's Law: W=I x I x R, where W = watts, I = Amps , R = Ohms) In conclusion, where current flows through a resistance ( in this case the switch ) power is lost in the form of heat. Generally a 20A switch would be 'warm' to the touch, if it is 'hot' then this may indicate that the switch has a fault, for example a loose joint/connection or deteriorated contacts.

Answer 2

Do you mean ' a bit warm' or 'hot enough to burn a finger' ?

If the second one you have a major problem, switch off the power and get an

electrician to take a look.

Heat is a natural result of a current flowing through any wire or connection. Normally the heat generated within a 'normal' domestic rated switch is so small it can not be detected let alone felt. Heat always indicates a fault, and it needs to be resolved quickly. Left alone someone may get hurt or a major fire can be caused - at best you will have the cost of having the switch and possibly an entire circuit replaced. Fix it fast - but carefully - electricity is always dangerous. If in any doubt at all get a professional.

Four common reasons why a switch might get warm:

1. You have overloaded it, the device being switched is more powerful (drawing more current) than the switch is designed to handle. Change the device or replace the switch as appropriate.

2. The device is faulty and drawing too much power. Turn it off, disconnect it and have it checked out.

3. One or more of the wires to the switch is not properly connected, the screw holding it is possibly loose or damp may have caused corrosion of the contacts. Turn off the power to the switch, remove the cover and check the connections (if you don't know how then get an electrician).

4. Switches contain a small spring to hold the moving contact in good electrical connection with the stationary contact. If the switch is old or has been misused the spring may have failed or weakened causing a poor contact. If the switch does not operate with a good solid 'click' when operated it needs to be replaced.

There are several other answers to this question around - check them out too.