Low voltage question

[-robw-]

Again do what you want but don't say we didn't warn you that using a low voltage rated switch on a higher voltage circuit is not safe.

You can go back and see that I said I was not using it. I'm using one rated for 48v. I was just curious why the first one failed, and Mike helped explain why.

[sdold]

Maybe we didn't really make clear that the problem is that every time the switch is opened, that's when the little arc happens and burns the contacts some more, until after enough cycles the contacts are burned and don't make good contact anymore. The higher the voltage the bigger and hotter the spark, so when they make switches, they make the contacts beefy enough to handle whatever voltage the switch is rated for, probably for some high number of cycles.

[bcroe]

As voltage rating increases, the gap will be bigger, and extra elements for quenching
an arc start to appear. Bruce Roe

[PNPmacnab]

A friend has a high lift I work on once and a while. This solenoid keeps going bad every couple years. I have the old ones and have cut them open. Heavy duty contacts, but cheap plastic. The contacts sink below the plastic and the switch bar won't make contact. It is about construction many times. I've rebuilt many solenoids. You can sometimes get away with it with lowered current. Had a customer that used 277V relays on 480V. My hot tub has relays rated for 1 1/2hp and they use a 4 1/2hp pump, it has been working for over 20 years. A switch in a 48V circuit may only see a differential of 24V in the arc period. If the switch absolutely has to work the only way to guarantee it is to use a properly rated switch.