Mike Fleming wrote:

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There are two major issues with large mains rated toggles when used with less than mains voltages.

1. The contact material ( often plain brass) tarnishes with a non conductive layer. Regular use at mains voltage usually prevents this layer building up.

2. Grease applied to the moving parts of the switch migrates to the contacts, hardens and stops conduction.

In case 2, a squirt of WD40 often restores good operation, far as being a mains switch is concerned.


There's a third issue specifically with switches used on DC circuitry,
which is that current flow is constant and unidirectional and so the
arcing that occurs as a contact is made and broken will always be in
the same direction and will not be broken by the alternation of the
current, only by the contact gap getting large enough.


** Switches have *distinctly different* voltage ratings for AC and DC currents for exactly this reason.

240VAC switches ( and relays) are normally down rated to 24V or 32V when used with DC current of the same magnitude.

https://www.mouser.com/blog/Portals/...ig1-Switch.png

Not much relevant, however, to our present topic.


...... Phil