I have a sp3t switch, wich is rated at 300mA 4vdc with a contact resistance of 70MΩ max

can someone tell me how much mA I can draw on 24vdc, I prefer with formula, so I can understand it myself to

 

Nothing - it's only rated at 4V DC.

 

70 MΩ seems a bit high for the resistance of a switch. Could you possibly mean 70 mΩ? It is pretty bad when you are off by a factor if one billion.

Bob

 

Hello,

Do you have a link to the datasheet?
As said, use the correct prefix.

Bertus

 

so sorry, seems I messed up with the letters.
https://www.alibaba.com/product-detail/3-way-slide-switch-LY-SK_1626406105.html

the switch would be used once as "path chooser" on a pcb ,it would not be used to switch while under power.

 

The rating given in your link are meaningless. They are contradictory. In one place it says 4 volts DC maximum it then says 50 mA maximum current at 12 volts.
There is no formula for working out a voltage or current rating at values different from the manufacturers ratings. Just keep below the manufacturers ratings.

Les.