Im currently setting up a Cohesion3D controller board, kinda learning along the way.
on the board the connection for Endstops say “+5v”
I have some mechanical endstops on hand, and would like to know if their compatible.
on the side they say “3A/5A AC250/125V”
does this mean they are rated up to 125V? but could accept 5V from the board?
Yes, those are maximum ratings. You are fine.
In general, switches will work at much higher AC than DC voltages, because AC goes through zero volts many times per second, which helps stop an arc between the contacts. DC switches above 24V or so tend to be more specialized, and in general you do want to pay close attention to the maximum DC voltages.
But for sensors, not only is it low voltage, but also there is a lot of resistance and thus low current, so you just don’t have to worry about it.
Thanks very much, got things all worked out 
