BB. wrote: »
You will need a switch rated for the current and voltage, at DC, for your needs... AC is much easier to switch that DC because DC sustains arcing much better than AC--hence a similarly rated DC switch (even at a lower voltage) will be much heftier than the same AC switch.
For inductive loads, on the motor side of a DC switch, you can place a reverse biased diode from the negative to the positive lead (i.e., diode does not conduct electricity when power is on).
When the switch is turned on, the power goes to the motor--current flows and all is normal. When you turn off the power, the DC motor turns into a generator (plus wiring inductance) and it tries to keep the current going. This can cause several hundreds of volts across the switch and create an arc--which will continue to flow current as the switch contacts are moving apart--quickly ruining the contacts. The reverse biased diode (properly rated for voltage and current) will supply the current into the motor until it stops turning--helping to prevent arcing.
In the end, if you do not use a pump switch rated for the DC voltage/current--it will not last long unless you use it so power a separate relay which is rated for the power.
Heavy duty Pressure Switch, "GSG". Rated up to 2HP for AC, about 10 amps @ 24 VDC.
Note - although these pressure switches are rated for DC, we really recommend using them with a pump controller. Switching DC voltage eats up the contacts pretty fast at full load.
Class 9013 Type GSG pressure switches are two-pole devices for controlling electricity-driven water pumps.