SPDT switch > 20A @ 32VDC?

GordonThree wrote:

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Why double pole? No need to switch ground if that's the case.

Double throw, not pole.

brulaz wrote:
I have an extra DC breaker but it's not double throw.
A relay sounds like a better idea.
But one with double throw and centre off?
Could use the DC breaker to provide the Off function I suppose.

Normal DC breakers aren't designed for switching loads, but if you're only planning once in a blue moon maybe not a problem.

Why double pole? No need to switch ground if that's the case.

What about doubling up on the contacts of DPDT to act like a SPDT?

At higher current one contact will arc before the other degrading the switch.

The voltage rating is for isolation. It's the maximum voltage that can be applied to the switch. A 20A 250V switch works just as well as a 40V switch at 12V. The contact resistance most likely will be different.

A power supply set to the proper voltage can directly replace solar panels.

enblethen wrote:
OP:
would you most what you are trying to power? Please give make and model.

As inputs:
- Meanwell RSP500-27 Power Supply (have seen it go up to 700W out) at 32.5V on one leg of the SPDT switch.
- 340W of Solar panel Voc=47V, Isc=10A on the other leg.


Centre output tap of switch will go to a solar battery charger. This is just in prep for an experiment; dunno if the Meanwell will work as input to the solar charger. If not, I won't need the switch.

I have an extra DC breaker but it's not double throw.
A relay sounds like a better idea.
But one with double throw and centre off?
Could use the DC breaker to provide the Off function I suppose.

OP:
would you most what you are trying to power? Please give make and model.

Use a Cooper Bussman switching DC breaker. Smallest would probably be 40 amp?

Switching breaker has contacts better designed to withstand repeatedly breaking under load.

Amps is amps. The voltage does not matter much unless you are taking about over 250V. A relay would be safer.

I think maybe you'd be well served to look into solid state relays for this sort of thing.

An example (that looks potentially suitable--no idea if this is the best brand or price out there).

Trying to increase the current capability of a switch by paralleling contacts is probably not a good idea. It's reasonable to expect that one of the contacts would generally switch a fraction of a second before the other, and so the slower switching one would end up breaking the full current anyhow. (It is also not recommended to assume that AC ratings are appropriate as DC ratings, particularly at higher voltage and current levels, as you apparently are already aware. Breaking high DC currents is a lot harder on a switch than breaking the same AC currents since with a DC load there are no momentary zero current crossings where any arc that may have started will break itself down.)

I would not switch that heavy of load. I would install a relay rated for 30 amps min., then install a switch to operate the relay.
You show wanting to switch a 700 watt load, at 12 volts that is nearly 60 amps.
That would require a relay of 100 amps to be on safe side. A relay like that would be one that lookslike the old Ford starter relays, but rated for continuous duty.