Hi, I'm an electrical engineer designing a schematic for an UL508A industrial control panel.

The control circuit will be fed from a 12V battery of a genset from the field. This supply to the control panel will need a disconnect switch (disconnect in every incoming supply). The problem is finding a switch suitable for 12Vdc, 20A. Most load switches do not have a DC rating.

I already have selected class cc fuseholders with fuses for overcurrent protection of the control circuit, but these cannot serve as disconnect switch according to UL508A.

I have also found a fused switch and a non-fused switch for PV applications, but these are too bulky for my application.

Now I noticed that according to UL508A overcurrent protection for control circuit with AC ratings can be used for DC up to 32 Vdc. Would this mean I can use a UL listed breaker or fuse switch rated for AC on 12Vdc?

 

Some switches and circuit breakers are explicitly rated for both AC and DC operation. You can consider choosing one of those.