Hi,

I'm fed up of not getting a decent answer on google. So many people say different things.

Can I use a 240vac fuse in a 24vdc circuit. I know some fuses are compatible with both AC and DC, and if so the DC rated voltage is usually a fraction of the AC rating. Also, arcing has an effect on a DC circuit.

I'm wanting to fuse a 24vdc circuit at 8amp.
Alternatively, could I use a 12vdc spade fuse at 8amp? Or would I need a 16amp?

Thanks,

 

hi Jim,
A regular fuse is based on its 'fusing' current, ie: the current at which the wire melts.
You can get slow blow or fast blow fuses, all that means is how fast the wire melts and the circuit is opened.
Fast for electronics, slow for general use.
A 8Amp fuse will fuse at just over 8Amps. on 12V or 230V

E

 

Can I use a 240vac fuse in a 24vdc

In this case, I would say Yes you can use it. In general, the voltage rating on the fuse is there to prevent arcing after the fuse is blown.
And of course, it is much "harder" to prevent arcing at DC circuit than AC. But additional details should be found on the fuse datasheet.

 

Does the fuse also carry a DC rating?
If not then the answer is no it can't be used... (will it work.. Sure..) but if its being used in a DC circuit and only has an AC rating then its being used outside of its approval rating and would be something that would need to be addressed if this was a professional application.

BTW.. Its not really a "240vac" fuse.. Its likely rated higher than that.. Fuses are typically rated to the maximum voltage they have been approved for and not a particular voltage..
So a typical fuse would be rated to something like 600vac and can be used in any AC circuit of 600V or less.

 

Short answer is YES, the fuse will protect the 24 volt wiring if it is a 250 volt rated fuse.. And the opening time will be reasonable, since you are running with less tha 10% od the rated clearing voltage. Experience verifies this.