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I've got a design that I'm working on which requires a number of separate 250V fuses (5 off) on a PCB. Since I'm trying to make the PCB as compact as possible, standard 5x20mm fuses aren't really suitable.

I've seen that both Littelfuse and Schurter have 250V surface mount fuses available, but these don't appear to have PCB fuse holders rated at 250V+, and I'd really rather use a fuse holder in this application (both for the ease of fuse replacement, and to shroud the 'live' terminals just slightly more). I originally fell into the trap of designing around mini blade fuses, since there were plenty of 500V rated mini blade fuse holders... but it fell apart when I then went to BOM both fuses and fuse holders, and found that the fuses themselves maxed out at like ~50V...

Is there a typical way that others approach mains voltage fusing on a PCB to keep things compact?

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  • \$\begingroup\$ not quite sure what it is that you actually want - on one hand you want a fuse holder, on the other you want things to be very compact. Considering necessary isolation distances, I don't think you'll get a lot smaller than the usual melting type 5×20 mm fuses. Also, what use is in-field replaceability if the thing you're replacing is tiny enough to require full disassembly on a level table? \$\endgroup\$
    – Marcus Müller
    Commented Mar 28, 2021 at 10:40
  • \$\begingroup\$ maybe the solution is to integrate the fuses into the connectors for your 250V or in the cables going there – but I don't know your overall product. \$\endgroup\$
    – Marcus Müller
    Commented Mar 28, 2021 at 10:41
  • \$\begingroup\$ The Littelfuse NANO fuses do go up at 250Vac (littelfuse.com/~/media/electronics/datasheets/fuses/…) in a 10mmx4mm package. So I guess I was hoping for a 12mmx6mm fuse holder. \$\endgroup\$
    – BevanWeiss
    Commented Mar 28, 2021 at 11:47
  • \$\begingroup\$ The compact sizing is more around the PCB mounting position, there's not all that much room, and a smaller PCB is still nicer. I had considered inline fuse holders, but it's screw terminals on the way out, so no guarantee that a given pair of wires connected will be fused correctly. \$\endgroup\$
    – BevanWeiss
    Commented Mar 28, 2021 at 11:50
  • \$\begingroup\$ It's looking like something similar to a TE5 (littelfuse.com/~/media/electronics/datasheets/fuses/…) might do the job... I could use the 562 / 564 fuse holder for it, which looks like quite a nice compact solution. \$\endgroup\$
    – BevanWeiss
    Commented Mar 28, 2021 at 12:00

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