Reducing the space in my garage.

[Clive S]

I think it would be good if you put a schematic up exactly how you have wired it. Is that a RCD on the main fuse? If you have blown the 13A fuse you may have an earth fault. Is there a reason you are using an SCR in the circuit? What type of MCB have you used ie B type etc? ..Clive

[Jonathan]

As Clive said, a diagram would be best. However I'll risk guessing - if you're connecting the transformer to the mains without a soft start socket, then the inrush current from charging the capacitors may be too high. Also, are those automotive type blade fuses and are they used on the mains or 70V circuit? If so you shouldn't use that type there as they're only rated for 12-24V. To be fair the fuse still seems to have worked... but that's maybe not the point!

[routercnc]

I'm not an expert on electrics but I wouldn't use the automotive fuse on mains AC. Either MCB or DIN mounted glass fuse holder designed for AC would be my choice.

I did a lot of looking into fuses for the DC side and concluded that it was ok to use a 5A 12V automotive blade fuse at 5A 70V because the fuse would blow at a certain power which is the current squared times the fuse resistance. The voltage didn't come into it until the fuse blew and the gap created needed to be big enough to prevent an arc ( therefore still allowing current through).

That was where I got to it anyway. I also saw Irving use one ( with a disclaimer)!

Clive - you wrote SCR did you mean SSR as in solid state relay?

[Rich]

Thank you all, I can see I've made a mistake by using a spade as a primary fuse. The intention was to use a slow blow fuse, per the thread. I have one ... but because it wasn't on the purchase list, it dropped off the build list.

I will draw a schematic and add a parts list, that will help clarify my issue and hopefully put me back on track.