On Thursday, July 11, 2019 at 10:44:25 AM UTC-4, Bob Engelhardt wrote:
On 7/10/2019 10:06 PM, Jeff Liebermann wrote:
I couldn't find anything similar, partly because you didn't supply the
maker and model number of the variac.

It's a Ward Leonard (no model number) - yeah, I never heard of them
either and I didn't find anything on the web. They did make variacs for
theatrical lighting, so that's probably where this came from.

The lead colored material is probably zinc steel. Try checking with a
magnet.

It's non magnetic. Following your powerstream lead, I'm guessing it's
tin, or lead-tin.

...
Therefore, the cross sectional area is:
0.063 * 0.033 = 0.0021 sq-in = 2700 circular-mils

The bridge measures .017 x .068 in; 1472 circ mils (.038 equiv diam)

...
https://www.powerstream.com/wire-fusing-currents.htm
shows that #16 AWG will fuse at: ...

AWG 18 is .0403 diam & tin fusing current is 13A. Which is considerably
less than the 20A that the variac is rated for resistive.

I doubt that you're going to find a replacement fuse. ...
Or, you could just replace it with an external 35A cartridge fuse.

Yeah, I put in a piece of 14ga copper & will use an external fuse. For
now, I'll just rely on the 15A breaker that it's plugged into.

The confusing thing to me was how inconvenient this fuse's replacement
was. The mounting block had to be removed (2 screws) & the fuse was
held by another 2 screws, each with a sleeve, flat washer, lock washer,
& nut. What were they thinking?

Thanks for your in-depth reply.

If it was made for stage lighting, the panel would have a fuse per fader (Variac).

Stage crews would replace blown fuses with anything that would restore the lights, so a hidden fuse prevented a fire from an overloaded fader. The early ones I used in high school and working on school equipment used Edison based screw in fuses. You would find 30A in place of 15 or 20A, and dead faders.