Big Fuses

I have in my hand the biggest fuse I've ever touched, and the second biggest I've ever seen. A Ferraz Shawmut A50QS150-4, 150A at 500V.

150A might sound a little low considering I have a 280A controller, but my battery will struggle to provide all of that, and these fuses last a surprisingly long time at currents above their rating. In fact the fuse curves suggest the fuse will take 280A for about 100 seconds. At 500A it ought to take about 4 seconds to blow while the next largest size would take 12. Hopefully I won't blow it going up a hill.

The white outer jacket appears to be many layers of a fiberglass type material. I believe there is a special material (possibly more commonly known as sand?) inside which will smother the arc when the fuse blows. All the special materials in the world do no good if they're spread all over the place, so the jacket needs to be strong enough to prevent the fuse from exploding. The end pieces are pinned into the jacket to prevent them popping out.

(The biggest fuses I've seen in person were in a diesel electric train.)