Well, sometimes it happens...get a little clumsy with a tool and short a power lead to ground. In this case the wire was protected at the source with a fusible link, which did its duty.
This one is an 18 ga wire, so the link is the usual 4 sizes smaller, i.e. 22 ga. The fiberglass tube sheath is from a B&C kit. I make mine with bare crimp terminals, so the assembly is more compact than one made with red AMP splices.
The tube shows only a small burn mark...
...but the trusty Fluke says it's open, so let's do some surgery for the curious. The crimp splices add mass to the ends of the 22 ga, so as we might predict, it burns open right in the middle:
This one is an 18 ga wire, so the link is the usual 4 sizes smaller, i.e. 22 ga. The fiberglass tube sheath is from a B&C kit. I make mine with bare crimp terminals, so the assembly is more compact than one made with red AMP splices.
The tube shows only a small burn mark...
...but the trusty Fluke says it's open, so let's do some surgery for the curious. The crimp splices add mass to the ends of the 22 ga, so as we might predict, it burns open right in the middle: