Electronic – Are fuse wires in air tightly sealed heat shrink tubes safe

fusesheatwire

i've seen a few Videos now, where people use fuse wire as single cell protection layer for parallel battery packs to protect against catastrophic failure due short circuit of a defective cell.

Often these battery packs are sealed with heat shrink tube resulting in these fuse wires to be (more or less) air tightly sealed.

Is that safe? Will those trigger even without air?
My understanding is, that fuse wires will act as a circuit breaker by simply burning through, which seems difficult without air?

Thanks for your time.

Best Answer

Absence of air is good for a fuse. The fuse opens by melting. Air, and especially the contaminants in it in industrial regions, can sometimes degrade a warm fuse wire over time.