Tinned copper fuse wire

[PJL]

I bought an old 22SWG reel from a carboot. Does the 'fuse' mean it has some special properties? My best guess is this means it was designed for electrical use and therefore should have uniform resistance and be low on defects?

[kalee20]

Very much doubt it!

Electrical grade wire should be pretty uniform in diameter and purity anyway.

[broadgage]

Agree, tinned copper wire for use as fuse wire was nothing special, just the same stuff as used for other purposes.

[Herald1360]

Though "fuse wire" also looked like tinned copper but wasn't- it was thicker for the same fuse rating. Might be worth measuring its resistance in case it isn't really tinned copper.

[pmmunro]

The last page of this article has a table of fuse ratings and wire sizes. http://electrical.theiet.org/wiring-...s.cfm?type=pdf

PMM

[broadgage]

For a normal running current of about 5 amps and upwards, fuse wire usually consisted of standard tinned copper wire, nothing special was used.

For currents less than about 5 amps, special fuse wire was often used, consisting of a lead alloy. The greater resistance and lower melting point of this alloy meant that thicker wire was needed, a decided advantage as copper wire to fuse at say 2 amps would be too thin to easily handle.

special fuse wire was often used, consisting of a lead alloy

Not a good idea if it was clamped by a screw (the lead just squishes, no springing back), just why you don't tin wires before putting them in a terminal.

[kalee20]

Absolutely!

Though there's no reason why a higher-resistance alloy couldn't be used (of suitable mechanical properties so it's compatible with screw clamping), so as to allow chunkier diameter wires for low-current fusing.

[emeritus]

Here's a table of the fusing currents for various types of fuse wire from the 1893 GEC catalogue. Although the table gives fusing currents for Copper and Iron wires, the fuse wire links sold by GEC at that time for use with their fuse holders were only either Tin or Lead. They were in the form of pre-cut lengths of wire terminated in fork terminals, which would have avoided problems with clamping the soft wires of the fuse wires themselves.

The volume of the 1911 GEC catalogue that I have only lists tinned copper wire for fuses, and only includes fuse wires rated for 15A and higher.