What's a fuse lamp?
It is a requirement in most modern series wired lighting sets.
Most lmodern series wired lights use permanent contact bulbs, these are designed to fail short circuit at end of life in order that the remaining lamps in a series chain will remain lit.
Unfortunatly, the failure of several permanent contact lamps leads to rapid failure of the rest, and a virtual short circuit with risk of fire.
Therefore in many countries it is a requirement that series wired lighting sets with permanent contact lamps incorporate a fuse bulb. This is of a slightly lower current than the others and does NOT have a permanent contact device.
Any excess current will therefore blow this lamp and cut off the current before any serious harm is done.
The fuse lamp should be identified by having an opaque white tip, and if screw based by having a nickel plated base rather than brass.
A failed fuse lamp should only be replaced with a similar one.
If a permanent contact lamp is used instead of the fuse lamp, then the set will still work but be less safe. I would not worry for a brief test, but for long term or unattended use, no way.
Older series wired lighting sets did not use fuse lamps and the therefore the failure of any lamp put the whole string out. No big deal with say 8 or 12 lamps, but a problem with a long string.
In Canada and the USA , many lighting sets use line voltage lamps, not series connections.
