Purpose of fuse in a 12vac halogen lamp plugged into 120vac outlet


Joined Nov 6, 2012
It's not to protect the Bulb.

Virtually all Mains-Powered devices will have some sort of Fuse,
or sometimes, an Electronic-Circuit to protect against Over-Current-Faults.

So, generally speaking, it is for Fire-Safety


Joined Aug 7, 2020
In case some idiot installs a halogen lamp of greater power than the transformer can supply.
Also, halogen lamps mounted base-down have a nasty habit of developing an internal short circuit when the filament finally breaks.


Joined Jan 23, 2018
I presume that the fuse is in the mains connection to a transformer powering the 12 volt lamp. As already stated, the fuse is intended to prevent a fire from overheating in the case of some fault allowing more than the design current to flow in the mains connection. In my area normal mains connections are protected at either 15 amps or 20 amps, while the cord connecting to most devices will greatly overheat at some current less than that. Thus the fuse is provided to limit the current to a value that will not cause an overheating fire.