File:Hazardous Homemade Pyrotechnic Flash Pot.jpg

English: This is an example of a simple homemade pyrotechnic flashpot constructed by amateurs who know just enough about electrical wiring to get themselves into a very hazardous situation.

Modified fuses are used as ignitors, with flash powder poured inside the fuse around the fusible link. Direct-shorting the fuse causes the link to melt instantly and ignite the powder.

One of the biggest problems with this device is that it does not include any pilot lights, and so in a dark room it may be difficult to know if a socket is powered or not. Screwing a fuse loaded with flash powder into a live socket will cause it to blow up in the face of the stage hand, severely burning and potentially blinding them.

Even screwing an "unloaded" fuse without powder into a live socket can suddenly eject a vaporized cloud of metal slag from the fusible link up into the face of the stage hand.

Further, since this is assembled by amateurs, grounding may not be observed, hot/neutral polarity may be reversed, and since this circuit has no electrical isolation transformer, the socket shell can pose an electrocution hazard to anyone handling the fixture or the fuses.

Attempting to use fuses 10 amps or larger as an ignitor can cause much larger 100 amp to 600 amp fuses and breakers to trip, causing widespread building disruption. This occurs because protection is designed to trip instantly if a sufficient amount of current passes in a very short period. Several hundred amps can potentially pass through a small direct-shorted fuse for a few milliseconds before it melts or vaporizes.

This is an all-around disaster waiting to happen, and if a fire marshall were to see this in use, the stage/venue could very well be closed for unsafe operating conditions.