Why that boom you heard isn’t a “transformer blowing.”

During bad weather, many folks will hear electrical booms in their area and blame it on a “transformer blowing.”

The truth is that transformers are expensive, so the power companies protect them with equipment called “cut-out fuses.” In a lot of cases where a branch has brushed a power line, these fuses will blow and cut power to a street. If the branch falls away and the line isn’t damaged, a lineman can quickly restore power just by resetting the fuse using a long pole.

So now you know.

In electrical distribution, a fuse cutout or cut-out fuse is a combination of a fuse and a switch, used in primary overhead feeder lines and taps to protect distribution transformers from current surges and overloads. An overcurrent caused by a fault in the transformer or customer circuit will cause the fuse to melt, disconnecting the transformer from the line. It can also be opened manually by utility linemen standing on the ground and using a long insulating stick called a "hot stick".

via Fuse cutout – Wikipedia, the free encyclopedia.