Back in the old days, homes had fuse boxes. Today, of course, any new house is built with a circuit breaker panel and many older homes have been upgraded at one time or another. However, the fuse is a much more interesting analogy for the monetary system.
When a fuse burned out, it was protecting you from the risk of a house fire. Each circuit is designed for only so much current. The problem is that higher current causes more heat, and it can start a fire. So they put fuses in, which burn out before the wire gets hot enough to be dangerous.