A Penny in a Fuse Socket

Did you ever put a penny in a fuse socket? If you did, you were trying to solve an overloading problem, and created a fire hazard in the process. Many of us think of fuses and circuit breakers as devices that protect our appliances and other electrical devices. What a fuse or circuit breaker actually protects is the wiring that supplies power to those things.

Wire is called a "current carrying conductor." It carries electrical current to lights, TV sets, washing machines and a host of other things. Like anything else, it only has the capacity to carry so much of a load. Just like a 1-inch line will not safely carry as heavy a load as a 2-inch line, a smaller conductor will not safely carry as much current as a larger one.

An example of pushing more current through a wire than it can safely carry is the wiring inside the conventional toaster. An excessive current is pushed through those wires in order to intentionally overheat them. Due to the toaster's housing, and because of the way the wiring is mounted, that "overheating" situation is safe. It toasts our bread and we are happy.

What happens if the wiring behind the salon seating on our boat gets that hot. Are we still happy? I don't think so. Our boat will probably be on fire as a result of the overheated wiring being in against wood, fabrics, etc. How can something like this happen? There are a few possibilities.

First, we could have overloaded our wiring by adding equipment to an existing circuit. If a circuit has a 5 or 10 amp breaker on it to protect that wiring, and we add enough equipment to the circuit to draw 20 or 25 amps, the breaker will trip. If we replace it with a larger breaker, the larger breaker probably will not trip. However, we will be pushing over twice the current through our wiring than it is rated for. That wiring will heat up!

Another scenario is if we are using a "common neutral" wire for a few circuits. In this case, we may have three circuits properly fused for 10 amps each. If the second wire for each circuit is used in common with all three circuits, it may carry up to 30 amps without any of the three 10 amp breakers tripping. If the neutral wire is rated for 10 amps like the other three wires, it will be carrying three times as much as it is rated for.

Some people believe that while overloading a 110 volt or 220 volt circuit is very dangerous, a 12-volt circuit is not. After all, it's only 12 volts. Well, if you have any doubt, experiment with your car's the cigarette lighter. Push it in, and when it pops out, put it on the end of your tongue. What do you think 12 volts can do now?

The bottom line to all of this is to replace all fuses and circuit breakers with the proper size, and to have qualified personnel do your wiring. It's easy to be "electrically safe" aboard your vessel. It's just a matter of paying attention!

Until next time, I wish you clear skies, fair winds, and calm seas!