Fuses safety basics

Although there’s a variety of fuses, most old residential systems use the glass, screw-in type called plug fuses. These fuses feature a narrow metal strip, visible through the glass, that quickly melts when too much current is starting to move through the circuit. Fuses are rated by amperage and cannot be reused after they burn out or “blow.” A fuse system generally is safe if it’s used according to its design. This means …

• Always using the correct size fuse.
• Being sure the fuse is screwed in tightly.
• Not listening to your old uncle Bob, who says you can replace a fuse with a Lincoln-head penny and call it good.

The glass of a blown-out fuse might look smoky, or more noticeably, the strip will be melted or separated. Before replacing it, you should turn off any electrical load that might have caused the overload.
Some electricians recommend that you also turn off the main switch to the fuse box before removing and replacing the old fuse. Whatever you do, be sure to keep one hand behind your back or in your pocket! You don’t want both hands near the box, because if both accidentally touch it, you can become part of a circuit and electrocute yourself.