How to Turn Off Power at the Fuse Box in Older Homes

When you're preparing for any kind of electrical work, the first (and most important) step is to turn off the power. Most modern homes have circuit breakers, but if your home is older, it may still rely on fuses. So if your home has a fuse box, follow these step-by-step instructions for turning off the power while keeping you and your family safe.

How to Turn Off an Individual Fuse

At your fuse box, partially shut off power by unscrewing and removing a fuse. Test the device to make sure the power is off before doing any work. If a fuse has blown, replace it with a new one.

How to Turn Off Power to the Whole House

To turn off power to the entire house, pull out the main fuse block, which looks like a rectangular block with a handle. It is usually located at the top of the panel. Tug hard and straight out on the handle. Use caution; the metal parts may be hot.

How to Check Fuses

A main block or 240-volt circuit may have a fuse block that has cartridge fuses inside. Remove an individual cartridge fuse by pulling it out from the holders. Test the fuse and, if necessary, replace it.

What If a Fuse Blows Frequently?

When a fuse blows frequently, it's tempting to replace it with one of a greater amperage. This is dangerous—house wires could burn up before the fuse blows. Instead, remove some of the load from the circuit.

The wire gauge in the circuit determines how large a fuse or circuit breaker it can have. A 15-amp circuit should have 14-gauge or larger wire; a 20-amp circuit, 12-gauge or larger; and a 30-amp circuit, 10-gauge or larger.

Checking the wire gauge is easy if you have nonmetallic cable running into the box. Examine the sheathing for a stamped or printed identification, which includes the gauge. With armored sheathing or conduit, open a receptacle on the circuit. Check the insulation on the wires for a gauge marking or compare it with a wire of known gauge.