How to Change an Electrical Box From Screw-in Fuses to Breakers

Breaker boxes are the modern counterparts of fuse boxes.

The service panel in your house is a required safety component of the electrical system. Older panels use screw-in fuses with strips of metal designed to melt when the current heats them to a preset temperature. Once one of these fuses blows, it has to be replaced. Modern panels use circuit breakers that trip when the current passing through a solenoid produces enough magnetic force to open the circuit. These breakers are reusable. Fuses and breakers are not interchangeable, so if you want to replace one with another, you have to replace the whole panel.

Remove Fuse Box

Step 1 – Turn off the power to the fuse box. Call the power company to switch it off or hire an electrician to disconnect it at the electric meter.

Step 2 – Disconnect all the wires with a screwdriver and label the cables to identify them. Loosen the clamps in the side of the fuse box and pull out all the wires.

Step 3 – Disconnect the main power cables and pull them out of the box. Unbolt the box from the wall with a socket wrench and lift it off.

Installation

Step 1 – Bolt a new circuit breaker panel onto the wall from which you removed the fuse box. Knock out holes in the top or bottom of the panel for the main power leads with a screwdriver and hammer. Attach cable clamps to the hole by tightening the nuts on the clamps with channel-locking pliers. Feed the main power cables through the clamps and attach the red and black (hot) ones to the brass bus bars and the white (neutral) one to the silver bus bar.

Step 2 – Ground the panel. Pound a ground rod 8 feet into the earth and attach a 10-gauge bare copper ground wire to it with a grounding clamp. Run the wire to the panel and attach it to the main terminal on the ground bus. Make sure the neutral bus is in contact with the ground bus. You may have to tighten a screw on the neutral bus to do this.

Step 3 – Knock out enough holes in the sides and bottom of the panel to accommodate all the circuit cables. Attach cable clamps to the holes. Feed the cables through and tighten the clamps. You can feed as many cables through each hole as will fit.

Step 4 – Attach the white wire from each cable to a slot on the silver bus. Loosen the lug with a screwdriver, insert the end of the wire and tighten the lug. If the cables have a ground wire, attach each one to a slot on the ground bus.

Step 5 – Attach each black wire to a separate circuit breaker. Use a breaker with the same rating as the fuse to which the circuit was connected in the old fuse box. Loosen the lug on the bottom of the breaker. Insert the end of the wire and tighten the lug. Snap the breaker into an available slot on the hot bus. Label the circuit on the panel cover plate.

Step 6 – Connect the red and black wires of 220-volt circuits to separate terminals of a coupled breaker. Snap the breaker onto the hot bus. It will take two spaces, so make sure you have two adjacent ones available.

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