How to Understand Electricity in a Fuse Box
- 1). Open the panel to your fuse box and identify whether you have fuses or circuit breakers.
Circuit breakers have switches that trip when they are overloaded. You can reset them. If there are no switches, then you have fuses. Fuses blow if the circuit is overloaded. You must replace blown ones with a new fuse. Both breakers and fuses limit how much current (amps) can flow in a circuit. Fifteen- or 20-amp breakers are most common, but you may have one or two 30-amp breakers for circuits that power large appliances like your heating and cooling system. - 2). Look at the thin metal rod running behind each column of breakers (if you have an open slot to see through). This is the hot bus bar. Power enters the home from the outside of the panel and runs into this/these bar(s). Sometimes there is a main breaker that can remove power from the hot bus bar, but this is not always required. Circuit breakers or fuses clip into the hot bus bar to receive power.
- 3). Look at the other side of a breaker. There should be a black wire screwed in there. It is live electricity going to power the circuit.
- 4). Follow the black wire up to see it has accompanying white (neutral) and copper (ground) wires. They both screw into the neutral bus bar, which is connected to a long metal pole stuck deep into the ground. Under normal conditions, power runs through every electric device in the circuit and returns to ground through the white wire. When there is a short circuit somewhere, the fault current runs in a safer, faster, less-resistive path through the copper grounding wire to ground. Also, the breaker will trip or the fuse will blow.
