Circuit Breakers & Fuses
Breakers and fuses protect the wiring from carrying more current than it can handle. When one trips or blows, it’s telling you something is wrong: an overload, a short circuit or a ground fault. Resetting it over and over, or replacing it with a bigger one, invites a fire or a shock.
- All workers
- Maintenance
- Homeowners
Photo: panelboard with a clear, typed circuit directory and one breaker in the tripped position
Types of protection
| Device | Protects against |
|---|---|
| Standard (thermal-magnetic) breaker | Overloads and short circuits; protects wires and equipment |
| Fuse | Overloads and short circuits; must be replaced after it blows |
| GFCI breaker or receptacle | Ground faults that could shock a person (trips at about 5 mA) |
| AFCI breaker | Arcing faults in wiring that could start a fire |
| Ground-fault protection of equipment (GFPE) | Ground faults that could damage large equipment; not for people |
Standard breakers and fuses protect wiring and equipment, but they don’t trip fast enough to protect you from a shock. That’s the GFCI’s job. See GFCIs.
When a breaker trips
- Find out why before resetting: unplug or turn off loads on that circuit, and look for damaged cords, wet equipment or a burning smell.
- Reset once, after checking. Stand to the side of the panel, and turn your face away.
- If it trips again, stop. OSHA prohibits repeatedly resetting a circuit until it’s determined that the equipment and circuit can be safely energized. Call a qualified electrician.
- Don’t reset if the panel is damaged, wet, hot, smoking or making noise.
Never
- Replace a breaker or fuse with a larger size to stop trips
- Use a penny, foil, wire or a slug in place of a fuse
- Tape or tie a breaker in the on position
- Remove a GFCI because it “keeps tripping”
- Open the panel cover (dead front) unless you’re qualified
Labeling and access
- Each circuit in a panel should be clearly and accurately labeled so the right breaker can be shut off fast in an emergency and for lockout.
- Keep at least 3 feet of clear working space in front of panels. See Panel Clearance.
- Fill empty breaker spaces with blanks; open holes expose live parts.
- Turning a breaker off is not lockout. For work on equipment, use a breaker lockout device and follow your lockout procedure. See Lockout/Tagout.
Standards & references
- 29 CFR 1910.334(b)(2): Reclosing circuits after protective device operation
- 29 CFR 1910.303: Electrical general requirements, including identification of disconnects
- See also: Electrical Basics · National Electrical Code
Last updated: