Nothing to see here, just kneeling in front of the electric outlet appreciating Edison’s miracle!
– Homer Simpson
Remember the remodel? With the homeowner electrical permit? Well, the updated electrical code requires arc-fault protection, which is different from the more familiar ground-fault protection. Ground-fault interrupters deal with electricity that runs to an unintended ground, like someone standing in a puddle wielding a hair dryer.
Usually, arc faults are less immediately freaky. They occur when current jumps between conductors. For instance, a wire nut might not be on tightly enough, so the current arcs between the wires a tiny distance. Arcs are hot (duh) and can start fires, but they don’t automatically trip a regular breaker. To comply with the electrical code, we needed to install an arc-fault circuit breaker on every new and modified circuit.
THOSE OF YOU WHO UNDERSTAND HOW TO WORK IN A BREAKER PANEL WITHOUT FRYING YOURSELF, READ ON.
For a standard circuit, the hot/black wire from the line attaches to the breaker, while the neutral/white wire and the ground go to the neutral bus and ground bar respectively. (Stop reading if this is news to you!) The arc-fault interrupting breaker is connected to both the hot wire and the neutral wire. Then, a curly white wire extends from the breaker to the neutral bus. Dad taught me to keep panel wires neat, and the curliness is a little untidy, but that’s incidental.
Despite unsightly curliness, most of the circuits in question worked fine with the new breakers. But on the last modified circuit:
Installed. Turned on. Flipped. Reset. Flipped. Reset. Flipped. In denial, I bought a replacement breaker. Same result. So…there was an arc fault.
Finding and fixing the fault involves checking every connection on the circuit. Assuming there wasn’t a hole in the wiring somewhere (from a stray nail, for instance), there were 26 potential spots to check.
But it wasn’t that bad once we thought about it strategically.
- Divide and Conquer: If the circuit branches at a junction box, disconnect everything and then try each sub-branch separately. If one section doesn’t trip the breaker after you try everything under load, then that part’s ok. We eliminated about 80% of the connections this way.
- Likely Suspects: If the fault is in the connections, then it’s probably in a wire nut rather than at a switch or receptacle. Switches and receptacles should have screwed-down connections, so prioritize checking junction boxes, light fixtures, and pigtails. Make sure that each connection is solid and that the wire nut is the right size.
- Even More Likely Suspects: If you are still reading despite my many disclaimers, you know that many light fixtures have small-gauge stranded wires. They tend to go all frayed when connected with a single larger wire with a wire nut. To combat the problem, strip the fixture wire so it’s a little longer than the ends on the solid wire, then line the insulation up and spin the wires together with pliers before applying the wire nut.
We found two problems. A junction box (pre-existing) had a loose wire nut, and a sconce light (installed by me) had a sub-par connection involving stranded wire. These worked fine with a regular breaker, which doesn’t sense these small faults.
The hunt was time-consuming, but doable (especially working together). If checking connections hadn’t worked, though, we would have called an electrician in a hot second (pun!). We don’t have the equipment or knowledge (or, in my case, the fortitude) to isolate an arc fault inside the wall.
Next: closing out the electrical permit!