Nonworking light begins working after lightning strike

Question

We've had an electrical issue in one room where the outlets on two walls as well as the overhead light had quit working. Last night, we had a nearby lightning strike. It was so close that there was no time between the lightning and the thunder. This morning the light was on. The outlets are now working again, too. Do we need to worry about a fire starting along the circuits to that light or those outlets?

Answer 1

When part of a circuit stops working, such as lights and receptacles in one room but not others, that typically means that there is one bad connection. That can be a loose wire nut, a bad backstab connection, a wire coming off a screw or almost anything else. But most of the time it will be some deliberate connection that was never quite 100% perfect and over time separated to the point where it no longer works. In some cases the connection will be intermittent - e.g., as wires heat up and expand they will start working again, or perhaps physical movement (hit the wall near a receptacle) will make a difference.

If the problem is anything short (pun intended) of a wire literally falling out of a connection, it is possible that a very large surge, such as a nearby lightning strike, could heat up the wires enough to "fix" the problem. But that "fix" may be only temporary and may in fact hide a serious problem.

• Check all other circuits for problems. A surge in one circuit caused by an external factor (lightning) would generally affect all circuits in the house to some degree. If you find problems such as electronic devices that no longer work properly, lots of light bulbs burned out, or any other unusual electrical problems then a full (i.e., professional) electrical system checkup may be warranted.

• Check every junction - receptacle, light switch, light fixture box, etc. - on the specific problem circuit. Look for any loose wires, backstab wires (which should be moved to the side screws), evidence of arcing (e.g., charred insulation) or other problems. Hopefully you will find one specific junction with problems (meaning you found the problem) and solve the original mystery.

• If any receptacle or switch shows evidence of problems, replace it. Good quality receptacles and switches (not counting smart switches, GFCI receptacles, etc.) usually only cost a few $ (< $5), and are much better quality than the cheap receptacles and switches (< $1). In particular, look for screw-to-clamp connections where the wires go straight in, instead of having to make a curved hook. In any case, do not use single-use backstab connections ("quick wire" or similar name) where you push in a wire without having to tighten a screw - those are very unreliable.

Answer 2

Was the lightning strike really loud? Like loud enough to make the house shake? It's possible that you had a loose connection at one of your switches or outlets and the sound vibration was enough to re-connect the loose connection. (This would have nothing to do with an electrical surge -- it's strictly mechanical.)

Here's what you can do: turn on the light that was previously non-working. Go to each switch and outlet that was formerly non-working and pound on the wall right near the switch or outlet really hard while you watch the light. Not hard enough to break the sheetrock, but hard enough to strongly vibrate the wall. If the light flickers or turns off, you've found the switch or outlet with the loose connection, and you can then follow manassehkatz's suggestion on repair or replacement of that device.