Did a lightning strike kill my lightswitch?

Several days ago, we had thunderstorms come through the area over a period of a few days. Just for an example, let’s say we had storms last Monday, Tuesday, and Wednesday. On Monday, we had a very close lightning strike. There was maybe 1/10th of a second between the flash and the boom, perhaps less. Just enough to notice they were not simultaneous. No problems with anything.

On Tuesday, we had some more storms. The lights blinked a few times, during the storm, but the power never went out. No problems with anything.

On Wednesday, we had another storm with a close lightning strike, but not as close as the one on Monday. There was close to a full second between the flash and the boom. The kitchen light (4 tube fluorescent) went out. At first, I though we’d lost power, but all the other lights were working. I tried the switch, but no luck. No light. So, I said, it’s probably the ballast, I’ll have to go to Lowe’s and get a new one. On Thursday, I found that the kitchen light was on a 3-way switch, with one in the dining room. If I turned the kitchen switch to the up position, the dining room switch would turn the light on and off. If the kitchen switch was in the down position, the dining room switch did not work (no light).

So, I knew the ballast was OK, but the kitchen 3-way switch was bad. On Friday, I went to Lowe’s, got a new 3-way switch, installed it and we are all OK now.

But, why did the lightning strike kill the switch. And, why that switch and nothing else in the house? As one additional bit of perhaps unrelated information, when I replaced the switch, I discovered that the ground wire was not connected. There was a ground in the switch box, but it was never connected to the switch. The switch had paint on it from when the kitchen was painted, and I broke that paint when I removed it, so I know the electrician who wired the house did not connect the ground on that switch (or that switch was not installed by an electrician, but wouldn’t installing the light switches be part of wiring a new house?).

Anyway, I connected the ground when I replaced the switch and all is fine, now. But, why did the switch fail?

Curious to this as well. We got hammered by a lightening strike 2 years ago. Along with some appliances, I noticed that many, 3 way switches were acting up (tripping breakers when flipped on a certain way). Ended up replacing the ones that were troublesome, no big deal. Just odd it was only 3 way switches.

It may be just coincidence, or the light switch was about to fail and a tiny surge blew it out.

My experience with a recent close lightning strike was the same as joe.russell’s … half the light bulbs exploded, all the breakers tripped and the Telephone Network Interface box blew up sending shards twenty to thirty feet away …

… and the tree was in even worster shape …

A direct lightning strike far down the street may be a direct strike incoming to all household appliances. It is electricity. If an outgoing path also does not exist, then no current and no damage.

Once all but invited inside, then lightning goes hunting for earth destructively via one or some paths. In your case, one path would have included that switch. Incoming on AC mains. Somehow it found a best path to earth destructively via that switch.

First that current is everywhere and simultaneous in a path from cloud to earthborne charges maybe miles from a house. Generally only one item in that path fails. Voltage increases as necessary to blow through anything that might foolishly try to stop it. Possible that a switch’s open contacts were a best path to earth and to charges that are miles distant. Damage because a millimeters gap between switch contacts tried to stop that current.

Incoming on AC mains. Somehow found an outgoing path to earth destructively via a switch. Since that was a best path, then robust protection in other appliances was not overwhelmed.

Damage was due to no properly earthed ‘whole house’ solution with THE most critical item found in every protection system: single point earth ground. Never confuse a safety ground wire (that you connected) with earth ground. Effectiveness is determined by the quality of and a low impedance (ie less than 10 feet) connection to earth.

Above describes a ‘secondary’ protection layer. Also critical is your ‘primary’ protection layer as demonstrated by pictures (not text) after a label “open vertical grounds” in http://www.fpl-fraud.com/
If that primary protection layer is missing, then lightning can short high voltage primary wires (ie 4000 or 13000 volts) directly into household wiring. Lightning does not have energy necessary to explode bulbs or trip breakers. But a ‘follow through’ current from the AC utility does. If that earth ground was not compromised by copper thieves, that ‘follow through’ current should not exist.

Damage occurs when that a victim is a best connection from cloud to earth. Best protection exists if that current is connected to earth BEFORE entering a structure. This well proven solution costs about $1 per protected appliance. So that even wall switches are protected.

Nothing inside can ‘block’ or ‘absorb’ a surge. Protection is always about no reason for a current to be inside - hunting for earth destructively via appliances - or in your case a switch.

OK. I performed an autopsy on the failed switch. Examination of the switch revealed that it had three pieces held together by two rivets, which I will call the mounting plate, the top plate, and the body. The mounting plate is made of plated steel (galvanized, I think), while the top plate and body appear to be a phenolic plastic (Bakelite, perhaps?).

First, it is obvious that the ground is attached to the mounting plate and electrically insulated from the rest of the switch. This suggests to me that the lack of the ground connection did not contribute to the demise of the switch. All the ground really does is make sure if a live wire should contact the mounting plate, it would short directly to ground and trip the circuit breaker.

When I removed the top plate to expose the inside of the body, I found the body to be filled with what I’ll call “Fluff”. I suspect the fluff is bits of thermal insulation that had been drawn into the body by the climate control air handling system. The house is a little over 20 years old and well sealed at the windows and doors. I suspect the air handling system leaks slightly in the attic, so when it is running, the interior of the house is at a slightly negative pressure compared to the attic. This draws bits of attic insulation into the interior walls and through openings in those walls, such as a light switch. As the switch has those “push in” connectors on the back, there are many openings on the back for those bits to enter the switch over the years. There were arc burns on both sets of contacts (this is a 3-way switch), but as these were on both sets of contacts and one set of contacts was still functional, I do not attribute the failure to the arc burns.

So, my suspicion is that the concussion from the thunder (the thunder clap was loud and shook the house) briefly caused the closed contacts to separate, and forced a bit of the fluff to get between the contacts, breaking the circuit. That is, the failure was mechanical, not electrical. After removing the fluff and reassembling the switch, it checks out with my ohm-meter and I suspect that if I used tiny screws with nuts in place of the rivets I drilled-out, the switch would perform as new.

The sad fact is, however, that I’d probably have to pay more for the screws and nuts than I paid for the replacement switch so it’s off to the landfill for the switch.

Thank you for letting us know. I thought that if it was the lightning, it would have melted and possibly started a fire.

I’m a bit confused: you didn’t even know about the dining room three-way switch until you investigated? If so, then you don’t really know when it failed. Maybe Wednesday was the first day since it failed that someone flipped the dining room switch to the ‘off’ position.

No, it failed at the same time the thunder clap occurred. I was in the kitchen and nobody was in the dining room; I saw the flash and less than one second later we heard the thunder and the light went out. The kitchen switch is what we normally use to control the light, so we tried that switch and it did not work.

It was the next day that I noticed the switch in the dining room and thought to investigate if it would work. I had known about it, but since we usually use the kitchen switch, we didn’t think of checking it the day before. I had assumed the ballast was bad since the breaker hadn’t blown and nothing else in the house experienced a problem.