A lightning strike can damage wiring in a building. Specifically it can damage the insulation on the conductors, resulting in arcing and fire, either immediately or some time after the strike. I've seen insulation testing conducted after such a strike. This involves opening each breaker, disconnecting every load, and putting a voltage on the circuit to see if the insulation breaks down. For a structure of any size, this can be very time-consuming.

I can imagine an alternative: simply replace all breakers in the building with arc-fault interrupt breakers. If any arcing is happening, or starts after the fact, the breakers will trip and prevent a fire, and give a strong indicator of what circuit the damage is on. It almost certainly costs less than insulation testing every conductor, and while it's not the same kind of testing, it's a very effective test every second for the rest of the life of the structure. Plus it helps bring the building up to code, especially if you install breakers with GFCI capability as well.

Is there a reason this would be a bad idea, from a technical or safety standpoint?


An arc fault circuit interrupter will reduce the probability that an arc fault event will result in a fire. It does not guarantee that arc fault events will not cause a fire, nor will it protect against all other kinds of equipment damage.

Further, one advantage of doing the high-voltage test is that it ensures that if damage occurs while the property is owned by someone who has insurance, responsibility for repairs can get properly assigned to that insurance company. If the lightning strike had damaged the insulation to the point that it would arc destructively the next time it reached 1.5x normal voltage, such a condition might not get noticed for years even with arc-fault interrupters installed. If the property had been sold before that occurred, it may be essentially impossible to hold responsible the company that insured the property at at the time of the original lightning strike.

Note that insurance companies view risk somewhat differently from individuals. From their perspective, it's better to spend enough money to definitively resolve a claim than to spend a lesser amount to "probably" resolve it. While I've never had to file such claims, I would expect that many insurance companies would rather pay the cost of such testing and know immediately whether they would or would not also have to absorb the costs of repairs, than install AFCI devices and hope for the best but never really "know".


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