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The surge from a nearby lightning strike has resulted in multiple fried electronic devices at our house. Damaged items include a cable modem, 2 cable set top boxes, a cable amplifier, a WiFi router, 2 garage door opener circuit boards, a hot tub control panel circuit board, an irrigation power cord transformer, Ethernet ports on 3 desktop computers and a power strip in the kitchen.

The main electrical panel has a Siemens QSA2020 Type QP circuit breaker & secondary surge arrester with a current interrupting rating of 10,000 amps. This breaker did not trip. The irrigation power cord transformer was plugged into a 400 volt surge protector with was fried as well as the transformer.

Questions:

  1. Why did the Siemens device not trip?
  2. What should be done now to help prevent a similar future outcome?
FreeMan
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Lee E
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    What is the manufacturer and model of the surge protector in the panel? Where is this property located? Did other properties nearby have similar damage? – Jim Stewart Aug 14 '19 at 09:13
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    Even without a direct strike, nearby lightning can induce currents in wiring that can damage devices in spite of panel-based protection. – jwh20 Aug 14 '19 at 11:01
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    Might have struck the incoming cable instead. – gnicko Aug 14 '19 at 12:10

2 Answers2

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I have repaired 2 homes that had lightning strikes 1 was direct and there were breakers all over the house (it burned the bus was even partly melted) the second one was an indirect strike. The damage to the electronic components is due to the high voltage more than the current. With that said surge suppressors clamp the voltage until they overheat and fail.

A whole house surge suppressor in your main panel may have helped if it was large enough, the second house that was a indirect strike was protected by a suppressor that could handle close to 30 amps. The suppressor was toast both elements failed but they only lost 1 TV set that was on when the strike hit.

How surge suppressors work:

Most are metal oxide varistors. These devices conduct once a voltage threshold is reached and dump the excess voltage to ground the voltage threshold on some that I have used range from ~260v and higher close to 800v.

in the U.S. the maximum voltage voltage to ground is 120v rms for residential. 240v is leg to leg but the maximum potential to ground is 120v rms so you want a MOV that breaks down in the +200v range.

Next is the amount of energy that the mov can conduct rated in joules. Once this value is exceeded they do fail. Whole house units usually have led’s that show if the elements are working, some are replaceable.

As you found out the one on your pump failed it tried to do its job but was not large enough. I suggest putting the largest one you can afford at your main panel.

I usually install these because of industrial loads causing spikes and damaging electronic equipment. Oregon is not known for its thunder storms and having seen 2 strikes is very rare here.

I can say nothing will stop a direct strike but an indirect strike or industrial loads and power line switching all generates spikes that can do damage by installing a 300$ or larger surge suppressor may save many times its cost over its life there are smaller ones for under 100$ these are very limited on the size of the spikes they can handle and some that cost close to 1000$ these monsters can almost take a direct strike.

I have found the ones that require a 30 amp breaker to be the best value for my area and they do not fail very often where the smaller ones do fail more often so in my opinion going with a larger unit will provide better protection and possibly last forever unless a close strike.

So why did the breaker not trip?

It could have been the current / duration was low enough not to trip but the voltage did the damage. This is where whole house surge protection pays off just make sure to get one that is large enough to handle the spikes that may happen in your area.

newcoder
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Ed Beal
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    Ed, I’d strongly suggest you edit your answer to split it into paragraphs. You should know how hard it is to read a wall of text. – DoxyLover Aug 14 '19 at 20:49
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A whole building surge protector that really works does not exist

http://www.us-tech.com/RelId/1082596/ISvars/default/Why_Whole_Building_Surge_Protectors_Don%27t_Work.htm

EPRI, in a "System Compatibility Research Project" concluded ". . . with the `lower bidder' (lower clamping level) downstream SPD (point-of-use protector) absorbing most of the energy. This means the upstream SPD (whole building surge protector) remains passive: not only a waste of resources, but also a possible problem of inviting the large surge currents to flow deep into the power distribution system, where they can cause interactions with adjacent circuits, defeating one of the benefits of whole-house surge protection.

ron
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    best thing to do if you've already wasted money on a whole house protector is save the purchase receipt and try to claim their $10,000 warranty or whatever was advertised, and good luck in trying to do so. – ron Sep 13 '19 at 17:28
  • I strongly disagree I have installed these in an area close to Mary’s lumber mill, prior to installing these devices the owners regularly lost electronic equipment totaling thousands from the spikes the large motors put on the power lines within a year of the first install I had 3 more neighbors that had similar problems, before leaving that area I had installed a dozen with 1 cheaper unit that had to be replaced, as I said in my answer nothing will stop a direct strike but line surges from non direct strikes and industrial and power company switching the spikes can be dampened. – Ed Beal Jun 10 '20 at 21:29