Power Spike questions

About a month back, after a series of snow storms etc., my wife and I were picking up dinner around 8:00 PM when we heard a loud explosion and a bright flash of light outside of the house that was extremely bright. Instantly we lost power.
We ran around the house to try and figure out what happened. The Carbon Monoxide detector at one outlet had actually ruptured and the outlet was a scorched black. We also found several devices such as phone chargers, emergency lights, surge protector power strips that were plugged into outlets that also got fried.
After getting it reported to the power company, a technician showed up the next day and found the service meter had also toasted. It was charcoal black inside the glass.
The explanation for the event was a problem on the mainline that sent 69,000 volts to the house for a fraction of a second before the fuses on the feeder line blew.
After changing the meter and they repaired the line, the technician came back and had me try the power. Lots of outlets didn't work, refrigerator, freezer, lights. The computer survived along with a printer and satellite tv box and a satellite internet box.
The technician said to notify their claims department, which I did.
A few days later I was able to get an electrician out to look at it.
The service panel was beyond repair. The main buss bar in places was actually vaporized, gone. Looked like a plasma torch went through it.
After that and still waiting for electrician to schedule all of the powers to be to get permits, shut offs, inspectors etc. It was get by with what worked. Extension cords ran around the house.
After that spike, 2 weeks, in the middle of the day it happened again. I was having a sandwich and out of the corner of my eye there was a flash and a crack like a gunshot. Not as dramatic as the bomb first spike.
First check was the service panel. Meter got it again. The same technician came back and changed the meter out about midnight. He said a crew would be back next day to fix the mainline.
The crew showed up and I was told a tree took out the mainline. He explained that they were installing lightning arresters on the pole 50 yards from the house where the step down transformer is. From there the power is underground to the house. The arresters were installed to prevent another high voltage spike to the house.
After this event computer, printer, tv and internet boxes, most all of the light bulbs I had just replaced and a UV water purification system were all burnt up.
This is timber county and we get heavy snow.
My question is how in the world does mainline voltage cross over to a feeder line and through a step down transformer? My electrician said that this should never happen. And to happen twice ?
Our neighbor, the one and only for miles had similar events and damages as well.
I guess my big question is what the power company guys aren't telling me?
Sorry for the long story, but it's pretty much the short version with all the grief left out.
Thanks.

Simple...magic...

The pole pot is what converts to high voltage to line voltage and the ground on output at pole and down to your meter is the reference.

If the ground blows open then the pole pot can be floating and if any part of secondary touches primary then high voltage at the house.

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I get it. That's kind of how they explained it but not as detailed as you describe.
So what they call lightning arresters that they installed, are an additional security of maintaining a ground?

A neighbor down the street had that happen with a 4160V line. Blew the breaker box, with the mains hanging out the front, scorched a bunch of outlets, blew out all the electronics that were plugged-in. A tree fell on the line, and the 4160V wire fell right onto his 240V drop line. He had me look at it, wbich I did once I saw that his drop lines were all down and clear of the high voltage. I was surprised he had no fire.

The lightning arrestors are an alternate path to ground for any high voltage. The problem with them is that they may take quite a bit of voltage to start working, and that may still be too much for your stuff, even though it is lower than the distribution voltage.

Arrestors vary in the type they are. Some are a spark gap, which arcs over at a sufficiently high voltage, at which point the arc holds the voltage pretty low. Another type are a solid material, used to be (and may still be) "Thyrite". This stuff is in one or more blocks, which may be stacked up. Each block is rated for a certain voltage, so they can be stacked for higher voltage. It is normally almost an open circuit. as voltage increases, the resistance rapidly goes down, bypassing the current.

With a sufficient overvoltage and current capability, the thyrite (or whatever) may be just melted and it then holds pretty low resistance. I have seen that happen once at work where lightning melted it and power was out due to the fuse blowing because of the resulting short on the line. They showed us the block, it was about 2 or 3 inch diameter and had a round melted spot of about an inch diameter. If sufficient current flows, it may cause an explosion if there is any water trapped in it or its holder.

More likely the explosion was the fuse opening. They can be pretty violent, and are designed to expel any molten material and quench the arc. Can make a spectacular show, and a loud noise. This one in daytime shows no particular flash

Loud explosion blown fuse transformer bank Chamberlain SD - YouTube

Very interesting information.
It sounds like no guarantee it won't happen again, so I'm looking at replacing all of the surge protector power strips that were most likely not sufficient.
Found some that are rated for 3,000 Jeules and have some kind of protection warranty of 30,000 dollars.
My neighbor spends a lot of time away for her job, so she is shutting off her main at the service panel when she leaves. Definitely that will help increase the odds of electronic survival for her.
Not really an option for us since we are home mostly every day.
I have my claims started for the power company and they give 6 years to submit.

Surge protector power strips would not protect you in cases like what you described and on top of that, 90% of them are totally useless anyway. The better route is what's called an SPD (Surge Protective Device) from a good reputable company (like GE, Eaton, Square D or Leviton) installed at the main disconnect of your house. The only ones worth using are not cheap, so it's going to come down to a cost-benefit equation. If you do it though, spend the few extra dollars to get one that gives you an indicator to let you know it's no longer there. They basically only work once in a big hit like what you saw, they sacrifice themselves in the line of duty. But if they truly do their job, you never know they did so you don't know they are not there for the next one.

Jraef said:

Surge protector power strips would not protect you in cases like what you described and on top of that, 90% of them are totally useless anyway. The better route is what's called an SPD (Surge Protective Device) from a good reputable company (like GE, Eaton, Square D or Leviton) installed at the main disconnect of your house. The only ones worth using are not cheap, so it's going to come down to a cost-benefit equation. If you do it though, spend the few extra dollars to get one that gives you an indicator to let you know it's no longer there. They basically only work once in a big hit like what you saw, they sacrifice themselves in the line of duty. But if they truly do their job, you never know they did so you don't know they are not there for the next one.

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Never knew that. Very interesting!

Any decent line protectors are going to be BIG, doorknob size for MOV types, maybe different for spark gap types, and combination types are different again.

I have a leviton device on the breaker box, it is as big as a good sized junction box. Has lights to verify it is operational. I don't know that this type are still sold, but so far so good.

JST said:

Any decent line protectors are going to be BIG, doorknob size for MOV types, maybe different for spark gap types, and combination types are different again.

I have a leviton device on the breaker box, it is as big as a good sized junction box. Has lights to verify it is operational. I don't know that this type are still sold, but so far so good.

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Probably are.

I worked for a long time for a company based in the Tampa area, which is the "lightning capital of the world". I live in the SF bay area, we hardly ever see lightning, I paid little attention to it. But holy-moly it was "shocking" to see a Tampa Bay lightning storm in full glory the first time! My coworkers taught me a LOT about surge protection, especially about what was a complete waste of money. Many of them had worked for a small start-up SPD mfr in that area and that company is what I think Leviton bought to get into the business.

Good information here. I appreciate it.
The same technician came back today for a different reason since there are flooding issues in the area. He pointed out the arrestor to me in our discussion. It is a grey knob looking device mounted to the side of the transformer. He explained it is designed to take the hit but basically may not act quick enough to prevent a high voltage surge from crossing over to the 220 side.
He said that the claims process is about our best option.
Falling trees and heavy snow are their nightmares.

Here are a few typical for the customer side line not the high voltage side)

https://www.surplussales.com/Semiconductors/SemiCTransSup.html

Ge 9l15ecc1 Tranquell 3-pole Secondary Surge Arrester 65vac | What's it worth

Here is an example of the stack-up type for use on power lines in a housing

TGE Metal oxide arrester, Lightning arrester,Surge arrester

And here are some that may or may not have replaceable elements, I didn't look closely. The replaceable ones are usually a bit fatter.

http://www.cablejoints.co.uk/sub-product-details/cable-socks/hv-high-voltage-surge-arresters-polimd

Conant,

Are you at the end of the line (dead end pole) by chance?

Murf said:

Conant,

Are you at the end of the line (dead end pole) by chance?

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Yes. Pretty much. In this area we only have one neighbor for miles.
Neighbors power drops down from grid to a feeder line to her house. She's on the end of that line, last pole as you say.
Ours is slightly different. From the grid a line drops down the hill and on to the freeway for offramp lights. Our home Ts off of that line to it's transformer. Last pole on that line.
The neighbor seems to have more spike problems then we do.
As the technician put it, we are at the end of the line.

Murfreesboro, what's the theory behind the last /dead end pole?

conant said:

Murfreesboro, what's the theory behind the last /dead end pole?

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If a cross phase or a lightning strike occurs on the line it always travels to the end of the line or until it finds earth ground. A dead end pole almost always has a step down transformer on it to serve a customer, otherwise it would not exist as the utilities do not run pole lines to nothing (except the rare instances where the service has gone idle or been removed). With that said if you start looking at poles like yours (dead end) you will usually see a transformer, fusing/cutouts for that transformer and surge protectors (also called lightning arrestors) and two seperate earth ground runs, one for the transformer itself and one for the surge/lightning arrestors.

Plus, the dead end is "open", causing an "impedance mismatch" so you generally get an especially high voltage on it when the traveling voltage disturbance gets there. You can imagine it as the electrical equivalent of "water hammer" without being too wrong.

conant said:

Murfreesboro, what's the theory behind the last /dead end pole?

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Looks like the good old smart phone really twisted Murf into something interesting.
Sorry, I need to pay more attention.

This may seem like a personal complaint and a bit of wining, but the claims against the power company for all this stuff and the value of it, hardly makes up for the inconvenience, grief, and all of the personal time that has consumed my life, and my wife's.
Trips to the dump with bags of spoiled food, stench of disabled freezer and refrigerator, storing whatever food we could save at families homes etc.
Probably not compensation for that without attorneys, which I always seem to lose more than gain with those guys.
I guess next year, when the smoke clears, kind of literally, it may even raise a little chuckle looking back at it.
Definitely not right now though.
Seems like living here has given me a whole new bunch of acquaintances. How often is anyone on first name basis with power company technicians. Great people actually. I have a lot of respect for them.

Another option beyond litigation for additional losses, would be to get a quote for one of the surge protection devices mentioned, then bring it up alongside your claim and try to get the power company to pay for it. they may prefer that option to a lawsuit, if you explain your situation correctly.

apoc_101 said:

Another option beyond litigation for additional losses, would be to get a quote for one of the surge protection devices mentioned, then bring it up alongside your claim and try to get the power company to pay for it. they may prefer that option to a lawsuit, if you explain your situation correctly.

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I am a little confused to which post above and which surge protector to research. I went online to research some and got totally lost in the usual sea of information.
I will definitely give that a try.
What really came up in my mind after all of this, is why it took the two spikes within a two week period for the power company to finally put the arrester on that I feel should have been there all along.