Primary falls on Secondaries...

[hurk27]

To address the high-energy transients, a spark gap is usually used. The whole-house devices I have seen don't look like they can handle that much energy. Not sure what the joule rating is but it is most likely intended to handle very brief surges causes by lightning, etc.

Even a Spark Gap would not have prevented this damage, as where would the current gone?, with only ground rods, even a solidly connected neutral conductor to the GE's did not stop it, this is why I feel driven electrodes are worthless.

 

[mivey]

Even a Spark Gap would not have prevented this damage, as where would the current gone?, with only ground rods, even a solidly connected neutral conductor to the GE's did not stop it, this is why I feel driven electrodes are worthless.

Not sure what would have completely prevented it other than being isolated.

It would not have had to travel on the ground only. Even in the OP's case, I'm sure most of this activity was on the grounded and ungrounded conductors.

 

[hurk27]

Not sure what would have completely prevented it other than being isolated.

It would not have had to travel on the ground only. Even in the OP's case, I'm sure most of this activity was on the grounded and ungrounded conductors.

There would not much that would have prevented the OP damage except maybe a city water supply system, properly bonded. surge suppressors would have had very little to no effect in stopping this kind of voltage or current. I have seen both what happened in the OP and as mention a higher voltage line hitting a lower voltage line, in both cases surge suppressors failed, and in the latter some caught fire,

you must have missed this post see in red, a low impedance path back to the transformet, I.E. water pipe to service next door

If on the same transformer

 

[mivey]

you must have missed this post see in red, a low impedance path back to the transformet, I.E. water pipe to service next door

If on the same transformer

I don't see how a bonded city water supply would have prevented damage. Even if the city water main went through the meter base and the neutral was cad-welded to it you could still have had damage.

Maybe it is just late but perhaps you could elaborate.

 

[hurk27]

I don't see how a bonded city water supply would have prevented damage. Even if the city water main went through the meter base and the neutral was cad-welded to it you could still have had damage.

Maybe it is just late but perhaps you could elaborate.

Maybe but the low impedance path would have at least brought the voltage way down, applying a 1 or 2 ohm load across the primaries would effectively brought it down to a lot safer level. short out a long extension cord, even if the breaker doesn't trip, the voltage goes to almost zero at the shorted end. and a copper water pipe would make for a great short.

Of course if the connections are good, as I stated "a properly bonded water main"

I also dont think it went through the ungrounded conductors from the pole as the fuses at the main disconnect wasn't blown.

 

[macmikeman]

If you like, I will fly you to NY. We are having a number of days with storms similar to the one that caused this damage. We are supposed to have a large number of storms on Friday.

Are you packed yet?

Heck yes I am. :grin: Thats a Mighty Generous (sp?) offer, thanks.....
Always wanted to see the big apple,never got closer than Pittsburger. See you Friday morning, by the way I upgraded that ticket you sent to first class.:grin:

 

[quogueelectric]

The reality of the matter is at MV levels 4160 or as high as 13200 these levels dont care if there is an additional or subtractive 120 volt wave on line or in the way of a flash over to ground. at 120 volts it sees it as ground. It may as well be ground. There is no way to see the possible damage in closed walls and I am not rolling the dice with my assets for a 20,000$$$ remodel. It is NOT happening on my watch. Hey it sucks to be you but I am not putting my neck on the line because a megger shows me good values on a charcoal encrusted MNB in a closed wall. You had better keep good records if you are crazy enough to put yourself in harms way for a job like this. Total rewire old work call the insurance co. What happend in the panel could have easily happened in the walls.

 

[Sierrasparky]

How about if they installed AFCI breakers ....

 

[quogueelectric]

How about if they installed AFCI breakers ....

more toast for the event.

 

[Pierre C Belarge]

The reality of the matter is at MV levels 4160 or as high as 13200 these levels dont care if there is an additional or subtractive 120 volt wave on line or in the way of a flash over to ground. at 120 volts it sees it as ground. It may as well be ground. There is no way to see the possible damage in closed walls and I am not rolling the dice with my assets for a 20,000$$$ remodel. It is NOT happening on my watch. Hey it sucks to be you but I am not putting my neck on the line because a megger shows me good values on a charcoal encrusted MNB in a closed wall. You had better keep good records if you are crazy enough to put yourself in harms way for a job like this. Total rewire old work call the insurance co. What happend in the panel could have easily happened in the walls.

I am not too sure how much work like this you have seen, but lately insurance companies are not paying if the readings are not bad.
It would seem that some would not perform this repair job...maybe you have all your bills paid and the kids are not hungry.
This contractor has hungry children.

 

[hillbilly]

If it were my home...
I might just repair the damage.
Then again, I might rip it all out and replace it.

How would I decide.
I would inspect the damage that I could see, that includes looking in every junction box in the home.
I would Megger the wiring.
Then I would use my experience and judgement as to whether the repair would create a safe installation.

Safe to me equals..... "Would I allow myself and my family to sleep in the house after the repair"?

I apply that rule to every job that I do, no exception

Just my opinion
steve

 

[Jim W in Tampa]

If it were my home...
I might just repair the damage.
Then again, I might rip it all out and replace it.

How would I decide.
I would inspect the damage that I could see, that includes looking in every junction box in the home.
I would Megger the wiring.
Then I would use my experience and judgement as to whether the repair would create a safe installation.

Safe to me equals..... "Would I allow myself and my family to sleep in the house after the repair"?

I apply that rule to every job that I do, no exception

Just my opinion
steve

Short of removal of drywall just how could you be sure what was damaged ?

 

[mivey]

Short of removal of drywall just how could you be sure what was damaged ?

You couldn't be positive and you might have a modern day version of K&T. A severe fault could create enough force to pull the wires together in the future but what else are you going to do?

You could remove some boxes to gain access to some of the area behind a wall if you were suspicious. But eventually you will weigh economics vs. safety, like we do all the time.

 

[TwinCitySparky]

I find these types of incidents interesting. When I upgraded my own resi service I put a fused disco outside, even though I have a main breaker panel, just for kicks. I've often wondered if putting a 3 phase disco and fusing the incoming neutral would provide more protection from accidents like this ?

Might provide more protection from this event but not code compliant as I know you know.

Wouldn't it be nice to come accross a house like this and find out it was originally piped. :grin:

 

[Sierrasparky]

In the old knob and tube and glass fuse days the grounded conductor was fused. There are plenty of houses out there like this.
I wonder what the thinking then was?

 

[slick 50]

In the old knob and tube and glass fuse days the grounded conductor was fused. There are plenty of houses out there like this.
I wonder what the thinking then was?

Maybe the reason why they do not want to fuse the neutral is in case the fuse blows and you get inbalanced voltages through out the system that could cause lots of problems. A good idea would be to have the main breaker a switched neutral breaker. This way any issues regardless of where the problem would be, both hots and the neutral will simutaneously disconnect, hopefully protecting every circiut of the system.

 

[hurk27]

I am not too sure how much work like this you have seen, but lately insurance companies are not paying if the readings are not bad.
It would seem that some would not perform this repair job...maybe you have all your bills paid and the kids are not hungry.
This contractor has hungry children.

The problem with a case like this is, if the insulation was blown off the conductors, and these can show good when megged, you now have bare ungrounded conductors laying against wood framing members, and over time it can cause PRO-carbonization errr something to that effect, but using a camera snake down wall where NM might cross other metallic paths such as gas lines, cable, phone, etc. at least will show a better picture of what your dealing with.

 

[mivey]

...but using a camera snake...

Hadn't thought of that. What's an inexpensive one cost?

How do you get it to follow the cable? I have a hard enough time getting fish sticks to behave in insulated walls.

 

[Jim W in Tampa]

Insurance company might refuse but i would take it to court . #1 this house is now devalued for life same as a car is after a wreck and yes they must pay. How do we turn this into a poll ? Would any electrician trust this house without rewire to live in with wife and kids ? Meger is just one test. If that fails yes replace but that alone does not mean its fine. If mine i would open up several areas an inspect till i find just 1 spot they missed. Then charge for my time plus rewire. Who is paying bill ? poco ?

 

[quogueelectric]

I am not too sure how much work like this you have seen, but lately insurance companies are not paying if the readings are not bad.
It would seem that some would not perform this repair job...maybe you have all your bills paid and the kids are not hungry.
This contractor has hungry children.

I will not install or repair any situation which I dont feel is totally safe when I walk away. I would not sleep in a house nor let my kids and wife nor would i let you sleep in a house that has been hit by a substantial overvoltage. The megger only reads insulation values and air is an insulator when it is not ionized. All a megger can tell you is that the circuit wont blow up when energized. 2 feet away from the test the conductors could be a charred molten mess hidden in the wall with the ccc blown apart down to a 22 guage conductor just waiting for a load to light a fire in the wall. The entire insulation could be melted and dripping off yet it could still read fine. The megger has a very limited use on what it can tell you. yes I would let myself and my kids go hungry for a day rather than killing a customers family in a fire that I couldnt properly test to be certain that they were ok.