Panel Explosion

[Mystic Pools]

Jandy 100 amp sub-panel at my customer's. It's about 8 years old.
Blew up. No lightning strikes I'm told by my customer. The door blew off 15+ feet and hit the property fence.

Happened about 2 weeks ago on a rainy day. Neighbors heard the explosion. My customers was home at the time.
He told me the week before he noticed an electrical burning smell and remove the cover plate. Saw nothing out of the ordinary (not an electrician but is a contractor and would notice something out place)

Everything destroyed. There's actually a high voltage and low voltage surge in that crispy critter. Jandy computer board, all the breakers, salt water generating guts-all done.

 

[synchro]

It would be interesting if you could tell whether a surge protector was the point of origin for the explosion. I've always been somewhat wary of SPDs since their purpose is to clamp overvoltages and dissipate excess energy in a localized spot. I also wonder if it's possible to have degradation or failure modes where a SPD starts to clamp at lower voltages, heats up, and even explodes.

 

[Mystic Pools]

I think that's the case. I have not been to the site to see up close, but the high voltage Intermatic SPD is on the bottom right. From the charred area, it looks like it started there.

 

[Jraef]

MOVs protect by sacrificing themselves, but with enough energy in the spike, will do so "with extreme prejudice". The Metal Oxide in them will vaporize, creating a conductive cloud that then causes a flash-over in the space. I've never liked putting MOVs in the same enclosure as expensive gear for that reason. I had some blow at a large pump station and take out 3 600HP 4160V Soft Starters. The manufacturer had put them on the inside of the Soft Starters, but also connected to the line side of the isolation contactor, so they were connected to the grid all of the time. One lightning strike 10 miles away and they all exploded. The protective relaying on the substation tripped the source breaker, but then the operator panicked about the station being down and reclosed it, which then caused the flash-over inside of the soft starters and blew everything up. That was about a $250k event.

 

[hbiss]

MOVs protect by sacrificing themselves, but with enough energy in the spike, will do so "with extreme prejudice". The Metal Oxide in them will vaporize, creating a conductive cloud that then causes a flash-over in the space.

So now we are required to provide surge suppression for every new service. Get ready for a lot more of what you see above.

-Hal

 

[augie47]

So now we are required to provide surge suppression for every new service. Get ready for a lot more of what you see above.

-Hal

Which Code cycle requires that.
I knew '17 required surge on some installs like Art 670 & 695. When is it an "all service requirement" ?

 

[ActionDave]

Which Code cycle requires that.
I knew '17 required surge on some installs like Art 670 & 695. When is it an "all service requirement" ?

2020 code and I believe they added a section just for surge protection.