Scary night- shop almost burned- question: Can a power surge cause a fire?

[Malcolm Schweizer]

I was sleeping soundly in my hotel room when I got a text message that woke me up. It was from my wife: "Hey, there's a fire downtown, and it looks like the building your shop is in." The building is visible from our house, so she sent this picture:

Fire.jpg

So, that building is directly adjacent to my shop, only separated by an 8' wide alley. My back door opens to their back door. Very scary, as I was travelling, and I wasn't able to go check on my shop. NEXT- I get another text- "Hey, now there's another fire behind Waterfront." About a block away- another fire. Of course my first thought is arson.

The next day, my wife talked to the owner of one building and he said he believes it was caused by a power surge that started an electrical fire. The upstairs space where the fire started was just being finished with a renovation. In the other building, the fire started in a storage area with a walk-in cooler for a restaurant. I would say that it's not likely to be arson because they started in the least accessible places of the buildings.

I don't see how a power surge could start a fire unless something wasn't wired correctly, which is very likely where I live. Lots of- how can I say this- "creative wiring solutions" here. So, yes- certainly if something isn't wired correctly it could start a fire, but my question is, can a power surge start a fire if something is properly wired and protected with breakers? I have a main breaker between my meter and my house, and then of course breakers for each circuit. It seems a power surge would trip a breaker before it caused a fire. We do get a lot of power surges here, to the point that when you buy an appliance, they make you plug it in and sign showing that it did work when you left the store, because people were bringing back appliances after being power surged. I put a whole house surge protector, and have additional surge protectors at the plug for expensive electronics.

Thoughts? By the way- my shop is fine- our firemen put out the fire before it spread. Unfortunately, a number of other businesses were damaged by the second fire.

[Mike Wilkins]

After working in the insurance claims industry for years, I have seen power surges start fires and even burn a house to the ground. A fallen tree on a power line and lightning can cause a surge of electrical power through an electrical system. The utility company can install a surge protector in line before the meter, but even that is no guarantee.
Make sure your insurance policy is up to date.

[Rod Sheridan]

Hi Malcolm, glad to hear that your shop is OK.

Yes a power surge can start a fire, either through electrical insulation failure due to voltage stress or the complete failure of solid or air insulating systems due to over voltage or transients.

Large over voltage incidents can cause catastrophic failure of equipment, I've seen equipment blown through walls or off the side of buildings. That's why I would never mount an arrestor in a building......Rod.

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[Perry Hilbert Jr]

I lost a shop and house to a fire 4 years ago this very day. Everything but the clothes on our backs and whatever was stored in the cars and barn. Lost our two old dogs and two young pups too. Firemarshall said electrical, but nothing more than that. I was an old house and when I bought it 20 years earlier, I had all the old knob and tube ripped out and replaced. Had the service increased from 60 amp and made several improvements. We had a terrible problem with stray voltage in the pump house and barn. (a separate electrical system and meter) . It got so bad I was buying wire that had the ground wire covered in green plastic. The electrical there is grounded in three separate locations and I have had two licensed electricians out to go through everything. They tell me the source of the stray voltage could be from the ground, from static or even from magnetic waves. I have two surge protectors on that system. one for the system as a whole and another for the well pump. We have a huge number of lightning strikes close by every year. I have no clue what else I can do, except move.

[Malcolm Schweizer]

Thanks for the replies. Perry, I am very sorry for your loss. I was thinking a surge would blow a breaker, but I now see why it could still arc or cause enough heat to still cause a fire. My shop is new to me and I have not even wired it yet. Currently it is a storage for wood and boat parts, but I am hiring someone to properly wire it. This weekend's fire was eye opening. I would have lost thousands of $$$ in lumber and a new outboard still in the box that I literally got the day before I left for my trip.

For sure I am having a panel surge protector installed, and the main breaker will be thrown whenever I leave.

[Mike Cutler]

Yeah, surges can definitely cause fires. Add in some dust, spider webs and dust, old wiring , maybe a few things that could have been done better, and they can start.
You'd be surprised at what might not cause a breaker, or surge protector to trip.
Electricity is going to find ground.

[Bert McMahan]

Regarding the surges and breakers- the breakers are there to protect your wires, not your devices. An average desk lamp cord may be able to handle only a few amps despite being plugged into a 20A breaker. If you had a big enough voltage spike, you could start driving 5 amps through your 3 amp cable, even though the breaker isn't tripping. This would then cause the lamp cable to overheat, potentially causing a fire. Typically this would only matter for *sustained* overvoltage conditions, but if (like others have said) you have a tree fall on a power line, you could suddenly have two circuits get crossed that weren't meant to be crossed. For example, you could get mains voltage on a phone line or something, which would then rapidly overheat the wiring, causing potential ignition.

[Malcolm Schweizer]

Interesting. I’m most concerned about my house, which is on a different feeder than the shop, but if a spike happened on that feeder, it could certainly happen on the one I’m on. Losing the shop would be a fianancial blow, but losing the house would be an emotional one.

[Dan Hall]

Do you get a lot of lightning strikes where you are? If this is a frequent event I think the utility should be involved. If lightning is making direct strikes on power lines you got a problem. There is not a lot to be done in my opinion other than keeping your insurance up to date.
On the other hand I was called out on a consult last year for a well feeder problem on a house that was for sale. A prospective buyer had hired a pretty savvy inspector who found what he called a leak in the well feeder. I took my megger with me and disconnected the direct burial well feeder at both ends. Sure enough one hot leg had developed a high resistance short to ground. Probably thorough water incursion into the jacket of the cable. The megger saw it as a short but my multimeter told us that it was in the range of about 200 ohms. It was not enough to trip the breaker but certainly enough to keep the worms moving. This sort of thing can cause circulating currents to appear just about anywhere. I persuaded them to dig a new trench and put in a new well feeder.

Remember, the neutral and the ground of any premises wiring system must be solidly grounded at any convenient point between the service entrance conductors and the first disconnecting means and nowhere else.

I'm going to research the two services issue. I think that the grounding electrode conductors of the two systems should be bonded together. In the olden days we had all metallic water piping systems that provided that bond. That is no longer the case.

[Dan Hall]

I wouldn't think Perry that you got a satisfactory answer there. No single premises can have two services but in your case you see it all the time. The well house isn't a premises. I need to think and research this one.

[Jim Andrew]

There was a fire at a cabinet company I was buying from once, the owner showed me some breakers that had copper shoved through them, to the point the power could not be turned off. Lightning.

[William Batdorf]

Please be sure to thank the firefighters. They didn't start the fire but you can bet they did their very best to put it out! I'm glad your shop is OK.

Bill B. Fire Officer/ EMT 35 yrs. service

[Nicholas Lawrence]

Saw a house once where the power company made a mistake reconnecting after a blown transformer. Pure line voltage straight into the house. Fire department got there pretty quick, but you could see every wire in the house outlined on the wall where they overheated and set the adjacent wall on fire.

[Malcolm Schweizer]

Do you get a lot of lightning strikes where you are? If this is a frequent event I think the utility should be involved. If lightning is making direct strikes on power lines you got a problem. There is not a lot to be done in my opinion other than keeping your insurance up to date.
On the other hand I was called out on a consult last year for a well feeder problem on a house that was for sale. A prospective buyer had hired a pretty savvy inspector who found what he called a leak in the well feeder. I took my megger with me and disconnected the direct burial well feeder at both ends. Sure enough one hot leg had developed a high resistance short to ground. Probably thorough water incursion into the jacket of the cable. The megger saw it as a short but my multimeter told us that it was in the range of about 200 ohms. It was not enough to trip the breaker but certainly enough to keep the worms moving. This sort of thing can cause circulating currents to appear just about anywhere. I persuaded them to dig a new trench and put in a new well feeder.

Remember, the neutral and the ground of any premises wiring system must be solidly grounded at any convenient point between the service entrance conductors and the first disconnecting means and nowhere else.

I'm going to research the two services issue. I think that the grounding electrode conductors of the two systems should be bonded together. In the olden days we had all metallic water piping systems that provided that bond. That is no longer the case.

I thought I had responded to this, but I guess it didn't post. This wasn't lightning. Lightning here is very rare because storms build up and dump too quickly. If we get lightning, it means a tropical storm or something huge.

Please be sure to thank the firefighters. They didn't start the fire but you can bet they did their very best to put it out! I'm glad your shop is OK.

Bill B. Fire Officer/ EMT 35 yrs. service

Absolutely, and thank you for your 35 years of service. I'm doing something for them next week. Maybe you can tell me if this is too cheesy (pun not intended) but I was going to buy pizzas for that company to say thanks.



Here is a link to a very interesting article about the fire- it turns out a few other businesses had their refrigeration fail the same night.

https://stthomassource.com/content/2...HPFSRwkiNN8pUE

By the way, if that image at the top looks familiar, yes, they took it from my wife's Facebook post.

This was clearly a power surge of some sort, and it's typical of our Water and Power Authority (WAPA) to have surges and dips. Our power system is very aged and power failures are very common. Power dips and surges are so common that when you buy a TV at Price Smart, they make you plug it in and sign that it was working when you left the store, because so many TV's were coming back damaged from surges. I have a whole house surge protector on my house, and on all appliances and electronics I have individual APU's with surge suppressors. The refrigerator has a device that if the power goes out, it keeps the fridge off for 5 minutes to prevent any on/off surges when the power blinks as it comes on.