Electricians - ever seen this before?

[fedtime]

We had lightening strike close to our house. Following the strike, I went down into the basement and found this - a hole in the ICF foundation wall, melted styrofoam and pieces of concrete and drywall scattered throughout the room. NS Power comes out and says the lightening strike travelled in the neutral and exited to the ground at this point.

Thankfully, I had followed the advice of members here and had unplugged the pellet stove and surge protector.

 

[begreen]

Yikes. That was close. You were lucky. I've seen a lot worse. Hopefully that is the full extent of the damage. Good for you protecting the stove.

 

[kenstogie]

wow.

 

[tfdchief]

There is no guarantee when it comes to lightning, but proper grounding and bonding of all systems (per the NEC) is extremely important and goes a long way. Many systems out there are not properly grounded and bonded. This includes electrical, telephone, cable, satellite, water, gas.

 

[fossil]

EEK!

 

[Bioburner]

Lightening, if you cant afford to replace it, unplug it. That high of voltages writes its own rules. I've installed four independent grounds in our house.

 

[tfdchief]

Lightening, if you cant afford to replace it, unplug it. That high of voltages writes its own rules. I've installed four independent grounds in our house.

Bio, I am not sure what you mean by independent grounds, but if they truly are, that can be a problem. In order to have the same ground potential they all need to be bonded together, and that is required by the NEC.

 

[Bioburner]

As you had posted earlier, well line(I lost a building due to lightening entering from well)tv aerial, telephone, ground for power amp for entertainment center and the main power feed. A lot of rod and copper cable.

 

[fedtime]

In my case, I'm told the strike travelled in through the neutral - not much you can do about that I don't think. Anything that was on that basement circuit, plugged in and operating was cooked. I lost a fairly new dehumidifier - a small loss compared to what could have happened. The lift pump for the basement bathroom/laundry was plugged in but not operating and it seems ok.

During my last year at sea, all of the ships owned by the company I worked for were being converted to break the hot(s) and the neutral because of the concern that power (eg. short to the neutral) or a lightening strike could feed back through the neutral.

 

[hockeypuck]

The fact that it decided to exit in your basement could mean your service ground is inadequate. Most service grounds in the north east are poor at best. New construction requires you to tie into the rebar in the foundation footings, which is the best you can do in this area. Code states you have to have two grounding electrodes.. various items qualify or meet 25 ohms(?)to earth or better on one electrode. Most pick two electrodes and be done with it.. It is to code.. but usually not enough. Lighting does follow its own rules. You can only give it an easy path to ground, but that usually does not help.

 

[hockeypuck]

Bio, I am not sure what you mean by independent grounds, but if they truly are, that can be a problem. In order to have the same ground potential they all need to be bonded together, and that is required by the NEC.

True. Best bet is to tie them together at the service entrance point. If there is no disconnect between the meter base and the main panel, you can tie them together at the main panel as well.

 

[smwilliamson]

Had a customer that had a lightening strike on the chimney and it followed a wire in the wall to their closet and literally cooked all of the clothes on the metal hangers then blasted a hole in the siding 10 feet around before grounding out on the patio table umbrella. They were aeep the whole time and woke up to the smell of hair burning... Which was her fur coats on the closet.

 

[Lake Girl]

Glad no human or pet injuries and no fire Pain in the butt to replace things but pretty minimal in the scheme of things. Forces of nature can be pretty awesome to behold...

 

[westom]

In my case, I'm told the strike travelled in through the neutral - not much you can do about that I don't think.

If true, then major human safety threats remain. For that to be true, then an NEC required earth ground must be missing. Relevant concepts were originally taught in elementary school science. And often get forgotten.

Lightning seeks earth ground. A path for a 20,000 amp electric surge is via a wooden church steeple destructively to earth. Wood is not a good conductor. So 20,000 amps creates a high voltage. 20,000 amps times a high voltage is high energy. Church steeple damaged.

Franklin installed a lightning rod. Now 20,000 amps is via a wire to an earthing electrode. High current creates near zero voltage. 20,000 amps times a near zero voltage is near zero energy. Nothing damaged.

Lightning seeks earth ground. A lightning strike to utility wires far down the street is a direct strike, incoming to every household appliance, destructively to earth. Appliances are not a good conductor. So lightning creates a high voltage. Lightning current times a high voltage is high energy. Appliances damaged.

For over 100 years, facilities that cannot have damage installed superior earthing connected low impedance (ie 'less than 10 feet') via one 'whole house' protector. Then high current creates near zero voltage. 20,000 amps times a near zero voltage is near zero energy. No appliance is damaged.

In your case, electricity was incoming on AC mains hot (black) wire. A best connection to earth was that picture causing wall and styrofoam damage. You did not earth that surge at the service entrance via a 'whole house' protector. So lightning was inside hunting for earth destructively. This time it found a best connection via that AC receptacle. Next time, what appliance or human will be a destructive connection to earth?

All cable and satellite cables are required (NEC, FCC, etc) to have protection - a low impedance (ie 'less than 10 feet') connection from each cable to a common (single point) earth ground. Telephone wires cannot connect directly. So each telco installs a 'whole house' protector - for free. All incoming wires have best protection IF you have properly installed and routinely inspected what only you are responsible for - the earth ground. And IF that connection to earth is that short.

AC electric wires connect a lightning strike far down the street directly into every receptacle and appliance. Because you obviously have not earthed a 'whole house' protector. Is every appliance damaged? Of course not. Lightning hunted for and found a best outgoing path to earth - the receptacle. Again, from elementary school science. To have damage means electricity must have both an incoming path and an outgoing path to earth. Every incoming wire must first connect to single point earth ground before entering. So that an outgoing path to earth is never inside the building.

An earth ground connection either hardwired directly (cable TV, satellite dish) or via a 'whole house' protector (telephone, AC electric). Otherwise everything inside a house remains at risk. Protection from direct strikes is routine. A lightning rod earthed to protect the building. All incoming utility wires earthed at the service entrance to protect contents of that building.

 

[joescho]

Had a customer that had a lightening strike on the chimney and it followed a wire in the wall to their closet and literally cooked all of the clothes on the metal hangers then blasted a hole in the siding 10 feet around before grounding out on the patio table umbrella. They were aeep the whole time and woke up to the smell of hair burning... Which was her fur coats on the closet.

yuk.

That's one of those where you wake up and ask what the **** happened here because I wouldn't be able to figure it out.