Is this a time bomb, or am I a dud?

[double-d]

We had quite a thunderstorm come through the other night, and it got me thinking, at 4:30 am.... does a stainless steel chimney liner or an Outside mounted stainless steel liner need to be grounded, to prevent lightning strikes? And if the liner was full of creosote, would that ignite?

 

[tfdchief]

We had quite a thunderstorm come through the other night, and it got me thinking, at 4:30 am.... does a stainless steel chimney liner or an Outside mounted stainless steel liner need to be grounded, to prevent lightning strikes? And if the liner was full of creosote, would that ignite?

double-d, the codes do not require it to be grounded/bonded, and in 33 years in the fire service, I have never seen that happen. Lightning is an unpredictable beast however and I have seen it energize anything and everything. But I have never seen a strike that I knew came in on a residential metal stack. By the way, if you have a blower on your wood stove, it is at least grounded/bonded with the equipment ground in the cord supplying the blower.

 

[jimbom]

A bare concrete slab in contact with earth can be a pretty good ground. In my case, a steel stove with steel pipe and chimney rests on the concrete in the basement. Certain moisture conditions - bingo. A guy up hill on the flat was killed in his garage. Lying on his back on the concrete garage floor under his truck. Electrocuted by his shop light current passing through his body to the floor.

If I lived on top of spooky hill in high lightning climate, I might consider a lightning protection system. My guess is the lightning protection expert would install an an air terminal for the chimney, but not grounded to the chimney. I am probably wrong about this, but it seems to me the prudent approach. In other words, the design goal would be to lead a lightning strike safely to ground and keep it from passing through the structure.

 

[tfdchief]

In other words, the design goal would be to lead a lightning strike safely to ground and keep it from passing through the structure.

Good Luck :smirk:

 

[firefighterjake]

Seems like this question is asked every Spring or early Summer . . . best answer I've seen is that lightning is pretty unpredictable . . . and probably has hit some chimneys . . . but has also hit many a roof peak or nearby tree too . . . I wouldn't worry too much about this unless I was living high on an exposed hill with nothing else taller than my home nearby.

 

[Backwoods Savage]

We've had lightning strike many trees near us and even struck a transformer on the pole but have never had it strike the chimney....at least as far as we know. I'd bet it would surely make a loud CRACK if it ever did. Personally, I would never worry about it happening.

 

[PJF1313]

We've had lightning strike many trees near us and even struck a transformer on the pole but have never had it strike the chimney....at least as far as we know. I'd bet it would surely make a loud CRACK if it ever did. Personally, I would never worry about it happening.

And, if you where home at the time, your mouth would taste like you just ate a lemon tree!

Talking from experience - lightning struck a tree about 25 yards from the shop a few summers ago.
Flash-Bang = INSTANT
Sour taste lasted for a few hours!
Old Oak = Scattered, smoldering splinters; fastest drying cord I've ever seen ;-) (burned that winter!)

 

[Wood Heat Stoves]

I've never seen that happen and I've been in the business for over 30 years. I could see how it might happen, so I wouldn't want to tell you not to ground it if you're concerned, but I would worry more about keeping your chimney clean and burning dry, seasoned wood to avoid a regular chimney fire. That's more likely.

 

[Backwoods Savage]

That is interesting. I've had lightning strike very close many times but never noticed a bad taste. I hope I'm never any closer to the lightning either.

 

[fbelec]

if you think you might get hit, ground it. it will cost about 25 dollars and some beating on a 8 foot ground rod with a sledge hammer or rotary hammer to make it easy. it is possible that it get hit. the wind is what charges things up. if the wind charged your chimney positive and the cloud over head is charged negative and looking for a place to dump that charge and the chimney is the closest positive charge it will seek it out. peoples brick chimney get hit all the time. what you will need is a 8 foot ground rod and the clamp that is used on the top of the rod sticking out of the ground called a acorn and some #6 ga. copper wire to run from the rod to the chimney at the chimney attach a wire lug that will fit the #6 wire and your done.

 

[Mt Ski Bum]

I've been extremely close to several lightning strikes- close enough for instantaneous flash-&-boom, & have never experienced a sour taste either...

 

[tfdchief]

if you think you might get hit, ground it. it will cost about 25 dollars and some beating on a 8 foot ground rod with a sledge hammer or rotary hammer to make it easy. it is possible that it get hit. the wind is what charges things up. if the wind charged your chimney positive and the cloud over head is charged negative and looking for a place to dump that charge and the chimney is the closest positive charge it will seek it out. peoples brick chimney get hit all the time. what you will need is a 8 foot ground rod and the clamp that is used on the top of the rod sticking out of the ground called a acorn and some #6 ga. copper wire to run from the rod to the chimney at the chimney attach a wire lug that will fit the #6 wire and your done.

fbelec, being an electrician I know that you are aware that if you are going to do this, the NEC requires that you must also bond this ground rod to the building or structure grounding electrode system. Additionally, NFPA 780-4.8.9 requires a strike termination device on thin metal chimneys. Just thought we ought to mention it.

 

[Intheswamp]

if you think you might get hit, ground it. it will cost about 25 dollars and some beating on a 8 foot ground rod with a sledge hammer or rotary hammer to make it easy. it is possible that it get hit. the wind is what charges things up. if the wind charged your chimney positive and the cloud over head is charged negative and looking for a place to dump that charge and the chimney is the closest positive charge it will seek it out. peoples brick chimney get hit all the time. what you will need is a 8 foot ground rod and the clamp that is used on the top of the rod sticking out of the ground called a acorn and some #6 ga. copper wire to run from the rod to the chimney at the chimney attach a wire lug that will fit the #6 wire and your done.

fbelec, being an electrician I know that you are aware that if you are going to do this, the NEC requires that you must also bond this ground rod to the building or structure grounding electrode system. Additionally, NFPA 780-4.8.9 requires a strike termination device on thin metal chimneys. Just thought we ought to mention it.

+1 on the first part of tfd's remark...didn't know about the second part.

Does the requirement for a strike termination device apply to ss liners in brick chimneys where the tallest point is the metal cap? There's trees taller than the chimney around my house and might pick up the static discharge before it got to the chimney cap but still I'm curious about the code. We had the transformer beside the house lit up before, quite a light show, but that was from induced voltage on the line rather than a direct strike.

Ed

 

[tfdchief]

if you think you might get hit, ground it. it will cost about 25 dollars and some beating on a 8 foot ground rod with a sledge hammer or rotary hammer to make it easy. it is possible that it get hit. the wind is what charges things up. if the wind charged your chimney positive and the cloud over head is charged negative and looking for a place to dump that charge and the chimney is the closest positive charge it will seek it out. peoples brick chimney get hit all the time. what you will need is a 8 foot ground rod and the clamp that is used on the top of the rod sticking out of the ground called a acorn and some #6 ga. copper wire to run from the rod to the chimney at the chimney attach a wire lug that will fit the #6 wire and your done.

fbelec, being an electrician I know that you are aware that if you are going to do this, the NEC requires that you must also bond this ground rod to the building or structure grounding electrode system. Additionally, NFPA 780-4.8.9 requires a strike termination device on thin metal chimneys. Just thought we ought to mention it.

+1 on the first part of tfd's remark...didn't know about the second part.

Does the requirement for a strike termination device apply to ss liners in brick chimneys where the tallest point is the metal cap? There's trees taller than the chimney around my house and might pick up the static discharge before it got to the chimney cap but still I'm curious about the code. We had the transformer beside the house lit up before, quite a light show, but that was from induced voltage on the line rather than a direct strike.

Ed

Ed, NFPA 780 simply says that all chimneys shall have strike termination devices. It should be understood however, that the NFPA Standards, are just that, standards. They are not required unless adopted by a jurisdiction or referenced by an adopted code in a jurisdiction. NFPA 780 is fairly complex and should be referenced in its entirety if lightning protection is the goal. Even trees are covered :exclaim: Steve

 

[woodchip]

I've been extremely close to several lightning strikes- close enough for instantaneous flash-&-boom, & have never experienced a sour taste either...

Many years ago I was very close to a lightning strike and never noticed a sour taste, but everything went fizzy and tingly.

Not something I'm in a hurry to repeat

 

[fbelec]

if you think you might get hit, ground it. it will cost about 25 dollars and some beating on a 8 foot ground rod with a sledge hammer or rotary hammer to make it easy. it is possible that it get hit. the wind is what charges things up. if the wind charged your chimney positive and the cloud over head is charged negative and looking for a place to dump that charge and the chimney is the closest positive charge it will seek it out. peoples brick chimney get hit all the time. what you will need is a 8 foot ground rod and the clamp that is used on the top of the rod sticking out of the ground called a acorn and some #6 ga. copper wire to run from the rod to the chimney at the chimney attach a wire lug that will fit the #6 wire and your done.

fbelec, being an electrician I know that you are aware that if you are going to do this, the NEC requires that you must also bond this ground rod to the building or structure grounding electrode system. Additionally, NFPA 780-4.8.9 requires a strike termination device on thin metal chimneys. Just thought we ought to mention it.

yes. thanks, it was late when posting. just bring a #6 back to the panel's ground bar. not to the meter ground. power company doesn't like that. even thou it still connected at the panel. bonding issues can be different depending on the town. at least here anyway. i don't have the nfpa 780 code book just the nec nfpa 70 code book. if you are lucky enough to have the service ground rod below the antenna then there is no need to pound a new. when i was a kid i got hit with a static charge on a cb antenna that was not bonded or grounded. pickup the antenna cable a foot away from the end and had a spark hit me to discharge itself to the steam radiator. ouch. had to go wipe after that one.

 

[tfdchief]

if you think you might get hit, ground it. it will cost about 25 dollars and some beating on a 8 foot ground rod with a sledge hammer or rotary hammer to make it easy. it is possible that it get hit. the wind is what charges things up. if the wind charged your chimney positive and the cloud over head is charged negative and looking for a place to dump that charge and the chimney is the closest positive charge it will seek it out. peoples brick chimney get hit all the time. what you will need is a 8 foot ground rod and the clamp that is used on the top of the rod sticking out of the ground called a acorn and some #6 ga. copper wire to run from the rod to the chimney at the chimney attach a wire lug that will fit the #6 wire and your done.

fbelec, being an electrician I know that you are aware that if you are going to do this, the NEC requires that you must also bond this ground rod to the building or structure grounding electrode system. Additionally, NFPA 780-4.8.9 requires a strike termination device on thin metal chimneys. Just thought we ought to mention it.

yes. thanks, it was late when posting. just bring a #6 back to the panel's ground bar. Yes if it is the service disconnect. not to the meter ground. power company doesn't like that. even thou it still connected at the panel.[/color] bonding issues can be different depending on the town. at least here anyway. i don't have the nfpa 780 code book just the nec nfpa 70 code book. if you are lucky enough to have the service ground rod below the antenna then there is no need to pound a new.Here would be better as you can attach to the ground rod (with a separate clamp) or the grounding electrode conductor. when i was a kid i got hit with a static charge on a cb antenna that was not bonded or grounded. pickup the antenna cable a foot away from the end and had a spark hit me to discharge itself to the steam radiator. ouch. Ouch is right, glad you are ok. had to go wipe after that one.

 

[jimbom]

In other words, the design goal would be to lead a lightning strike safely to ground and keep it from passing through the structure.

Good Luck :smirk:

You know the drill. "The contractor is responsible for submitting drawings and specifications for the installation that conform to NFPA 780 and shall obtain UL approval." TA DA. My job is done.

 

[tfdchief]

In other words, the design goal would be to lead a lightning strike safely to ground and keep it from passing through the structure.

Good Luck :smirk:

You know the drill. "The contractor is responsible for submitting drawings and specifications for the installation that conform to NFPA 780 and shall obtain UL approval." TA DA. My job is done.

Yep

 

[fbelec]

i hope this link works. it's about what this thread is about.
for you old timers of this forum it's in the town elk worked in.
http://www1.whdh.com/news/articles/local/12004077582758/wrentham-home-catches-fire-during-storm/