Interesting oddity - any opinions welcome

[LarryFine]

Hey, gang, I was asked this question on my website, and I would like to hear any opinions you may have:

Hi, Every time we have a thunderstorm and lightning, I hear a short buzz sound then see a flash in my return vent in my upstairs hallway immediately before I hear the boom of thunder and see lightning. This is starting to worry me because it seems dangerous. The HVAC people came and looked and said everything seemed fine. I have called a couple of electricians and they have no idea what this could be. Do you have any ideas?

My first thought is an ungrounded roof-top antenna, and static voltage build-up.

 

[stickboy1375]

Maybe a electronic air cleaner?

 

[Dennis Alwon]

..... immediately before I hear the boom of thunder and see lightning.

I solved the problem. Lightning should come first then you should hear the boom.:grin:

Seriously, this is an odd phenomena. Sounds like maybe someone is pulling your leg. The reason I say this is because I am trying to imagine how this can happen every time there is lightning. That means their home gets hit all the time.

I am with you on the roof top deal. Perhaps they have lightning rods on the roof that are not grounded. Why would it flash in the duct??? Maybe the ground wire is loose in the attic and is touching the duct.

 

[cadpoint]

Get the bugs out of the Duct ...

Either the odds that they heard the well effect of The Hive, burping due to the thunder, or a loose neutral .... on the damper flap ... :roll:

Well technically there getting hit too ...

 

[stickboy1375]

Sounds like a call to Myth Busters...

 

[Pierre C Belarge]

Larry
Odd indeed. It just does not seem possible, but stranger things have happened.
I would respond with a comment that they should try to record the event with the next storm on video camera. Then you may be able to see what is really happening.
Some people stress out over things that really do not exist sometimes.

 

[boater bill]

Where is the closest window to this vent?

Maybe it is reflecting the flash of the lightning?
Otherwise their ductwork may be the path to ground for their lightning protection.

 

[ELA]

Does their hair stand on end also ?

I agree with your static suspicion. Is it possible the metal duct is isolated from ground, this could easily be checked. If so static could build up and arc to a nearby ground (pipe or wire?)
If the duct is isolated then grounding it could solve the mystery.

Does seem strange that they could experience such strong electro-static fields during every storm.

 

[catchtwentytwo]

Hi, Every time we have a thunderstorm and lightning, I hear a short buzz sound then see a flash in my return vent in my upstairs hallway immediately before I hear the boom of thunder and see lightning. This is starting to worry me because it seems dangerous. The HVAC people came and looked and said everything seemed fine. I have called a couple of electricians and they have no idea what this could be. Do you have any ideas

I had something like this occasionally happen at my house but it involved my kitchen sink. Pretty sure it was "jumping" from the cast iron vent pipe to the copper water piping or galvanized drain line. I have city water with a metallic main and a ground rod poured into the basement slab.

There was a very tall Tulip Tree with a branch close to my roof. When branch was removed, the situation stopped.

 

[iwire]

any opinions welcome

A little to much partying going on in that house.

 

[Cavie]

It is static discharge. A very good friend of mine learned of this on his sailboat this summer on Lake Michagin. A storm was approching and as he reached down to lift the motor up, He got a VERY larg electric shock. The kind given off by a spark plug in an automobile. He was touching the safty rail and the motor. He is an Auto Electronics Instructor for the State of Ill. So I do beleive what he tells me. His sailing buddy laughed at him so he made HIM pull up the motor an he too was shocked. Static electricity is building up on your duct system prior the the lightning flash. Ground the duct system and let me know if you see this problem again.

 

[ghostbuster]

It is static discharge. A very good friend of mine learned of this on his sailboat this summer on Lake Michagin. A storm was approching and as he reached down to lift the motor up, He got a VERY larg electric shock. The kind given off by a spark plug in an automobile. He was touching the safty rail and the motor. He is an Auto Electronics Instructor for the State of Ill. So I do beleive what he tells me. His sailing buddy laughed at him so he made HIM pull up the motor an he too was shocked. Static electricity is building up on your duct system prior the the lightning flash. Ground the duct system and let me know if you see this problem again.

Just to add to the above post.

A friend that owns a resort with large motorboats to rent,has noticed the motor electronics on some of the boats gets "fried" after a lighning storm.He now tilt lifts the motors out of the water before a storm arrives.He no longer has failures.

 

[quogueelectric]

Return vent

Return vent

Is this vent an open return attic plenum vent where any flash in the attic will be seen from the vent or is it tied directly to the bottom of the air handler where the flash is enclosed in the air handler itself.