Bad Lightning Protection?

[formula1]

i work on a large property where the main house has lighting protection, instead of the wires from the rods going down the outside of the building they go down inside the walls this house also has a copper roof has anyone seen the damage this could cause if the house was hit by lighting

 

[LLSolutions]

I have ran the lightning protection inside a building but it was in PVC and only to get from the roof then into the block. As for the copper roof I would bond the lowest edges to one of the down leads. In Lightning protection theory the roof should never get hit only the higher air terminals.

 

[formula1]

funny guys funny this is what happens when you are running out the door

 

[bphgravity]

Like every electrical installation, there are design options which need to be taken into consideration, but still remain compliant with the applicable code. The NFPA 780 governs lightning protection systems.

While from a purists view, it is always best to keep the LPS components on the outsdie of the structure, running down conductors through a building, through the interior of a building, or using the building materials themselves is a recognized and accpetalce method for reaching the earth.

Invest some time reviewing the NFPA 780...

 

[charlietuna]

Lightning doesn't care as long as there are no sharp turns in the grounding down leads and properly terminated onto the ground grid !

 

[brian john]

Not disagreeing with running inside a structure, BUT i always felt that the conductor could be heated and possible result in a fire negating the advantage of the LPS

 

[mdshunk]

Not disagreeing with running inside a structure, BUT i always felt that the conductor could be heated and possible result in a fire negating the advantage of the LPS

That might be why all of the inside systems I can remember seeing (maybe 3) seem to have grossly oversized down conductors.

 

[Pierre C Belarge]

Down conductor placement is important, whether inside the building or outside of the building, the more important aspect of placement is in regards to the proximity of other metallic grounded elements of the building.

 

[ron]

I have not seen the associated damage, but I always theorized that the magnetic fields induced by the electrons traveling on the conductor built into the exterior wall would make the conductor move violently, thus damaging the wall. If the wall was required for structural support, that may be bad.

I saw bus bars move in a video of a short circuit test.

 

[bphgravity]

Magnetic fields are very impressive. I have been told that MRI and other magnetic imagining machines can play havoc on a buildings structural system if not properly protected.

Lightning is practically an instantaneous event. While huge magnetic fields are created, it is the induced current in those magnetic fields that is the greater concern. BONDING is the key to eliminating this occurrence.

 

[brian john]

I was involved in a project where the down conductor was routed next to a wall on the opposite side of the wall was telco equipment, this site was constantly taking lightning hits and every time they took a hit the site telco system went down. We relocated the down conductor and not one failure in 7 years even though there have been reported lightning hits.

 

[weressl]

Not disagreeing with running inside a structure, BUT i always felt that the conductor could be heated and possible result in a fire negating the advantage of the LPS

Right you are!

 

[formula1]

that is what i believe ive seen what lighting can do to romex and sheetrock running lighting protection inside the walls just seems plain dumb to me