Hi.
A tree near the edge of my roof is twice taller than the roof ridge height.

Would attaching 1/2" copper pipe or tubing from the top of the tree all the way down by the trunk to ground by its roots work instead of installing a 'normal' rod system on the roof ?

What if instead, 1/2" solid iron bar like concrete reinforcement uses ?

 

Lightning occurs when ground streamers (heavily ionized paths) hit oppositely charged streamers from a cloud. When they connect, BOOM - a lightning bolt is created. A lightning rod works by shunting the ionized paths coming off your structure back to ground. The streamers aren't visible to the naked eye, but they can be captured on film.

For the system to be effective in a tree, every branch would need to have a rod in it.

 

brief blurb: http://pallensmith.com/2015/02/05/lightning-rods-for-trees/

 

There was an old school theory called "cone of protection". Supposedly, if you ground a high point, a cone of area beneath that point should be protected from lightning strikes.

Personally, I would lightning rod the house.

If the tree is close to the house, you might consider lightning roding the tree for added protection. One wire wrapped at top. Install ground rod away from tree root. i.e don't pound rod in root.

 

From what I have read, a lightning rod helps safely direct a strike to ground through the heavy ground wire into the ground rod, but it generally has little effect on whether a strike will occur or not.
Do you have an article that says otherwise?

As far as a tree goes, I would think adding a rod at the very top of the tree with a heavy wire or copper tube to a good ground rod at the tree base should provide a good path for any strike.
You want low resistance so copper is much better than steel.
Of course copper pipe is an alloy so it may have significantly higher resistance than copper wire.
You could measure its resistance by passing a couple amps through a length of it and measure the voltage drop.
Some lightning rod cable sold by a vendor stated it consisted of a woven pattern of 32 17-gauge copper wires, which calculates to about 500μΩ per meter.
According to this, the maximum space between lightning rods should be 20 feet (cone of protection?).

 

This is an excellent explanation of how lightning rods prevent lightning, along with a small experiment that shows a "lightning rod" working in real life:

 

This is an excellent explanation of how lightning rods prevent lightning, along with a small experiment that shows a "lightning rod" working in real life:

Interesting.
I wonder if it works that well to discharge the huge amount of charge in a cloud over a distance of several thousand feet from the charged cloud to the lightning rod on a buildings roof.
If it truly worked that way to prevent lightning strikes, they you wouldn't need the very large copper wire they use to tie a lightning rod to ground since the ionization current should be quite small compared to the strike current.

 

It would be an interesting data point to see how often lightning actually strikes a lightning rod. In regards to the braided copper wire used for lightning rods; the handful of buildings that I've noticed this on, they usually have one or two large copper straps that feet a larger number of spikes on the roof, so one wire feeds many lightning rods. Maybe it's not necessary to discharge the entire cloud, but only necessary to discharge an area above the lightning rod large enough to prevent a conductive pathway to the cloud from developing, for lack of a better way to explain it.

 

Hi.
A tree near the edge of my roof is twice taller than the roof ridge height.

Would attaching 1/2" copper pipe or tubing from the top of the tree all the way down by the trunk to ground by its roots work instead of installing a 'normal' rod system on the roof ?

What if instead, 1/2" solid iron bar like concrete reinforcement uses ?

A lightning strike turns tree sap into superheated steam - in extreme cases, the tree trunk can literally explode. If the house is close enough to catch some damage, there might be a case for protecting the tree.

Take care what metal you use - copper might poison the tree, some other metals aren't much better.

 

I second the use of copper wire over steel rebar. I wonder what the effect of a 10,000+ amp strike on the steel rebar would do to the tree (RE: cook it?). Ian is correct about copper poisoning a tree, but as long as you keep copper out of the tree (or the tree growing around a copper wire), using copper is best.

 

The points on the lightning rod count.

The tree in my back yard is like 4 feet in diameter and is way above the house. The TV antenna is grounded, but not lightning protected. There is also the HV primary that runs near the tree too in the back of the yard. There is also a cyclone fence around the perimeter. Aluminum siding and an aluminum gutter. The siding on one side of the house is likely grounded.

It's just really tough thinking about how to do the lightning protection because a driveway is the "closest ground". Driving of ground rods could crack the foundation and could be a tripping hazard. In one direction, there is too much distance because of a porch.

 

I second the use of copper wire over steel rebar. I wonder what the effect of a 10,000+ amp strike on the steel rebar would do to the tree (RE: cook it?). Ian is correct about copper poisoning a tree, but as long as you keep copper out of the tree (or the tree growing around a copper wire), using copper is best.

Most overhead power cables are steel rope core enclosed by multiple strands of aluminium wire.

Aluminium isn't as good conductor as copper, but the light weight is required for overhead cables - and the steel core is required to make it strong enough.

Exposed aluminium immediately grows an oxide skin in contact with air, the toxicity might not be much better than copper, but the oxide skin reduces exposure.

 

Aluminum does have lower conductivity than copper on a volume basis but I believe it has a higher conductivity on a weight basis.
That's why it make a lighter power line cable.

 

Resistivity and conductivity likely confuses people. Here's a table of resistivities for some metals.

With Silver, Copper, Aluminum and the same diameter and length, copper would have a lower resistance than aluminum and silver would beat copper. You see silver plated tubes as conductors in RF stuff.

R=pL/A where p is the resistivity, A is cross-sectional area and L is the length. Watch units.

 

A lightning strike turns tree sap into superheated steam - in extreme cases, the tree trunk can literally explode. ....<snip>...

This happened in my back yard. Lightning hit a pine tree and bark was sprayed across the back yard, and missing in sections from the tree. That tree died, as did a tree about 15' away from it. I'm guessing their roots were intertwined.

 

This happened in my back yard. Lightning hit a pine tree and bark was sprayed across the back yard, and missing in sections from the tree. That tree died, as did a tree about 15' away from it. I'm guessing their roots were intertwined.

I vaguely remember reading somewhere that a large proportion of people killed or injured sheltering under trees; are speared by splinters as the trunk bursts.

There is also a ground potential radiating from the base of the tree - if your feet are apart; your balls light up (women have a built in spark gap).