Telemetry pole grounding 2

[CuriousElectron]

Greetings,

I've got a steel mast that supports an antenna and a stainless steel control panel. I'd like to provide lightning protection for the pole and protect internal control equipment inside the control panel from lightning strikes. My thought is to install a lightning rod atop the pole and run down a dedicated ground wire down to ground rod. The steel pole will be installed on a concrete footing and will not be bonded to ground rod. From Ohm's law, the ground wire will offer a path of lowest resistant to ground for lightning energy. Since the pole is not bonded to ground rod, it will carry some energy, but hopefully not "significantly enough" to fry equipment inside the control panel. I'm also going to spec out lightning protection units to be located in the panel to make the lightning system protection more effective.

What you all think?

Best Regards,
EE

 

[VEBill]

Did you ever see my reply on the previous?

Grounding of Telemetry System

 

[waross]

Not much will survive a direct hit.
The anchor bolts and rebar will provide an effective Ufer ground for the tower. Ufer Ground
Please read the Wiki description.
The ground rod may have several times the resistance to ground as pole foundation, acting as a Ufer Ground.
One theory of lightning protection is that be the use of very sharp air terminals, most strikes can be avoided.
The theory is that the corona from the sharp air terminal reduces the field gradient in the vicinity of the air terminal and in most cases keeps the field gradient below the lightning strike value.
I welcome anyone who can provide a link to any information supporting or debunking this theory.
If I've been fed bad information, I'd like to know.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[CuriousElectron]

Hi VE1BLL,

Yes, I read your original response, and thanks for replaying to my previous post. You provided some useful info; however, I was looking for a simple yet effective solution. We're not going to install multiple rods just to protect a telemetry steel mast. It would be an overkill and nobody would make that investment...

Regards,
EE

 

[waross]

"I was looking for a simple yet effective solution."
Ufer Ground
Please read the Wiki description.
Add a bare copper wire embedded in the concrete for lower resistance to ground.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[VEBill]

OMG!! Polyphaser is back!!

Years ago, they were one of the companies offering (serious / professional grade) lightning protection products. They also offered a wealth of related technical information, backed-up with documented measurements and experience.

Then a few years ago, they sadly seemed to disappear. Just now I've discovered that they're back.

They have several dozen some whitepapers online. Historically, they've been a good source of detailed information.

 

[MacGyverS2000]

That Ufer ground seems so odd to me... so the resistance from copper to concrete is low, but what about concrete to ground? Should be just as high as direct copper to ground. Perhaps they're improving surface area by replacing large copper area with large concrete area?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[VEBill]

See Grounding & Materials white paper on Page 2.

Includes background and some explanation of Ufer grounding. The 'how it works' is on sheet 9.

 

[waross]

A combination of greater surface area and doping the surrounding earth to make it more conductive.
It is explained in the Wiki article linked above under Ufer Ground.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[waross]

Ufer Grounds
When building a new site, some radio installations do not take advantage of what is known as the Ufer
ground. This grounding technique can significantly reduce the overall ground system impedance. The
Ufer technique can be used in footings, concrete building floors, tower foundations and guy anchors.
The Ufer ground can be both a good lightning ground and safety ground. Under a ground fault condition,
more total energy will be conducted to ground than during a lightning strike, due to the longer time
required to clear the fault. Lightning has a very high peak energy, but the duration is very short. The Ufer
has been proven to handle both without failure.

Bill
--------------------
"Why not the best?"
Jimmy Carter