What is minimum safety distance from ground electrode that connected to lightning rod ?

Thread Starter

meowsoft

Joined Feb 27, 2021
470
What is minimum safety distance from ground electrode that connected to lightning rod ?, ground electrode is 12 meters long 3/4" copper bonded rod, and buried 60cm under soil surface (about 140 cm is insulated by PVC pipe), it is safe and good idea to work in 50cm radius from that places while rainy (my work area is elevated 40cm from soil surface and made from concrete, no direct soil surface) ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
470
IIRC the ground rod should be directly below the lightening rod in a vertical line.
Yes..., but what's about safe distance from ground rod ?, also in China that statement isn't required by local electric code, and my lightning rod is connected directly to ground rod with vertical line, with 70cm bare copper conductor, and my question again, it is safe to place radio receiver and wifi gun under about 100cm from lightning rods ?, with same galvanic pipe that support lightning rod
 

Yaakov

Joined Jan 27, 2019
3,520
There is no minimum safe distance. To protect that equipment you will need to ensure the lowest impedance path to ground is not through it. You can also put coaxial lightning protection on the feed line.

It is in a metal housing which is bonded to earth, what is inside will be the safest possible.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
470
There is no minimum safe distance. To protect that equipment you will need to ensure the lowest impedance path to ground is not through it. You can also put coaxial lightning protection on the feed line.

It is in a metal housing which is bonded to earth, what is inside will be the safest possible.
Are you thing my outdoor work area isn't safe while rainy nor thunderstorms ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
470
There is no minimum safe distance. To protect that equipment you will need to ensure the lowest impedance path to ground is not through it. You can also put coaxial lightning protection on the feed line.

It is in a metal housing which is bonded to earth, what is inside will be the safest possible.
My question is to protect human, working area is where I am work as engineer in outdoor, not to protect property
 

DickCappels

Joined Aug 21, 2008
7,742
Toward Alec_t's comment, You can have very large magnetic fields accompany lightning strikes and the magnetic fields can make the arc bend away from running in a straight line. I would want to be meters away with some good insulation between the ground wire and myself.
 

sagor

Joined Mar 10, 2019
479
I'm not an expert, but doing my tower grounding, most literature suggests the ground saturation (voltage) of a lightning hit reaches out to about 50 feet (15M), depending on soil conditions. This assumes a grounding system with multiple ground rods and radials. But again, this is not for all lightning hits, just your "average" one.
The EMP from a lightning hit can be induced into other wires nearby and still product unsafe levels. Any lightning rod should not be near any other equipment or masts.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
470
Toward Alec_t's comment, You can have very large magnetic fields accompany lightning strikes and the magnetic fields can make the arc bend away from running in a straight line. I would want to be meters away with some good insulation between the ground wire and myself.
OK... It is good idea to insulate ground rod at same level ?, currently I have insulate it with 2" PVC pipe for about 140cm, so I think is lightning voltage affect soil in 140cm deep, but is this good idea ?, and is my idea can make my ground capacity decrease significantly ?, or if it's good idea, can I add more deep insulation PVC pipe ?, I think about 200cm, so I am safe when lightning occurs because lightning current is absorbs about 240cm (I am 40cm top of soil) under soil surface, is I need to measure soil resistance between about 250cm deep testing rod and 20cm deep testing rod ?, I think if resistance is high I am very safe, because about 120cm under soil surface is clay and rocky, and about 200cm is sand and aquifer, I think rocky soil and clay can block lightning current from going to top layer soil surface when I am work, for make transformer winding, assembly electrical panel, and another stuff, also my working area is have metal roof also grounded with 35mm BC, and metal roof is about 280cm from concrete surface when I am working at outdoor

One more question..., I am have another lightning rods, that's down conductor (70mm BC) clamped in wall (outside), and my bed was only 10cm from wall (inside), wall thick is about 30cm and down conductor only 60cm from window with only 5mm glass, is this lightning protection safe or I need's to move my bed nor down conductor ?, I was scared if voltage surge brick the wall or window nor go inside wall, is that think can happen ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
470
Water Table is only 70cm about soil surface, but about 120cm is rocky soil and clay, and more deep about 200cm is soft soil, and my DIY boreholes is only about 540cm from soil surface, also primary boreholes is only about 850cm from soil surface
 

DickCappels

Joined Aug 21, 2008
7,742
OK... It is good idea to insulate ground rod at same level ?

No,but the ground lead (assuming you have a lead from your lightning rod to ground) should be arranged that sparks cannot jump from the lead to anything important. An insulating wall should offer some protection to things in the house, for example.

I have to defer to your local building and electrical codes since I don't formally know much about the subject.
 

trebla

Joined Jun 29, 2019
431
I remember when years ago lightning was stiking into power lines about one kilometer away from phone switch, then EMP from power line cable inducted energy to phone line cable which was laid parallel to power line about 20 meters away, so tens of subscriber line interfaces were burned out.
 

Delta Prime

Joined Nov 15, 2019
1,150
Hello there :)
My superiors have answered your specific questions by providing you options based upon information you provided.
The entire system of protection begins with the lightning rods.Lightning rods provide the atmosphere’s negative charge with a low-resistance path to the positive ions in the ground,by directing the electricity safely away from the building, tree, or tower they’re attached to, a lightning rod mitigates the damage likely to happen when millions of volts of electricity pass between the earth and the atmosphere,the shape, material, and design of a lighting rod matters,“In the world of lightning rod technology, sharp is better,”those negatively charged ions want the smoothest possible path to positive ions, so commercial lightning protection technology features pointy rods or radiating metal fingers. As the electrical current begins to flow through the lightning rod, it must be conducted away from the structure on which the rod is installed, usually through a cable terminating in a metal rod sunk into the ground to safely dissipate the electrical charge.You want a thick, highly conductive metal, like copper, to carry the current so it doesn’t arc to other materials and cause an explosion or fire
The concept behind lightning protection is simple, but the requirements for safe installation of a lightning rod are specific and require expertise , this is a life and death project. I believe something is getting lost in translation.:confused:
 
Last edited:

Tonyr1084

Joined Sep 24, 2015
6,269
Airplanes are struck by lightning all the time. Nobody inside is injured unless the lightning strikes the one running engine and knocks it out. Inside a metal enclosure you're protected by a principal called the Faraday Cage, where it conducts lightning around you.

I've seen video's of lighting strikes that blow trees apart and send wood shards everywhere. I was once inadvertently about 30 feet away from a tree when it was struck. We had been digging a trench for water, gas and sewage when a storm brewed up miles away. The CB radio used to communicate back and forth with the main lodge would hiss every time there was a local lightning strike. Maybe 30 or so miles away. One of the workers was counting the timing from the hiss to the thunder. When it approached 4 miles away he said "If your hair starts to stand on end get down on the ground or as low as possible. You're about to be hit by lightning." Not five minutes later our hairs were standing. Everybody jumped into the trench. As I went down into it I can swear lightning exited one wall of the trench into the opposite wall just feet away from my face. With logic and reasonable thinking - I don't think that actually happened. As I was going down into the trench I must have caught a glimpse of the lightning and my brain interpreted it as described. I don't recall any heat sensation or loud snap of an electrical arc.

But anywhere around a lightning storm - you don't want to be close.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
470
Hello there :)
My superiors have answered your specific questions by providing you options based upon information you provided.
The entire system of protection begins with the lightning rods.Lightning rods provide the atmosphere’s negative charge with a low-resistance path to the positive ions in the ground,by directing the electricity safely away from the building, tree, or tower they’re attached to, a lightning rod mitigates the damage likely to happen when millions of volts of electricity pass between the earth and the atmosphere,the shape, material, and design of a lighting rod matters,“In the world of lightning rod technology, sharp is better,”those negatively charged ions want the smoothest possible path to positive ions, so commercial lightning protection technology features pointy rods or radiating metal fingers. As the electrical current begins to flow through the lightning rod, it must be conducted away from the structure on which the rod is installed, usually through a cable terminating in a metal rod sunk into the ground to safely dissipate the electrical charge.You want a thick, highly conductive metal, like copper, to carry the current so it doesn’t arc to other materials and cause an explosion or fire
The concept behind lightning protection is simple, but the requirements for safe installation of a lightning rod are specific and require expertise , this is a life and death project. I believe something is getting lost in translation.:confused:
No.... Nothing Translation Losses
 
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