Previous in Forum: Generator Reactance   Next in Forum: Earthing Truck
Close
Close
Close
50 comments
Active Contributor

Join Date: Mar 2011
Posts: 14

Connecting Lightning System With Earthing/Grounding System

04/01/2014 10:25 AM

I had a discussion with several electrical engineers about the connection between lightning and grounding system. some of them stated that it is recommended to connect both systems while others did not recommend !! what do you recommend and why ??

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Guru

Join Date: Jul 2007
Location: Commissariat de Police, Nouvions, occupied France, 1942.
Posts: 2599
Good Answers: 76
#1

Re: Connecting lightning system with earthing/grounding system

04/01/2014 10:46 AM

Let's put it this way. Would you be happy with lightning bolts coming out of your domestic socket outlets, Uncle? If not, why not?

__________________
Good moaning!
Register to Reply
Guru

Join Date: Oct 2008
Posts: 42329
Good Answers: 1666
#2

Re: Connecting lightning system with earthing/grounding system

04/01/2014 11:45 AM

If they told you they were electrical engineers, they're lying to you.

They sound more like dung peddlers.

Register to Reply
Guru

Join Date: Oct 2008
Posts: 42329
Good Answers: 1666
#7
In reply to #2

Re: Connecting lightning system with earthing/grounding system

04/01/2014 6:16 PM

Sorry, I was too harsh in my last post, referring to these "engineers" as dung peddlers.

My apologies to all dung peddlers.

Register to Reply Score 1 for Good Answer
Power-User
Engineering Fields - Power Engineering - New Member

Join Date: Feb 2011
Location: Pakistan
Posts: 126
#14
In reply to #7

Re: Connecting lightning system with earthing/grounding system

04/02/2014 5:12 AM

Lyn, I agree with you...and I quote if it would earn us any scoring credit...Hehehehe... "Lightning protection systems and it's earth electrodes in pits must be totally separate from the earthing system intended wholly solely for electrical installation (LV Panel, SMDB, DB etc.). The pits with electrodes in it must be seven meters apart from the pits for electrical services (Installation)..."

__________________
--
Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#15
In reply to #14

Re: Connecting lightning system with earthing/grounding system

04/02/2014 5:27 AM

That sounds contrary to the installation practices and standards I'm compelled to adhere to.

Do you have a citation for that quote?

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Power-User
Engineering Fields - Power Engineering - New Member

Join Date: Feb 2011
Location: Pakistan
Posts: 126
#20
In reply to #15

Re: Connecting lightning system with earthing/grounding system

04/02/2014 8:23 AM

Yes, I do have a citation for that quote: The Electricity Wiring Regulations 2007 ...issued by the Regulation and Supervision Bureau ...Abu Dhabi, United Arab Emirates;Chapter 6. Earthing ... 6.8 Lightning protection ...

__________________
--
Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#28
In reply to #20

Re: Connecting lightning system with earthing/grounding system

04/02/2014 7:50 PM

Thanks

I'd like to study that one...

You wouldn't happen to have a URL for that?

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Guru

Join Date: Mar 2012
Location: Out of your mind! Not in sight!
Posts: 4424
Good Answers: 107
#30
In reply to #28

Re: Connecting lightning system with earthing/grounding system

04/02/2014 9:08 PM
__________________
Common Sense Dictates
Register to Reply
Power-User
Engineering Fields - Power Engineering - New Member

Join Date: Feb 2011
Location: Pakistan
Posts: 126
#32
In reply to #28

Re: Connecting lightning system with earthing/grounding system

04/03/2014 2:29 AM

>You wouldn't happen to have a URL for that?
Here is a link or two ;)
http://rsb.gov.ae/en/publications/detail/electricity-wiring-regulations-third-edition1
http://www.ecomanonline.com/Brochures/71520101254469375000.pdf

__________________
--
Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#34
In reply to #32

Re: Connecting lightning system with earthing/grounding system

04/03/2014 4:28 AM

Thanks abasins,

I already located and downloaded a copy of the standard you cited.

You didn't quote the standard completely. The actual wording is:

6.8.3 Lightning protection systems must be designed,

constructed and maintained in accordance with BS EN

62305, except that the lightning protection system is not

to be bonded to the Installation Main Earth Terminal.

Basically saying to follow BS EN 62305 (which does require bonding) but don't bond it here in Abu Dhabi please.

The requirement to bond seems to be subject to local jurisdiction. Hmmmm.

Me, I'll keep following the Ozzy standards unless directed by my client to deviate and therefore it's their rap, or my client specifies the use of or compliance with another contrary standard.

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Power-User
Engineering Fields - Power Engineering - New Member

Join Date: Feb 2011
Location: Pakistan
Posts: 126
#35
In reply to #34

Re: Connecting lightning system with earthing/grounding system

04/03/2014 5:15 AM

Wal writes:

>Thanks abasins,

>I already located and downloaded a copy of the standard you cited.

>You didn't quote the standard completely. The actual wording is:

> <Stuff Deleted>

>Basically saying to follow BS EN 62305 (which does require bonding) but don't bond it >here in Abu Dhabi please.

>The requirement to bond seems to be subject to local jurisdiction. Hmmmm.

>Me, I'll keep following the Ozzy standards unless directed by my client to deviate >and therefore it's their rap, or my client specifies the use of or compliance with >another contrary standard.

I quote:
6.8.3 Lightning protection systems must be designed, constructed and maintained in accordance with BS EN 62305, except that the lightning protection system is not to be bonded to the Installation Main Earth Terminal. [See clause 5.7.6 for requirements for protection against over- voltages.]
If you would read the clause 5.7.6...It is for protection against over voltages...Lightning surge carries very high current and very high voltage which would seem extremely dangerous to be bonded to the installation earthing system. BTW, somewhere under this thread someone is talking about electronics equipment earthing...Well, for that there is a "functional earthing/grounding"...:)

__________________
--
Register to Reply
Power-User
Engineering Fields - Power Engineering - New Member

Join Date: Feb 2011
Location: Pakistan
Posts: 126
#36
In reply to #20

Re: Connecting lightning system with earthing/grounding system

04/03/2014 5:37 AM

It just came out.

The Electricity Wiring Regulations (Third Edition) ...March 2014...and it is downloadable from the same given link....It says:

6.8 Lightning protection

6.8.1 Lightning protection systems must be designed, constructed and maintained in accordance with BS EN 62305.

6.8.2 Where practicable, a minimum distance of 7 m must be provided between lightning protection Earth Electrodes and the Electrical Installation Earth Electrodes.

6.8.3 Surge protective devices must be used at the Connection Point for Premises with a lightning protection system. These shall be installed typically at the Main Distribution Board. See Guidance note G10.

__________________
--
Register to Reply Score 1 for Good Answer
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#37
In reply to #36

Re: Connecting lightning system with earthing/grounding system

04/03/2014 5:48 AM

So, bond the grounds and SPDs are mandatory?

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Power-User
Engineering Fields - Power Engineering - New Member

Join Date: Feb 2011
Location: Pakistan
Posts: 126
#38
In reply to #37

Re: Connecting lightning system with earthing/grounding system

04/03/2014 7:19 AM

Wal writes:
>So, bond the grounds and SPDs are mandatory?
A) Accordance with BS EN 62305 ...If the code implies that then...However; B) 6.8.2 Where practicable, a minimum distance of 7 m must be provided between lightning protection Earth Electrodes and the Electrical Installation Earth Electrodes.
And then; C) 6.8.3 Surge protective devices must be used ...

__________________
--
Register to Reply
Guru
United Kingdom - Member - New Member

Join Date: Aug 2010
Location: Resting under the Major Oak
Posts: 4347
Good Answers: 180
#19
In reply to #14

Re: Connecting lightning system with earthing/grounding system

04/02/2014 7:49 AM

I think you'll find it's 8 metres between MV and LV pits where the resistance of the LV pit is ≥ 2Ώ. <2Ώ they can be linked.

__________________
The reports of my death are greatly exaggerated.
Register to Reply
6
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15287
Good Answers: 940
#3

Re: Connecting lightning system with earthing/grounding system

04/01/2014 1:23 PM

It all depends on your local codes and the semantics on what people are saying. A lightning protection system must be connected to earth somewhere or no protection can be obtained. Similarly the grounding system of a location must be connected to earth or it won't be a grounding system. Now how these two systems get connected to the same equi-potential point (earth) is the critical point that can only be settled by following your local codes.

__________________
"Don't disturb my circles." translation of Archimedes last words
Register to Reply Good Answer (Score 6)
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#16
In reply to #3

Re: Connecting lightning system with earthing/grounding system

04/02/2014 5:50 AM

The perfect answer!!!!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Canada - Member - If there is a way to screw someting up, there is someone to do so! Safety - Hazmat - New Member

Join Date: Mar 2007
Location: Iqaluit, NU. Canada
Posts: 1852
Good Answers: 140
#4

Re: Connecting Lightning System With Earthing/Grounding System

04/01/2014 3:35 PM

It is a requirement of both the Canadian and US codes that "all" grounding systems that terminate on a ground electrode have their ground electrodes interconnected. This is to ensure that no potential difference can exist on one ground system verses another.

But... the advice from Redfred is spot on. Read your local code and follow it!

__________________
Joe Contractor to Electrical Inspector, "What do you mean you are going to make me follow the code?".
Register to Reply
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21012
Good Answers: 783
#5
In reply to #4

Re: Connecting Lightning System With Earthing/Grounding System

04/01/2014 4:27 PM

What constitutes "one" grounding system? Surely that rule doesn't require that all grounding systems shall be interconnected?

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Guru

Join Date: Dec 2010
Posts: 1895
Good Answers: 44
#11
In reply to #5

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 2:13 AM

Yes...yes they do....if you follow the IEEE and NFPA 70

Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#12
In reply to #11

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 3:32 AM

...or follow AS/NZS 1768:2007

Bond the lot.

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Guru

Join Date: Nov 2007
Location: Eastern Arizona mountains on Route 666 about a mile from God's country
Posts: 1676
Good Answers: 122
#21
In reply to #4

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 10:30 AM

No longer true in the USA.

We now have different grounding requirements that are dependent on the type of equipment installed and the location.

Most DCS and other communication systems are required to be connected to a separate ground system with a separate ground well/electrode.

Most lightning protection systems are now required to be installed with the discharge ground electrodes physically separate to the building and equipment ground system electrodes.

This is based on the ideology of providing a path for the millions of volts presented by a lightning strike to be shunted arround the building and/or equipment without entering the equipment ground system and therefore exposing the electrical/electronic equipment components to high voltage.

I am not confident in this theory alone and based on my experience, I believe the best method of lightining protection is to combine separate a lightning grounding system along with creating a neutralizing cloud in the air above the building and/or equipment.

About twelve (12) years ago I was tasked with solving lightning strike damage control at a remote site that was experiencing 25 -30 strikes per month during the monsoon season. Although I was reluctant at following the advice of one of my older mentors, we combined a separate lightning ground system with adding a single-point, extendable lightning rod installed ten (10) feet below grade with a copper electrode base and a 4/0 copper conductor up to the rod point that extended ten feet above the highest elevation of the equipment and buildings at the site. As we raised the lightning rod up into the air the corona activity increased to the point at which we were had to stop due to the electrical shock being experienced by the workers. Raising the rod to the final elevation of 40 feet took place over three days as we had to allow the current flow to dissipate for every 10-15 feet of elevation. After the installation was complete the corona phenomonon displayed at the top of the lightning rod was awesome for a period of six (6) days especially at night even though there were no clouds pressent. At the middle of the seventh day the corona activity stopped. There has not been any lightning damage at that site since the system was installed and the actaul number of recorded lightning strikes is now less than three per year.

I have no way of knowing if this methodology will work at every location however to-date it has worked well for me on my projects.

__________________
They said; "Brain size?" I heard; "Train size?" so I said: "I'll take a small one, thank you."
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#25
In reply to #21

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 11:15 AM

I like your post.....it fits in with both my theory and limited practice, thanks.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Power-User
Engineering Fields - Power Engineering - New Member

Join Date: Feb 2011
Location: Pakistan
Posts: 126
#26
In reply to #21

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 11:39 AM

>No longer true in the USA.

>We now have different grounding requirements that are dependent on the type of >equipment installed and the location.

>Most DCS and other communication systems are required to be connected to a >separate ground system with a separate ground well/electrode.

>Most lightning protection systems are now required to be installed with the discharge >ground electrodes physically separate to the building and equipment ground system >electrodes.

>This is based on the ideology of providing a path for the millions of volts presented by >a lightning strike to be shunted arround the building and/or equipment without >entering the equipment ground system and therefore exposing the >electrical/electronic equipment components to high voltage.

True...

__________________
--
Register to Reply
Guru

Join Date: Jun 2010
Location: srilanka
Posts: 2725
Good Answers: 5
#39
In reply to #26

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 8:03 AM

Please give the ref nr of the code where these are mentioned.

__________________
pnaban
Register to Reply
Power-User
Engineering Fields - Power Engineering - New Member

Join Date: Feb 2011
Location: Pakistan
Posts: 126
#40
In reply to #39

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 8:31 AM

pnaban writes:
>Please give the ref nr of the code where these are mentioned.
Ans: I just agree with him on that. I have mentioned it already in response # 35 earlier. Here it is again if it would help any? The overhead lines??;
[See clause 5.7.6 for requirements for protection against over- voltages.]
5.7.6 Where an Electrical Installation is supplied by underground cables, no special provisions are required for protection against over-voltages arising from atmospheric origin or from switching. Where an Electrical Installation is supplied by overhead lines, advice should be sought from the Distribution Company or the requirements of BS 7671 - Chapter 44 may be used.

__________________
--
Register to Reply
Guru

Join Date: Oct 2008
Posts: 42329
Good Answers: 1666
#41
In reply to #39

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 9:44 AM

Please try to keep up with the discussion. Already asked and answered!

Register to Reply
Guru

Join Date: Dec 2010
Posts: 1895
Good Answers: 44
#44
In reply to #39

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 2:27 PM

The diagrams like these which are in the NEC supplementals, and also found in Mike Holt's books and web site are great at depicting what the NEC mandates.

I don't have full access to mine right now since I am on vacation, sitting on a lanai using my ipad, but there is another pictorial diagram which depicts a common system with the required connections for the lightning arresting system.

The separate excepted ground rod is still required to be bonded to the building's system by the NEC and it is recommended by both the IEEE Green and Emerald books.

Due to the downstream bonding an extra measure of electrical system protection is provided from surges.

An excellent article near this subject is presented here: http://ecmweb.com/bonding-amp-grounding/grounding-vs-bonding-part-1-12.

Register to Reply
Guru

Join Date: Jun 2010
Location: srilanka
Posts: 2725
Good Answers: 5
#45
In reply to #44

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 9:53 PM

I believe "IEE On site guide " give this which is related to "IEE wiring regulations" or BS7671.

__________________
pnaban
Register to Reply
Guru

Join Date: Dec 2010
Posts: 1895
Good Answers: 44
#46
In reply to #45

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 11:18 PM

I don't know those guides or the British Standards.

However the old color series I referenced are now deprecated and bound into the 3000 series: http://standards.ieee.org/findstds/3000stds/index.html?WT.mc_id=tm_proj_3000

Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#47
In reply to #44

Re: Connecting Lightning System With Earthing/Grounding System

04/04/2014 3:22 AM

Good link, thanks.

I started reading it and came across some really good info at the bottom of page 2. The link is:-

http://ecmweb.com/bonding-amp-grounding/grounding-vs-bonding-part-2-12

I find this strongly indicative of the sort of problems that happen regarding other equipment when both earths are bonded as some say they should be.....not me though!!

When lightning occurs, high voltages drive high current (as much as 40,000A) into the earth for a fraction of a second. Typically, lightning strikes to wiring occur outside. Therefore, grounding (earthing) the system windings will assist the flow of lightning into the earth.

When a ground fault over 600V occurs, voltage on the other phases can rise significantly during the fault (typically three to 12 cycles). This voltage surge during the utility ground fault will be transformed into an elevated surge voltage on the secondary, possibly destroying electrical and electronic equipment. The lower the resistance of the utility grounding (earthing) system, the lower the secondary voltage surge.

Reading on demonstrates that the person who wrote it really understood code and also lightning strikes and their effects. A good practical person....sadly not all diagrams or pages are available to the casual reader....

Bur with currents up to 40,000 amps, it does not take a genius to see the voltage gradient over several meters of conductor, could allow really high voltages on any related equipment bonded earth-wise to that. Which is why I personally do not like to bond both grounds anywhere, ever. Though I have to admit, I never really thought much about it, except to keep them apart.....I am not a genius, just safe!!

In fact, in the past I have tried to keep them as far apart as possible.....that would appear to be code here as well, though I have not found the relative paragraph and I know only one engineer that is up to date (and on holiday!).....

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru

Join Date: Dec 2010
Posts: 1895
Good Answers: 44
#48
In reply to #47

Re: Connecting Lightning System With Earthing/Grounding System

04/04/2014 3:43 AM

I don't know if it was referenced in the article but NFPA 780 puts a lot of the theory into rules form as well.

Register to Reply
Guru

Join Date: Oct 2008
Posts: 42329
Good Answers: 1666
#29
In reply to #21

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 7:59 PM

A solution of biblical proportions.

Register to Reply
Guru

Join Date: Dec 2010
Posts: 1895
Good Answers: 44
#33
In reply to #21

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 2:37 AM

Please provide a current reference from the NFPA 70.

Register to Reply
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 31859
Good Answers: 1751
#6

Re: Connecting Lightning System With Earthing/Grounding System

04/01/2014 5:09 PM

I believe they are usually connected ....everything is grounded except gas lines...if memory serves...

__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#8

Re: Connecting Lightning System With Earthing/Grounding System

04/01/2014 10:52 PM

The grounds should be bonded to prevent or minimise step voltages.

The engineers are correct. They should tell you where/how to bond.

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Guru

Join Date: Jun 2010
Location: srilanka
Posts: 2725
Good Answers: 5
#9

Re: Connecting Lightning System With Earthing/Grounding System

04/01/2014 11:35 PM

Earths of all systems(Power,TV,lightning,Telecom,Computer,Fire etc etc)in any building should be connected together but I can remember that Lightning earth should be connected to other earth via a (TEC) transient earth coupling which is similar to a surge protector.

__________________
pnaban
Register to Reply
Member

Join Date: Mar 2014
Posts: 5
Good Answers: 1
#10

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 12:29 AM

First I must decide whether the term "lightning system," might actually mean the powered lighting system.

Any electrical power system must have a grounding system. This means that any metal objects that have power from the building system must have a ground connection that provides protection from accidental connections with hot conductors. Lightning protection systems won't function as intended to control lightning strikes if they are not grounded.

Aircraft are built with lightning dispersal accessories which distribute lightning strike energies back to the atmosphere.

Since there is a lack of agreement on how lightning strikes work there will be disagreement on how to best build a grounded lightning protection system.

In any case, electrical lighting grounding systems or lightning strike protection systems must be effectively grounded to earth.

My question. Why, on all the roofs with grounded lightning protection in place, have I never seen a grounded lightning rod tip melted from the plasma temperature that lightning bolts generate?

Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#17
In reply to #10

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 5:55 AM

Here, the house metal, except for gas pipes, are all centrally grounded physically together, then to ground itself.

Lightning conductors are not attached to this, they are grounded individually. My house has a ground connection at the front and a second one at the back for lightning only....they are I believe interconnected at the top of the roof.....I have not read code for Germany though....

My thoughts are that two connections are one better than one.....

I wouldn't like it if the L. strike got into the house earthing system, I bet I would be looking at a lot of damaged electronic stuff!!!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#18
In reply to #17

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 6:21 AM

If they're not bonded then, yes, you may well experience more electronic equipment damage than if they are bonded.

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Guru

Join Date: Jun 2010
Location: srilanka
Posts: 2725
Good Answers: 5
#22
In reply to #18

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 10:45 AM

For the room containing electronics they usually have separate Faraday cage and locate the room away from down conductors.

__________________
pnaban
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#24
In reply to #18

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 11:12 AM

I certainly doubt that (if I understood your misleading comment correctly!) !

Where is the damage/current path when they are separately grounded to any electronics?

Oh, I forgot to mention, being built at the high point of the village, we have been struck at least 10 times over the last almost 30 years..... No electronics were ever damaged during an electric storm....

The house across the road as well, also no damage.....

But, I read of lightning strikes where every single bit of electronics is turned into junk, but my insurance covers all that, just in case, with a new for old policy....never called on it.

But, a few years ago, some idiot turned off the mains for our whole village, and back on again within a couple of seconds and took out my laptop power supply (vaporised a PCB land that I replaced with a wire) and an external USB 2.0 backup disk drive interface....the drive itself worked fine and is still in use.....and that was just turning off and on the mains, probably with a big spike, but nothing else was damaged in the house.....the interface power supply is also still working as it should.....

Thats basically why I am REALLY sceptical about earthing the mains and the lighning conductors together.

Has anyone else here had experience of lightning strikes and how was your mains earth connected? Please join in.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#13

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 4:17 AM

You now have our opinions...

Ask the engineers to specify the standard(s), including specific clauses from which they are drawing their recommendations. You may then be able to confidently decide whose recommendation to follow.

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Guru

Join Date: Oct 2012
Location: 100 miles North from the World Center
Posts: 856
Good Answers: 42
#23

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 10:51 AM

I agree with redfred [and Andy Germany, of course!].

In my opinion the lightning protection has to be connected to the grounding [grid].

Both, NFPA 780/2004[See ch. 4.14 Common Grounding.] and BS 6651/1999 [See: ch. 17.3 Common network for all services] recommend a "common grounding".

__________________
Julius
Register to Reply Score 1 for Good Answer
Guru
Popular Science - Cosmology - Let's keep knowledge expanding Engineering Fields - Retired Engineers / Mentors -

Join Date: Dec 2006
Location: North America, Earth
Posts: 4402
Good Answers: 104
#27

Re: Connecting Lightning System With Earthing/Grounding System

04/02/2014 1:28 PM

The variety of answers was due to your unclear questions. If you had said "should lightning ground and power line ground be connected?" it would have been clear. Is that what you meant? If not, what? Did you mean lighting ground?

__________________
“I would rather have questions that can't be answered than answers that can't be questioned.” - Richard Feynman
Register to Reply
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6
#31

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 2:26 AM

7anoter4 is correct. NFPA requires them to be bonded together in the USA unless someone can quote anything to the contrary. this prevents difference of ground potential between the two systems. a large lightning strike will raise the ground potential, and there is alot of literature about this.

__________________
BSEE but always learning
Register to Reply
Guru
Popular Science - Cosmology - Let's keep knowledge expanding Engineering Fields - Retired Engineers / Mentors -

Join Date: Dec 2006
Location: North America, Earth
Posts: 4402
Good Answers: 104
#42

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 11:57 AM

As usual the OP is staring off into space, letting all of us guess about what he wanted.

__________________
“I would rather have questions that can't be answered than answers that can't be questioned.” - Richard Feynman
Register to Reply
Guru
Safety - Hazmat - New Member Engineering Fields - Retired Engineers / Mentors - New Member Engineering Fields - Piping Design Engineering - New Member Hobbies - DIY Welding - New Member Fans of Old Computers - PDP 11 - New Member

Join Date: Feb 2007
Location: Stronger Than The Storm
Posts: 2391
Good Answers: 202
#43

Re: Connecting Lightning System With Earthing/Grounding System

04/03/2014 2:20 PM

There was a similar thread earlier this year:

Lightning Protection

http://cr4.globalspec.com/thread/87627#comment988634

Good Luck, Old Salt

__________________
Any day on the green side of the grass is a GREAT DAY!, --- me +++++++++. I believe creativity is an inherent part of everyone. --- Kermit T. Frog
Register to Reply
2
Commentator

Join Date: Jan 2014
Location: Korba, Chattisgarh, India 495450
Posts: 64
Good Answers: 2
#49

Re: Connecting Lightning System With Earthing/Grounding System

04/05/2014 1:59 AM

I have missed this thread for discussions.

Now that I have seen the thread and comments, It may like to inform to all to note that in INDIA standards IS 3043 and IS 5309 meant for earthings allow both lightning earth grid and power earth grids (and for that matter all types of earthing grids) to be interconnected below the ground (minimum at two places if connected) - with a condition that in that case all the pits and system components MUST follow the stringent of the standards governing the specific to each of them. Like if power grid is separate the condition is grid must have a resistance of one ohm or less but lightning grid can have resistance up to 10 ohms. But when interconnected the common grid MUST have a resistance less than or equal to one ohm. And so gets governed the individual pit resistance without the grid. This is for info to all participantts in the discussion.

This goes by philosophy that Lightning is best diverted but this is not always possible so attract and ground.

Therefore wherever the clear separation of two grids is not possible this facility can be made use of.

__________________
Let us discuss the practical issues not the classroom.
Register to Reply Good Answer (Score 2)
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#50
In reply to #49

Re: Connecting Lightning System With Earthing/Grounding System

04/05/2014 2:22 AM

That's the way.

Common grid all strapped together below ground...

Only caveat is that the LPS downconductors, frame grounds, safety grounds, etc have to include removable links to permit testing of individual elements.

__________________
Difficulty is not an obstacle it is merely an attribute.
Register to Reply Score 1 for Good Answer
Register to Reply 50 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

1capybara (1); 7anoter4 (1); abasins (8); Andy Germany (5); Crabtree (1); cuba_pete (5); IdeaSmith (1); lyn (4); M.R.Iyengar (1); North of 60 (1); old salt (1); pnaban (4); redfred (1); SHOCKHISCAN (1); SolarEagle (1); StandardsGuy (2); TonyS (1); Too Cool (1); Tornado (1); Wal (9)

Previous in Forum: Generator Reactance   Next in Forum: Earthing Truck

Advertisement