Previous in Forum: Limiting Current to Trailer While Driving   Next in Forum: Neutral Current In 1 Phase Configuration
Close
Close
Close
5 comments
Rate Comments: Nested
Guru

Join Date: Feb 2008
Posts: 638
Good Answers: 45

STANDARD(S)? - Grounding and Bonding for Communication Site (Tower)

06/01/2010 4:05 PM

Ultimately, the end state is to have a communication site that employs equipment and antenna protection from both lighting and power ground faults.

I wish to deploy a transportable shelter (on wheels) that includes a telescoping (67 foot) tower. The question raised is "What minimal grounding can I implement in an effort to reduce site prep (trenching, drilling for ground rods, etc)?

The context of answering this question is around two standards; MIL-STD-188 "Grounding, Bonding and Shielding" and Motorola R56 (a standard that the shelter manufacturer is accustomed to following.

As an engineer with liability at stake for making a "minimum grounding" recommendation, I am somewhat hesitant to make a recommendation or support any quick install counterpoise and a few ground rods.

The nice thing about standards is that there are so many...

From others, suggestions range from a simple triad ground. Another suggestion is radials. Yet a third suggestion is a second down conductor. What?

So the MIL standard outlines requirements for earthen resistance, conductor size, minimum counterpoise locations, spacing of ground rods etc. However, such requirements define the MINIMUM CONFIGURATIONs.

Does it not all come down to "resistance to earth"? You can follow minimum configuration standards until the cows come home. Until you can meet the resistance to earth metric, you just don't have the earthen ground system needed to contend with lightning. NO?

As an engineer recommending the standard and methods for obtaining the earth resistance, I suspect that the soil conditions will make it extremely difficult to achieve the necessary earthen resistance. This leaves me with the dilemma of; No matter how I engineer it, it is likely to fall short of providing the protection needed.

What would you do?

__________________
This moment is as it should be.
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Power-User
United States - Member - American all the way Hobbies - Target Shooting - Aint nuthin like killing an innocent soup can!!!

Join Date: Jun 2010
Location: Brownsville, Oregon, USA
Posts: 345
Good Answers: 10
#1

Re: STANDARD(S)? - Grounding and Bonding for communication site (tower)

06/01/2010 4:15 PM

Lack of continuity or proximity of conductors to the earth would eliminate the risk of lightning strike. In other words, enough insulation would protect you as well.

__________________
Give me enough duct tape and I can fix anything!
Register to Reply
Guru
United States - Member - Member Engineering Fields - Electrical Engineering - Electrical Construction

Join Date: Apr 2010
Location: Mid Western USA - The Corn Belt
Posts: 1439
Good Answers: 58
#2

Re: STANDARD(S)? - Grounding and Bonding for Communication Site (Tower)

06/01/2010 5:23 PM

I don't know if this will answer your question directly but have you considered consulting with a lightning protection contractor?

I have used the firms below on a few occasions and have always had good results and no claims.

I don't know if you are in the US but a couple of the larger providers here that may be able to help you are Thompson Lightning Protection (you can get an e-mail address by Googling the name) Union Lightning Protection Installers (Google this one also)

Also Lyncole XIT Grounding out of Torrence CA is a manufacturer's rep I have used where we have had to do earth grounding in areas where bedrock was only 18" to 24" below grade (kind of hard to sink a 10' ground rod in that).

The engineers at these firms are very knowledgeable and are usually more than willing to offer a solution provided that you can supply them with detailed equipment and site sketches. E-mail is best. You can get an email address on their web sites after you Google and find them. You can request design, price and a BOM.

Each of the companies above are all licensed, bonded, insured, and UL approved sellers/installers.

A saying in my trade that I hear often is "when in doubt, sub it out". Sounds like this may be useful for you.

Good luck!

__________________
The first 5 days after a weekend are always the hardest................................
Register to Reply
Active Contributor

Join Date: Aug 2009
Location: USA
Posts: 19
#3

Re: STANDARD(S)? - Grounding and Bonding for Communication Site (Tower)

06/02/2010 12:33 PM

You might consult 29CFR1910.268.

Register to Reply
Member

Join Date: May 2010
Posts: 8
#4

Re: STANDARD(S)? - Grounding and Bonding for Communication Site (Tower)

08/15/2010 8:12 PM

MIL-STD-188 is Military Standards ,and there are 100 series ,200 series ,& 300 series...

Register to Reply Score 1 for Off Topic
Guru

Join Date: Feb 2008
Posts: 638
Good Answers: 45
#5
In reply to #4

Re: STANDARD(S)? - Grounding and Bonding for Communication Site (Tower)

08/18/2010 1:09 PM

What would you do?

__________________
This moment is as it should be.
Register to Reply
Register to Reply 5 comments
Copy to Clipboard

Users who posted comments:

farmatt (1); findstandard (1); KJK/USA (1); SM607 (1); szwasta (1)

Previous in Forum: Limiting Current to Trailer While Driving   Next in Forum: Neutral Current In 1 Phase Configuration

Advertisement