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Hahausuck
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2 recommendations

[Tech Ops] Motorola R56 Document

Alright everyone. Motorola has made available for everyone to download, the bible on site grounding and construction. Feel free to download. In the past this was not to be distributed but they have since changed that.

(link removed at request of Motorola)

Enjoy!
--
"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it."



davidg
Good Bye My Friend
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good, it was a PITA to email out!


Hahausuck
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Tell me about it


lutful
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reply to Hahausuck

said by Hahausuck:

bible on site grounding and construction
Do you know when it was last updated? *** downloaded and reading ... updated in 2005 !

Recently I found a very comprehensive list of standards at »www.lightningsafety.com/nlsi_lhm···ety.html

*** 5. Codes and Standards

In the U.S. there is no single lightning safety code or standard providing comprehensive assistance. NFPA-780 is a general installation guideline for lightning protection systems. U.S. government lightning protection documents should be consulted.

The Federal Aviation Administration's FAA-STD-019d and the U.S Air Force's AFI 32-1065 are valuable. The IEEE 142 and IEEE 1100 Recommended Practices are suggested. Other recommended federal codes include military documents MIL HDBK 419A, Army PAM 385-64, NAVSEA OP 5, AFI 32-1065, NASA STD E0012E, MIL STD 188-124B, MIL STD 1542B, MIL STD 5087B, and UFC 3-570-01.

The International Electrotechnical Commission’s IEC 62305 series for lightning protection is a comprehensive reference document for the lightning protection engineer. Adopted by many countries, IEC 62305 is a science-based document applicable to many design situations.

***

NFPA-780 and IEC 62305 are paid only, but many of the defence docs are free. Let's find their links and/or archive copies somewhere safe. I recall the highlighted ones are already posted in previous threads.

Hahausuck
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reply to Hahausuck

As of fall last year they are working on an update.

they review several times a year though, and much of the information contained within is not only based of standards and science, but actual field experiences.


lutful
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Click for full size
I noticed that some suggestions contained in R56 (see above) was ridiculed in past discussions.

The grounding/bonding/SPD suggestions are actually extracted from existing standards - there is nothing surprising or new here. They do not address any "science" other than a few casual mentions of inductance and a very misleading statement on keeping everything equal potential.

IMHO the writers should gain some "field experience" on lightning surge protection because they cop out at every turn and defer to other standards.

*** R56 wording almost implies that critical equipment inside R56-compliant shelter could get damaged by lightning

3.9.1 " ... the most effective way of protecting the CO switch from lightning damage is to locate it separately from a communications site and accompanying tower at the same facility. Not only is the CO switch much more expensive to replace than typical communications equipment, but the entire system will fail if the CO switch fails. ... due to a lightning strike to the radio tower."

*** R56 does mention building structure is better than ground conductors, but in a vague manner with no specific guidance.

4.8 " In new construction, provisions shall be engineered into the building design for effective roof-mounted antenna mast and support structure grounding ... using effectively grounded structural building steel (preferred) ... metallic antenna support structures that are directly and effectively bonded to effectively grounded structural building steel. "

*** R56 cops out with "minimum" suggestions and defers to other standards.

4.9 "... all exposed buildings with rooftop towers shall be equipped with a lightning protection system, as outlined in NFPA 780-2004 ... engineering firm specializing in the design and installation of lightning protection systems should be consulted for proper design and installation of the building lightning protection system ... lightning protection system shall meet the requirements of BS 6651:1999, IEC 61024-1-2, NFPA 780-2004 ..."


davidg
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in MY experience complying with R56 makes a HUGE difference in the ability to safely divert the strike energy. some of the stuff may sound redundant or sound like it was taken from other standards without research, but i can tell you that it is there because as of the date it was written it is the best method around. i personally know several field TECHS that contribute to R56 revisions, not some engineer who sits behind a desk and tries to justify there job. when they find something works or does not work, they pass the info along and the manual gets updated accordingly.

if it is good enough to protect multi million dollar cell and public safety sites, it is more than good enough to protect another type wireless site that costs a fraction of that. is it costly to implement, sure it is. but preventing just 1 strike can often pay for the cost of implementation. i've seen a Rohn 80 tower glow orange for 2 minutes after a hard direct strike and have zero damage to any equipment installed to R56 standards. i was actually IN the equipment shack when the strike happened, the only way i knew it was the guy outside came in to see if i was ok and he said come look at the tower.

whether you choose to follow R56 standards is up to you. heck i know a guy that intentional cut loose every ground inside his building, including the grounds for electrical outlets/conduits, the only ground was the tower iteself, and he never took a strike again. was it luck, or was he on to something, i don't know and i ain't risking MY stuff to find out!
--
Lack of Preparation on YOUR Part does NOT Constitute an Emergency on Mine!


Hahausuck
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reply to lutful

The book was written to provide guidance. I have found some things are elaborated on somewhat while others are just stated as "do this, and if you want more information, look to X standard".

I don't see much of an issue with the method in which they are conveying the concepts and how-to's.

After all, the document is written for technicians to reference. Not everyone has a PhD in this stuff, and as such you have to make it simple enough for joe shmoe to follow.
--
"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it."


lutful
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reply to davidg

said by davidg:

if it is good enough to protect multi million dollar cell and public safety sites ...

R56 writers frequently mention meeting only the "minimum" requirements for grounding/bonding and mention many ideas for better performance are available in other standards.

said by davidg:

it is more than good enough to protect another type wireless site
They have actually asked their target audience to hire an engineering firm specializing in lightning protection systems for critical wireless installations.

Motorola provides very specific guidance for lightning surge protection of Canopy radio installations with simple diagrams for installers. »Best practice generalized from Motorola/Alvarion docs

FYI many aspects of outdoor WISP equipment protection are not covered properly in the R56 document because it was written for a somewhat different audience and purpose.

lutful
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reply to Hahausuck

said by Hahausuck:

you have to make it simple enough for joe shmoe to follow.
The problem is that Joe Shmoe does not often understand when and why he is expected to follow what guidance but wants to dispute engineers who do.

Compare R56's 911 shelter proteciton scenario with the recent debates in »Lightning damage pics

( EE: Electrical Engineer / XE: Experienced Electrician / XI: Experienced installer )

EE: pass all telecom-related cables (RF, T1, DSL, phones lines) into an outdoor shelter through a single bulkhead which is bonded using multiple wide straps to combined tower+shelter grounding system.
...
each must have surge protectors properly tested and UL-rated for lightning strikes ... AC coming into the shelter needs to have robust surge rotection on neutral as per IEC diagram.
...
I would not have cared as much if their solution only fried equipment but dangerous advice from forum electricians could actually kill [people] if they happen to be inside this shelter ... and lightning strikes nearby

XE: To mix Telco/coax togeather not [only] violates the ground window concept it is a unallowed practice.

XE: Each service SHALL have its own entry point and its own grounding bar which will be tied back to the proper grounding window of the sites MGB

EE: while it is often necessary to make compromises by using multiple entry (bonded together) for convenience, the single plate method does not become "absolutely incorrect"

XE: No single plates allowed* pure and simple maybe somewhere else in the world but not around here.

XI: it is prohibited by the guidelines we follow set forth by people who provide us with site installation guidelines.

EE: Some of [XE] suggestions could even prove fatal to someone in the shelter during a nearby storm

XI: Please enlighten me on this, comment. I have yet to see anything suggested by the member that could prove fatal. So far I see that it mirrors everything in my guidelines ...

That is just one aspect from that thread ... ground path's inductance, limitations of equipotential bonding, SPD types suitable for LPS, ... almost everything explained by EE was disputed by XE/XIs who are supposedly following R56.

We all have access to R56 now and can deduce when to seek other guidance for lightning surge protection.

Hahausuck
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That diagram is a bit different than the standard comm shelter.

By the time one has reached the point of that diagram it is assumed that the communications gear has been installed in accordance with the prior recommendations. That diagram is further up the food chain, so to speak. We do not single plate anything (maybe I am misunderstanding your definition/description of single plate?).

There ARE exceptions made however, such as at comm sites where there are POE radios, RF cables, CCTV POE, CCTV 24VAC, IF+Power, etc where they must all run in though the main entry window, but then they are all bonded at the EGB and MGB respectively (in the best manner possible). Even in these instances I will often use secondary SPD's to protect between equipment, most notably for example between the output of a DSx microwave system, and a MUX which is connected to other equipment.

EDIT TO ADD:

Telco and Optical always has its own entry point. This is how the shelters are built by the mfg's. In these cases we install a SSGB and bond it back to the MGB.

I won't argue any of the information in that drawing or the section of the guidelines from where it came.
--
"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it."


lutful
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said by Hahausuck:

That diagram is a bit different than the standard comm shelter ... That diagram is further up the food chain, so to speak ...We do not single plate anything ... Telco and Optical always has its own entry point.
Let us ignore "optical" for this extremely important argument about grounding/bonding of "metallic" conductors entering outdoor shelter. Let me rephrase the fundamental "science" which is being disputed in WISP fourm by a few electricians and installers by invoking various code and guidelines.

Maximum possible protection for both humans and equipment is provided by bonding every single metallic conductor (signal or power) within the smallest possible distance. A bonding distance of a few feet, even with perfect zero ohm conductors and perfect exothermic bonds, could produce killer voltage difference and damaging surge indoors.

Even if it has not happened so far, it will happen at some point in the future during a sufficiently strong lightning strike. The danger can also be demonstrated to skeptics by injecting simulated lightning surge of gradually increasing magnitude into such an installation.


Hahausuck
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I won't argue the point you made. I agree with the fact that bonding shall be done with the smallest distance possible.

The fact remains that we still are not to run all cables (telco, rf, power, etc) through the same entry.


lutful
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said by Hahausuck:

The fact remains that we still are not to run all cables (telco, rf, power, etc) through the same entry.
Because of what rule? What if you are building a emergency dispatch center and follow R56?


davidg
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said by lutful:

said by Hahausuck:

The fact remains that we still are not to run all cables (telco, rf, power, etc) through the same entry.
Because of what rule? What if you are building a emergency dispatch center and follow R56?
then you do NOT bring them thru the same entry nor run them close together.
--
Lack of Preparation on YOUR Part does NOT Constitute an Emergency on Mine!

Hahausuck
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said by davidg:

said by lutful:

said by Hahausuck:

The fact remains that we still are not to run all cables (telco, rf, power, etc) through the same entry.
Because of what rule? What if you are building a emergency dispatch center and follow R56?
then you do NOT bring them thru the same entry nor run them close together.
David is correct.

I wish I could show photos on the forum here or even in private but I cannot....

Each service type enters from different locations, but most ideally on the same wall as the RF feeders.
--
"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it."

lutful
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Click for full size
said by Hahausuck:

I wish I could show photos on the forum here or even in private but I cannot....
Let's discuss using diagrams/photos within R56 and other guidelines. See above from R56 for follwing question. If necessary we can draw on them clarify.

said by Hahausuck:

Each service type enters from different locations, but most ideally on the same wall as the RF feeders.
I am curious what rules prohibit different type of comms cables (coax, POTS, DSL, T1, control, etc) entering through a single "integrated" bulkhead plate like this?

If there are rules about minimum separation distance, what exactly is it? Because if shelter wall is made of metal, multiple entry plates are acting just like a single plate. Or do you have to intentionally put insulating backing behind those separate plates to satisfy some clueless "code" inspector?

Hahausuck
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Those entrances are specific for RF cable entries, and the book although not directly stating, insinuates as such.


Hahausuck
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reply to Hahausuck

I do not recall seeing any defined 'rules', but the book is a guideline (written by EE's, Electricians, Technicians, and others) so I am sure they have their reasons, even though they do not point to anything specific.


lutful
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reply to Hahausuck

said by Hahausuck:

Those entrances are specific for RF cable entries, and the book although not directly stating, insinuates as such.
Most probably you meant "coaxial" cable ... not realizing that they can be made to carry all "services" mentioned earlier plus AC/DC power too. However that is not my argument. Such "Integrated Cable Entry" systems are designed to bring in every single connection safely - including AC power - into a shelter.

Read the paragraph preciding that diagram carefully and you can "insinuate" that it won't violate NEC to make the inner surface MGB for the shelter.

Hahausuck
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What I meant was those entries are used for exactly what I stated.

I've never seen them used for anything otherwise though one could do such if they wanted to.

And yes one could insulate it from the wall should one be required to.


lutful
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said by Hahausuck:

What I meant was those entries are used for exactly what I stated ... I've never seen them used for anything otherwise though one could do such if they wanted to.

If you are given clear and written directions by an engineering firm to use the same integrated bulkhead panel to bring in AC power, RF coax, POTS, telco, misc control, and even fibers with metallic strength members, ... please do not change the design based on what you think is correct or allowed.

said by Hahausuck:

And yes one could insulate it from the wall should one be required to.
EEs will never provide such a criminally dangerous suggestion, so you are very unlikely to face such a requirement.

Hahausuck
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said by lutful:

said by Hahausuck:

What I meant was those entries are used for exactly what I stated ... I've never seen them used for anything otherwise though one could do such if they wanted to.

If you are given clear and written directions by an engineering firm to use the same integrated bulkhead panel to bring in AC power, RF coax, POTS, telco, misc control, and even fibers with metallic strength members, ... please do not change the design based on what you think is correct or allowed.

Why would someone do that? Example: If we are given directions to do something we follow them to the T. Hence, we follow R56 to a T as all of our designs are based on R56. When we plan our own sites we build the site following R56 word for word, no more no less.

Are you assuming I or anyone else would blatantly disregard the directions of the system designers?
--
"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it."

Hahausuck
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reply to lutful

said by lutful:

said by Hahausuck:

And yes one could insulate it from the wall should one be required to.
EEs will never provide such a criminally dangerous suggestion, so you are very unlikely to face such a requirement.
I've seen it done before. On both Civil and Electrical.....
--
"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it."

lutful
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2 edits
reply to Hahausuck

Click for full size
said by Hahausuck:

If we are given directions to do something we follow them to the T. Hence, we follow R56 to a T as all of our designs are based on R56. When we plan our own sites we build the site following R56 word for word, no more no less.
What do you do when R56 provides multiple alternatives? Can we choose clamping instead of exothermic bonds? Can we choose bonding/grounding path through building structure instead of copper conductor?

But I really wanted to ask some more relevant and important follow-up questions. Please consider above telecom shelter diagram from R56.

Assume operator wants to bring in some copper T1 and POTS lines into same shelter from different service providers for redundancy.

Assume you have decided to use separate entry panel "per service" because you think it is prohibited to run them through unused conduits in that panel.

What is the R56 guidance on minimum physical separation between separate entry panels?

Do you use one [panel/conduit] per T1? One per service provider if they supply both T1+POTS lines? One for all T1 lines together even if they come from different providers? I reduced some text clutter and drew in 2 panels but you can suggest any number of panels/conduits located anywhere around the shelter.

Where/how do you bond these separate service entry panels/conduits and related surge protectors to the external/internal grounding system?

And one more question, should they have put some more distance between AC and coax entry panel? For a bit more "protection" from lightning surge perhaps.

Hahausuck
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1 recommendation

When there are multiple alternatives one should follow the document for those types of situations. When there are questions, one should consult Motorola (if following R56) or contact the appropriate EE firm specializing in grounding and earthing.

Telco typically enters in through the designated telco entry area, be it near the RF feeder entrance or elsewhere in the shelter. This is how all shelters are built from what I have found in the USA. The only thing entering the shelter through the RF cable entry port is RF cables (antenna lines, CCTV, POE, IF+power, etc). That is it, nothing more. I don't know why that is such a hard concept for you to grasp but it is just done that way. I am sure the documents that everyone follows (be it R56, RO Associates, Bell, etc) have it stated as such. It just is how it is done and no one is about to change, so even though you may not accept it (your choice) myself and the rest of the industry is not about to change unless we are told so by the manufacturers or industry standards change.

Sheath bonding (both CU and Optical cables) and SPD's shall be bonded using an appropriately installed SSGB and bonded back to the MGB which is then in turn naturally bonded to the EGB and site ground system. If there are multiple entries then those should be treated the same as far as grounding and bonding. Everything bonds to the MGB. Please read the section on the MGB for further information.

As far as spacing of electrical, I do not find anything dictating X distance but this is stated throughout the manual:

To facilitate single-point grounding, request that electrical service enter the site building on the same wall as and near to the entry point for the antenna transmission lines.

I cannot answer any more questions, i suggest reading the entire document, that should clarify all of your questions. Further questions should be directed to Motorola Engineering. I am sure if you had some valid reasons to not do something they would be interested in listening to them provided they meshed with the standard communications site installation practices and other industry standards and rules and laws.

--
"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it."


lutful
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said by Hahausuck:

be it near the RF feeder entrance or elsewhere in the shelter ...
There must be some guidance electricians follow on maximum distance? Because the physical distance between conductor entry points, even if bonded with zero ohm path, determine the real danger to both humans and equipment during a lightning surge.

That is why R56 document contains clear guidance such as "AC Power, Telephone Circuits, Cable TV, CCTV, and card access control cables must enter within the same area" for absolutely critical installations like dispatch center in the first diagram I copied. That is also why the AC entry is so close to the integrated bulkhead entry in the second diagram.

Even 3ft separation between well-bonded/well-grounded/well-protected entry points may kill someone and damage lots of equipment with a sufficiently strong surge. The relevant electrical engineering calculations are simple and "as built" installations can be tested with simulated lightning surge.

No need to wait for detailed engineering analysis after an unfortunate event like Sago coal mine in Virgina.

Hahausuck
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I assume so on the distance.

I just don't have any concrete answers on this part, other than what the books say to do/not do coupled with the fact that all of the shelters I have been at either have it on the same wall as the entrance, OR the power enters from a spot across the room on a completely different wall.

This experience holds true for cellular site installations, and I am pretty sure they have qualified engineers design those systems.
--
"No job is so important, and no service is so urgent that we cannot take the time to perform our work safely."
-- AT&T, Your World, Destroyed.
--Safety One Tower Rescue Certified
--LLigetfa:"Wimax is like teenage sex. Everyone talks about doing it."


lutful
... of ideas
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join:2005-06-16
Ottawa, ON
kudos:1

4 edits

said by Hahausuck:

OR the power enters from a spot across the room on a completely different wall
So far I found these general guidelines about service entry:

" preferred configuration for a stand-alone equipment shelter is to have all utilities enter the structure through a common wall as close as practical to the transmission line entry port location."

"Antenna transmission lines and other communications cables with metallic sheaths shall be grounded as close as practical to their point of entry into the building or shelter"

"RF transmission SPDs shall be bonded to the MGB within 610 mm (24 in.) of entry"

"RF transmission line SPDs may also be bonded directly to ... integrated entry panel"

"purpose of the external ground bus bar (EGB) is to provide a convenient grounding (earthing) termination point for antenna transmission lines (coaxial cables) and other cables prior to their entry into a building or shelter"

Logically combining such clear guidance, it seems to me that R56 will allow all telecom services to enter through a single "integrated cable entry" system.