lutfulPremium
join:2005-06-16
Ottawa, ON Reviews:
 ·TekSavvy DSL
2 edits | proper lightning surge protection of electrical panels *** edited to remove sarcasm *** A diagram from DEHN (with my comments) show recommendation by IEC global standards followed by most countries and even used by NEC/NFPA for code updates. 
said by public:said by lutful:FYI even a short grounding strap with 0.1 ohm resistance will develop 1000V potential difference when it is carrying 10,000A from an average strike. You still have to add the Ldi/dt term which makes the voltage rise much greater. Yes.
Sadly most of our forum experts "stick with what they know" which may not include even a basic understanding of Kirchoff ... I occasionally try to clarify that we can't keep "everything equipotential" during a lightning surge and that popular grounding/bonding suggestions in WISP forum could invite potentially fatal current into homes and fry outdoor gear. 
*** update: Please see new post below ... the one with diagram and comment from US MIL handbook 419 on grounding/bonding. |
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| Re: absolutely stupid example of grounding and bonding ... i don't know if you aware about that Dehn is one of the few that at least give you an concept of how stuff has to be made if it goes to surgeprotektion.
a littel bether example from them
»www.dehn.de/pdf/ds/DS614e.pdf
note the example is for a Installation like its comonly in europe ...
where not everything is bondet together to grond if it makes sence ore not judge yourself |
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lutfulPremium
join:2005-06-16
Ottawa, ON Reviews:
·TekSavvy DSL
2 edits | said by Airnode:i don't know if you aware about that Dehn The provocative title was a joke aimed at electricians who "stick with what they know" ... 
Dehn is absolutely the best company for lightning surge protection. Above example implementation of IEC recommendations could be used for home or WISP NOC.
This outdoor video camera example sends AC power from the indoor panel with surge protector on both sides with no additional bonding conductor. Similar setup can be used for many WISP AP/CPE sites if you change to appropriate PoE/RF surge protectors.
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 John GaltForward, MarchPremium
join:2004-09-30
Happy Camp
kudos:3 | said by lutful:said by Airnode:i don't know if you aware about that Dehn The provocative title was a joke aimed at electricians who "stick with what they know" ... Apparently you are incapable of understanding that electricians have no interest in whether or not equipment survives a lightning strike.
You might refer to Article 90.1(A) & 90.1(B)...
Communications Engineers do, however, and they do not rely on the vast majority of materials and/or methods used by electricians as very few of them are suited for the particular task at hand.
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Remember, Tuesday is Soylent Green Day.
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| reply to lutful
Electricians and communications people have two different "best practices", unfortunately those practices do not fully satisfy each other's goals.
Electricians strive for safety and protection of life and property. They often do not encompass practices necessary for data communications. I have repulled CAT5 cable where an electrician used a come-along to pull the cable through conduit. I've seen installs where an electrician used wire nuts on data cables.
Communications guys will happily pull CAT5 between buildings and not use correct inter-building bonding to ground. |
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| reply to lutful
said by lutful:A crazy diagram from DEHN (with my comments) show bizarre and stupid recommendation by IEC global standards followed by most countries and even used by NEC/NFPA for code updates Can you tell me specifically what part of the drawing is a stupid recommendation that is now part of the NEC update, and can you tell me where the update can be found in the NEC recommendation. |
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| reply to lutful
said by lutful:A crazy diagram from DEHN (with my comments) show bizarre and stupid recommendation said by lutful:Dehn is absolutely the best company for lightning surge protection. Above example implementation of IEC recommendations could be used for home or WISP NOC. |
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 Killa200Premium
join:2005-12-02
Southeast TN | reply to lutful
I think his "A crazy diagram from DEHN (with my comments) show bizarre and stupid recommendation" was just bay conveyance of sarcasm judging from him later saying:
"The provocative title was a joke aimed at electricians who "stick with what they know" ... " |
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| But still...I'm trying to understand his contradictory statements. |
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Killa200Premium
join:2005-12-02
Southeast TN | reply to lutful
No offense to lutful, but good luck on that nevtxjustin. I have a hell of a time understanding you sometimes lutful, i have no idea why. |
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lutfulPremium
join:2005-06-16
Ottawa, ON Reviews:
·TekSavvy DSL
| said by Killa200:No offense to lutful ... I have a hell of a time understanding you sometimes lutful, i have no idea why. Sorry ... I was trying to show how qualified professional electrical engineers actually satisfy code-related safety bonding requirements without sacrificing lightning and surge protection. The original diagram from DEHN actually shows a very smart implementation of IEC rules for any WISP facility ... please read my own comments about the key protection features.
Lightning surge protection of a main electrical panel will require 50-200kA (10/350us) devices correctly connected to the external grounding system. Using typical 5-20kA(8/20us) stuff (shown in Rhaas thread) and incorrect bonding of protector grounds to satisfy "code" or maintain "equipotential" would be grounds for criminal liability in most countries.
FYI I have been frustrated that a few electricians are offering truly dangerous bonding/grounding suggestions for outdoor WISP equipment and they resort to mocking on the rare occasions when someone tries to improve their understanding of the basic physics of lightning and surge protection.
I was trying to explain that it is impossible to maintain equipotential voltage during lightning surge between outdoor and indoor equipment. I had also tried to explain that it will be dangerous to directly bond the internal ground bars of 2 outdoor structures with a sketch that I had quickly made using Paint program. I often take a diagram from a relevant source and modify/annotate to illustrate a technical point - like this one from US MIL handbook 419 which highlights the same point. |
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| reply to nevtxjustin
said by nevtxjustin:said by lutful:A crazy diagram from DEHN (with my comments) show bizarre and stupid recommendation by IEC global standards followed by most countries and even used by NEC/NFPA for code updates Can you tell me specifically what part of the drawing is a stupid recommendation that is now part of the NEC update, and can you tell me where the update can be found in the NEC recommendation. Still waiting......... |
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lutfulPremium
join:2005-06-16
Ottawa, ON Reviews:
·TekSavvy DSL
2 edits | said by nevtxjustin:Can you tell me specifically what ... is now part of the NEC update IEC standards are indeed used by NEC/NFPA for code updates and you can "safely" add UL too.
*** correction of my above comments ***
I have a hard time accepting that some US electricans are updating NEC to remove any influence of IEC but fortunately NFPA claims they "are able to influence the development of ISO and IEC standards" ... and NFPA staffer Mark W. Earley is currently part of the IEC "Electrical Installations of Buildings" standard development committee.
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3 edits | said by nevtxjustin:Can you tell me specifically what ... is now part of the NEC update Can you Google for the word "specifically"?
I want to see NEC update paragraph citations that you based your claims on.
Side note, I only did ONE edit to this post. The Moderator did two edits to delete what was complained by someone that got their feelings hurt as I might have been "trolling". |
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 SplitpairPremium
join:2000-07-29
Cow Towne
kudos:3 | reply to lutful
Re: absolutely stupid example of grounding and bonding ... Don't know where you found that diagram but it is missing a few very important parts of lighting protection and is not representative of power distribution across most of the U.S.
First of all if it is to be taken literally it diagrams the lightning striking the static line which will pass the majority of the energy to the earth with the remaining power spreading out to the bonded to ground MGN.
Second it does not include primary transformer protection which would be fired over to earth and the MGN on a primary line strike and that in of itself due to follow through power and depending on the number of grounds per mile on the MGN can cause more damage than the actual hit.
Wayne
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If you cannot fix it with a buttset and some beanies you're not a technician. |
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| said by Splitpair:Don't know where you found that diagram but it is missing a few very important parts of lighting protection and is not representative of power distribution across most of the U.S. You mean Fig.3-12? Its lifted from Military Handbook MIL-HDBK-419A. Its also lacking that it does not show the ground wire that runs on top of the buried cable, all in the same trench.
Military facilities grounding is extremely effective. Unfortunately someone choose to cherry pick a drawing where the intent was show show a dangerous grounding practice, rather than a drawing that shows what is actually practiced. |
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