I am currently caught in between 2 difference schools of thoughts regarding if Lightning ground should be bonded to Building's bond, the scenarios are explained below and would like an explanation of basis why there are differing standards existing.
I have just been appointed to oversee Fiber Optics and Networking cables laying project at my workplace
All laying has now been completed and the Contractor is now seeking payment. However during the audit, we have differences in opinions as to whether the groundings should be bonded.
I am currently in Indonesia where Electrical Codes and Standards are just guidelines (not law) and rarely adhered to. Different "experts
" i spoke to have very different opinions. As the project leader, I need to be sure what the Contractor did was sound before payment is done. I would like to seek answers because even google give conflicting answers.
Indonesia national electrical code is last updated in 2000 and is based on NEC. here are the versions of interpretation I encountered.
(Contractor's Version based on IEC 1024)
says the Server room's grounding system (2.5 ohm) has to be bonded to Lightning protection's ground (3.5 ohm). Building electrical ground is currently bonded to Server's ground.
(Building inspector based in Singapore, and a British electrical engineer graduate based in Indonesia)
says that lightning protection's ground must be stand-alone from other grounding electrodes. Building and communications ground can be bonded together but not to Lightning's ground.
there can be a few and bonded lightning electrodes so long they are no where near non-lightning grounding electrode.
(my google research)
NEC 250.50, 250.60 and 250.106 seems to be in conflict with one another.
This is what i got from http://ecmweb.com/grounding/electric...vs_bonding_10/
"bond this system to the building (or structure) grounding electrode system [250.106]. Do not use the grounding electrode for a lightning protection system as the building (or structure) grounding electrode (250.60)."
"Earth-grounding electrodes Down conductors must be connected to earth-grounding electrodes that are dedicated to the lightning protection system. In other words, the grounding-electrode system for the service equipment for the facility, as well as that used for grounding telecommunications and cable television systems, must not be used in lieu of lightning protection electrode"
and from http://ecmweb.com/grounding/electric..._vs_bonding_6/
"If you use a grounding electrode for a lightning protection system, you can't use it as a grounding electrode for the structure grounding electrode (earthing) system required by 250.50. The purpose of a lightning protection system installed per NFPA 780 is to protect the structure from lightning damage. The concern that bonding the lightning protection system to the building grounding system may create a path for lightning into the electrical wiring or equipment within the structure doesn't justify keeping the two systems separate; separation creates a dangerous potential between them. You must bond your lightning protection electrode system to the structure grounding electrode (earthing) system (250.106)."