Grounding Bonding with Aerial Lashed Fiber

F

FloridaSplash

Member
Location
Central Fl
Occupation
Business Owner
OK all, new to the forum but have always been a MH fan! I run a business that builds Fiber Optic Networks. Most of our work is underground but we stumbled into an pre-existing situation yesterday at the request of a new client that had a recent lightning strike. Its at a ballfield where there are two buildings about 150' apart. One is a concrete structure and the other has a concrete base with a metal upper floor. There is a steel messenger cable installed that supports the fiber cable between the two buildings. One end anchored to the upper level building steel and the other anchored into the concrete building. Client claims they have video of the lightning striking the messenger cable and it wiping out the network switch the fiber was plugged into but the UPS was not affected. This is a stretch in my mind but i have seen some strange things with lightning over the years. The cable is all dielectric, so zero chance of that being related. I would assume the building steel on the one side of the attachment would be bonded. The client is demanding that we place ground rods at both ends of the aerial run and ground the messenger. I am pretty sure that's going to create more issues. Thoughts anyone?
 
OF course thats assuming there is already a legitimate ground, driving two disparate ground rods in addition to the existing could create potential between them. I get its a lightning control issue, if no one else sees this as potentially problematic, ill take that and run. Apparently this has been in place for 6-7 years.. certainly not the first lightning storm in FL
 
FloridaSplash said:
OF course thats assuming there is already a legitimate ground, driving two disparate ground rods in addition to the existing could create potential between them.
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All grounding electrodes including lightning protection must be bonded together for equipotential.
 
FloridaSplash said:
OF course thats assuming there is already a legitimate ground, driving two disparate ground rods in addition to the existing could create potential between them.
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How does grounding the messenger cable change anything other than connecting it to earth? As Roger stated if there are other electrodes they would get connected together.
 
jim dungar said:
This appears to be a lightning 'control' issue. It is not governed by the NEC.
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Overhead communications cables if they have a metallic path back to the utility pole and are attached to a building I think need to be bonded per NEC 800.100 no matter what type, POTS CATV Fiber optic whatever, if it has a metallic path that is bonded at the pole end it needs to be bonded to the grounding electrode system.
UG fiber probably has no metallic messenger.
Communications utilities here have long required their DMARC or as the NEC calls it "Primary Protector" to be within 18" of the electrical service.
 
tortuga said:
Overhead communications cables if they have a metallic path back to the utility pole and are attached to a building I think need to be bonded per NEC 800.100 no matter what type, POTS CATV Fiber optic whatever, if it has a metallic path that is bonded at the pole end it needs to be bonded to the grounding electrode system.
UG fiber probably has no metallic messenger.
Communications utilities here have long required their DMARC or as the NEC calls it "Primary Protector" to be within 18" of the electrical service.
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But.
The OP said the messenger cable ran between two buildings and the fiber was non metallic.
 
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