Should I bond electrodes at metal poles that are 45 meters appart?

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Edtitus

New member
Location
Miami, FL
Hello,
I have a 3 km fiber optic ring for a network for CCTV cameras. In this fiber optic ring I have 10 "nodes". Each node has a POE switch that uses UTP cable to connect to 5 cameras in a star configuration. For example camera 1 is 90 meters to the left of the node, camera 2 is 45 meters to left, camera 3 is right on the node, camera 4 is 45 meters to the right of the node and camera 5 is 90 meters to the right of the node. All cameras are mounted on metal poles.
At first my design consisted on placing one electrode on each pole and use a standard POE surge protector on the camera side grounded to the electrode on the pole, and one POE surge protector on the node side grounded to the electrode on the node's pole.
So basically I have 5 poles on each node, about 45 meters apart, each with its independent electrode, and all that connects between the poles is UTP cable with a max of 24VDC 0.5A load from each camera.

In total we have:
50 poles with its independent electrode
10 nodes, 4 are powered from the same connection to one meter, 3 are connected to another and 3 are connected to another
50 IP POE cameras.

Our client consulted some "expert" and he convinced my client that all electrodes must be bonded together. After bonding the electrodes in a Ring (same path as the fiber optic cable) after a storm we got 16 burned cameras,3 burned nodes, 3 burned UPS units.

I opposed the bonding of all electrodes in the first place, as I think that 45 meters between each of them is more than enough, so bonging is not necessary.

I have been looking around on the internet and NEC to see if I can find something that supports my theory, but so far I have found nothing that supports either bonding them all together or leaving them independent of each other.

So I kindly ask for some advice on this matter. We have a technical dilemma because before bonding all electrodes together, nothing got toasted in almost 2 years and we had had many storms.

Thanks a lot
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
So I kindly ask for some advice on this matter.

I doubt that bonding or not bonding the plates together made any real difference.

If the guy that made the suggestion is an expert, and his advice failed to protect against a hazard he claimed that it would protect against, then your client may well have a legal case to make, especially if it can be shown that following the "expert's" advice actually increased the hazard.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Keep in mind that the scope of the NEC doesn't cover the protection of equipment from lightning damage. There's another NPFA publication for that. NFPA 780.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Keep in mind that the scope of the NEC doesn't cover the protection of equipment from lightning damage. There's another NPFA publication for that. NFPA 780.

NFPA780 only covers the installation of LPS. I am not sure it even covers LPS for equipment protection, but only for the structure itself.
 

luckylerado

Senior Member
If you applied 780, what you have is a counterpoise. For this to be effective you need the counterpoise conductor to be installed sufficiently above the cable being protected as to create a zone of protection and be bonded every 500? feet.. If laid in the same open trench or pulled in the same raceway this will probably cause more trouble than it will prevent.

I am assuming metal poles with no guy wires:
If you want to be compliant with 780 you will only need to bond the pole to an electrode. 8'x1/2" ground rod driven to 10' to the bottom is all that is required. The surge suppressors on both ends will be your best defense in my opinion assuming they are installed properly.

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