Grounding Comm. Poles In Mexico

[dwayapet]

I have a question which relates to grounding a communications pole outside in Mexico. The pole is about 15' tall and is a composite pole. I have wireless Antennas and AP's attached to the pole. I have found it to be the norm to always ground communications poles outside by means of a rod near the base of the pole and bond the respected boxes and devices to the ground rod by means of a #6 AWG.

I am being presented with the design of having the ground wire ran into the builidng through the same conduit feeding the pole. Now I am no rocket scientist, but I don't know if they understand the implecations of bringing in overvoltage such as lightning into the facility.

What can be their reasons for wanting to bring the ground into the building rather than installing a 5' rod near the pole and bond to it?

Any feedback and further check to my sanity is welcomed.

dwayapet

 

[electricmanscott]

Gorund rods at the pole will not provide a means to clear a fault in the event that one occurs and could result in a dangerous condition. The egc should be run back to the panel along with the circuit conductors.

 

[iwire]

I am being presented with the design of having the ground wire ran into the building through the same conduit feeding the pole.

If there are power conductors coming from the building to the pole it is required and necessary for safety that a grounding conductor be run with the power conductors all the way back to the source.

You may add as many grounding electrodes at the pole as you want but they must be in addition to the grounding conductor from the source.

What can be their reasons for wanting to bring the ground into the building rather than installing a 5' rod near the pole and bond to it?

Electrical safety.

 

[dwayapet]

There will be no 120vac installed to the pole. The only thing that will go to the pole is a copper CAT-6 UTP cable to supply POE to the AP.

 

[iwire]

2005 NEC 810.21 may apply.

 

[dwayapet]

So in my situation since the pole is about 100' away from the building, mounting it into the ground(soil), then installing a ground rod and bonding the ap and antenna is ok. I have no 120vac needs to the pole and will not be plugging any device into any outlet, all PoE. I am only running a CAT-6 shielded cable to the pole that will be bonded and protected at both ends and will provide my PoE.

I guess my concerns are if the antenna gets hit, that it's voltage stays outside and not go into the building.

Your thoughts?

 

[dwellselectric]

I was in Mexico last October and it was the first time that I have ever seen utility poles made out of cement instead of wood. Very interesting I am guessing due to the hurricains?

 

[brian john]

countries where I have lived it was a lack of wood. Here (USA) it could be a better utilization of resources?

 

[Rampage_Rick]

We have trees up the wazoo here but I've still seen plenty of concrete poles.

I've been on the other end of the stick too. We call the pole guys first when we fall timber, because they pay highest of anyone for prime toothpicks.

 

[haskindm]

So in my situation since the pole is about 100' away from the building, mounting it into the ground(soil), then installing a ground rod and bonding the ap and antenna is ok. I have no 120vac needs to the pole and will not be plugging any device into any outlet, all PoE. I am only running a CAT-6 shielded cable to the pole that will be bonded and protected at both ends and will provide my PoE.

I guess my concerns are if the antenna gets hit, that it's voltage stays outside and not go into the building.

Your thoughts?

Since you have "metallic connections" between the tower and the building due to the CAT-6 wiring; in the event of a lightning strike, current will flow into the building. What the designer is attempting to do is to keep the potential of the tower and the building the same so as to minimize this current flow. During a nearby lightning strike the potential of the two structure will be different due to the laws of "fall of potential". During this time (brief as it may be) there will be current flow over any conductive paths between the two structures - including the CAT-6. By providing an intentional low-impedance path, you are keeping the current flow over the CAT-6 to as small a value as is possible as the majority of the current will follow the lower impedance path of the grounding conductor.
Hope that makes sense.