Grounding System for telecommunication Towers 1

[ruvini]

What is the recommended method for grounding of telecommunication towers?
When using cu plated rods for grounding what is the space between two rods?

 

[fsmyth]

Guyed towers or self-supporters?
On the towers I used to maintain, we set 10' rods at
each corner of the pad, 6' apart, below grade, connected
in a ring, with a bare #2 from each rod back to the
tower base. This was connected back to the building
gounding system, which had it's own similar ring, which
was then bonded to the service ground.
All the antenna feed lines terminated at a plate mounted
in the wall of the building, which was grounded with a
piece of #2 to the wire connecting the two grounding grids.
Sometimes the plates had bulkhead connectors, sometimes not.
Each feed line had its own braided strap connecting to
the plate, and the tower at both ends.
In extreme cases, where the tower was the only lightning
rod <g> for miles, a second ring was added 10' out, and
each corner rod bonded back to the inner corner, with
1" flat braid connecting the inside ring to the tower base.
The size of the wire is much less important than keeping
all the runs as direct as possible, and avoiding tight bends
That was just for the 300'-500' guyed towers.
On the 800'-1500' broadcast towers, the story was a bit
different, but I doubt you are asking about those.
100 footers just had a couple of 8' rods spaced two feet
out from the base. If the radio was in an exposed
weather-proof cab, it had it's own rod, unless it was
tower-mounted.

Self-supporters are pretty much self-grounding. The
corner pads had a single rod buried in the hole before
the pad was poured if we installed tower, but that was
probably unnecessary. The building protection was the
same in all cases.
The building service was run underground from the pole,
which had it's own one or two 8' rods, as was any telco
or other remote wiring (we always had the phone company
terminate at the pole, instead of the building).

A lot of this was overkill, but in 15 yrs of service,
we never lost a radio to lightning. Lots of exploded
antenna masts, until we quit using fiberglass, and switched
to using only exposed grounded elements, tho'. Never did
see much effect from the stringer balls we tried.

On other towers I worked on, the grounding was a
hodge-podge; they usually had a couple of rods for the
tower, and one for the building. Fixed a lot of receiver
front ends on those. Part of the service contract on
equipment on customer-owned towers included proper grounding.

<als>

 

[rob46]

Review Motorala "Standards and Guidelines for Communication Sites R56". R56 contains very clear information re: telecommunication tower grounding.