1,8 meters distance between grounding grids (telecommunications)

[Aticus]

Hi everyone,

I'm working in the earthing & bonding system of a rail system, within of it we have some technical rooms (HV, LV, HVAC, and COMs).
As is usual, the communications rooms has been designed with it's owns grounding grid, with no specific distance between the COMs grid and the general grounding grid. A few days ago we received a comment asking us to keep a minimum distance of 1,8 meter between the coms grid and the general grounding grid.
We were looking for the standar in which this point is show as mandatory, with no results (at least we couldn't find anything in EN 50310:2000 nor in NFPA70)
Could anyone say me the standard in which this statement is showed?

Thanks a lot.

 

[zbang]

I don't think you will find one as in many cases all of the grounding systems must be interconnected. If the traction power is using the running rails as a return conductor, it's already effectively earthed via the roadbed.

Motorola's R56, a well-respected standard for communications sites, says-

4.3 COMMON GROUNDING (EARTHING )
At a communications site, there shall be only one grounding (earthing) electrode system. For example,
the AC power system ground, communications tower ground, lightning protection system ground,
telephone system ground, exposed structural building steel, underground metallic piping that enters the
facility, and any other existing grounding electrode system shall be bonded together to form a single
grounding electrode system (ANSI T1.313-2003; ANSI T1.333-2001; ANSI T1.334-2002; IEC 61024
1-2, section 2.4.4; IEEE STD 1100-1999; NFPA 70-2005, Articles 250.58, 250.104, 250.106, 800.100,
810.21, and 820.100; and NFPA 780-2004, Section 4.14)

(You can readily find R56 online.)

I'm sure there's a IEEE standard for grounding/earthing power distribution.

 

[Aticus]

Thanks for your kind answer, we'll have it into consideration for sure.
Related to that:

I'm sure there's a IEEE standard for grounding/earthing power distribution.

I know this one: IEEE Std 80:2013 Guide for Safety in AC Substation Grounding.
Kind regards