Not really possible to comment without seeing the installation. Noting that extraneous-conductive-parts only require bonding to conform to BS 7671 in buildings. In some circumstances, there may be safety and/or lightning protection implications ... and without further information, it's not possible to understand whether the communications engineer has considered those in their design.

Can you please explain the ref to "safety" in your response?

One safety implication would be the possibility of differing potentials between the bonded horizontals and unbonded (but Earthed) verticals -- anyone able to touch both simultaneously may be at risk of a shock, if the circumstances happened to be unfavourable.

Isolating things from Earth is an unusual approach these days (it sounds similar to the old 'clean Earth' approach of yesteryear) - most standards these days accept that trying to have separate earths in the same vicinity has lots of disadvantages so mostly take the approach of bonding everything together as thoroughly as possible to minimise impedances and voltage differences. It can demand quite a lot of sometimes quite large bonding conductors though - e.g. if the verticals collectively provide a parallel path to Earth for a PME system (i.e. conductors would have to be sized as main bonding conductors for the entire installation).

   - Andy.

KDY said:

Can you please explain the ref to "safety" in your response?

Circulating currents, causing heating, or EMC issues.

What does the 'comms' do? In some installations, comms is essential for safety, and EMC becomes a safety issue.

Without knowing more about the installation, it's like asking a question without a definitive answer.

Could also be to prevent corrosion of the supports or their fixings due to various frequencies of "noise" on the earthing system ... or even DC.

AJJewsbury said:

One safety implication would be the possibility of differing potentials between the bonded horizontals and unbonded (but Earthed) verticals -- anyone able to touch both simultaneously may be at risk of a shock, if the circumstances happened to be unfavourable.

Depending on the size of the contact area ... but if you're outdoors, isn't that a general problem anyway?

AJJewsbury said:

Isolating things from Earth is an unusual approach these days

Not really when it's done to prevent corrosion ... for example the mounting of most copper earth bars.

Depending on the size of the contact area ... but if you're outdoors, isn't that a general problem anyway?

A minimally complying (to BS 7671) may not have extraneous-conductive-parts outdoors bonded, agreed, so there is a general problem outdoors between exposed-conductive-parts and the general mass of the earth and/or unbonded extraneous-conductive-parts.

In this situation though we presumably have no accessible exposed-conductive-parts (cable armours would normally be sheathed) so a minimally complying arrangement (i.e. bond nothing outdoors) would be relatively safe. But by bonding some but not all of the simultaneously accessible extraneous-conductive-parts it seems to me that there's a possibility that things might have been made worse rather than better (just considering the simple shock perspective of course, other factors would also need consideration).

   - Andy.

AJJewsbury said:

A minimally complying (to BS 7671) may not have extraneous-conductive-parts outdoors bonded, agreed, so there is a general problem outdoors between exposed-conductive-parts and the general mass of the earth and/or unbonded extraneous-conductive-parts.

But we don't know the earthing arrangements, conditions and layout of this site. Some sites have extensive installations of metal pipework and similar in contact with the ground, all of which is bonded, and a suitable global earthing system arrangement, so even outdoors, being able to touch "earthed or bonded things" outdoors is not an issue.

Without seeing the site, it's all speculation.