Small Data Cabinet Conundrums

[lozarus]

Been asked to supply an FCU for a data cabinet. Sounds simple right? Not a huge server room style thing, just a small 6U data cabinet mounted on a wall containing a network switch, CCTV recorder and a 6-way 13a PDU

I've seen these done in a variety of ways but not sure what's best to do. My first query is regards bonding of the cab:-

Once the equipment is loaded it will be "indirectly" connected to earth via the 1.5mm flex from the PDU.

However I've also seen these cabinets installed with a 4mm Earth taken back to the MET.

I could test it to see if it's extraneous - but I don't see how you can rely on this as it will naturally be earthed by the equipment within. I can't find anything that outlines whether the cab should be bonded.

My scenario gets a little trickier still:-

It's located in an outbuilding. Fed by 6mm T&E buried in pipe installed many years ago but has a modern Hager RCBO board inside the outbuilding. So my incoming cpc is just 2.5mm anyway.

Further to this there is a buried CAT6 coming from the house which will plug into equipment in the cabinet. I'm concerned this could bring in some differing earth potentials from the house end. I'll confess to not having had a look at the supply end yet but I'm assuming the house is TNCS and it's carried out to the garage.

Not sure if Im overthinking this but unsure what route I should follow regards bonding this?

 

[cliffed]

Tricky the supply may be suitable, for the actual load required which seems minimal.
If it’s on a TNCS then this may be allowed in this instance, with the correct protection devices.
Rcbo for the IT Cab, hopefully the building does not contain any metallic parts, if it does then MPBC would have to be sized accordingly.
Cat6 cabling the screen for that cable would be terminated into the IT Cab, the earths would be hopefully @ the same potential from the house to your out building, it’s from the same supply.
No extraneous parts are present?

 

[westward10]

You are overthinking it.

 

[Avo Mk8]

As above.
Ethernet has no ground. The differential signals are galvanically isolated.
All depends on what RJ45 connectors are used as to whether the CAT 6 cable screen provides earth continuity, or is even connected, but it's not required for signal transmission.

Edit: I guess there might be EMC filters in devices or ethernet switches in the circuit, resulting in a bit of capacitance coupling "equipment ground" one end to "equipment ground" the other, but the current that could flow would surely be miniscule.

 

[lozarus]

Thanks. I think I'll just put the FCU in as requested. To be fair I've only seen the additional bonding thing when specified by data companies

 

[plugsandsparks]

Some networking equipment mandates a separate earth to the chassis, Cisco Catalyst Edge 8200 series springs to mind, lol
I cannot see a problem running a separate earth out of the same FSU and connecting to the bonding point on the rack, then any comms engineers can use it for specific equipment that mandates it.