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Comms Rack Earthing and Bonding Question

me1899
Hi all


First post here, so apologies if I make any faux pas


I have a query on comms rack bonding (design stage).


- Two fibre services incoming to a big warehouse plus copper lines entering to a 42U cabinet in a small comms room on first floor of an attached little office area.

- MET is in the warehouse itself, in a corner (630A TPN supply).

- Fibre links from there to 5No. satellite racks (12U) on warehouse walls, 

- Satellite racks feed CCTV and WIFI in warehouse

- Light comms equipment install in the racks only.

- Furthest rack 240m away from MET (260m from comms room).


My question is about earthing and bonding to BSEN 50310.


Am I right in thinking that each satellite cab is to have a 4mm g/y to a brass earth block adjacent (secondary bonding busbar) and then connection onto a 16mm conductor back to a primary bonding busbar which in turn connects to the MET? Am finding the standard a little confusing. 42U to have a 16mm connection?


I see a table about sizing based on distance, but is that applicable?


Sorry if I am being dense, but finding it hard to understand. Help would be appreciated or direction to a simplified resource.


Regards


Muhammad







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  • 0
    HI me1899 you said, "Am I right in thinking that each satellite cab is to have a 4mm g/y to a brass earth block adjacent (secondary bonding busbar) and then connection onto a 16mm conductor back to a primary bonding busbar which in turn connects to the MET? Am finding the standard a little confusing. 42U to have a 16mm connection?"


    Please consider I'm no expert on earthing and bonding - but I'd suspect that if your warehouse is made of a metal framework structure, and  bonding needs to run back to the MET somehow, you could consider using this metal framework - so no need for giant scissor lifts and running hundreds of meters of earth all over the warehouse (huge additional cost) to get back to the MET, just connect any underfloor rack bonding if required to the metal frame of the building. This in turn is connected to the MET. 


    Kind Regards


    Tatty
Reply
  • 0
    HI me1899 you said, "Am I right in thinking that each satellite cab is to have a 4mm g/y to a brass earth block adjacent (secondary bonding busbar) and then connection onto a 16mm conductor back to a primary bonding busbar which in turn connects to the MET? Am finding the standard a little confusing. 42U to have a 16mm connection?"


    Please consider I'm no expert on earthing and bonding - but I'd suspect that if your warehouse is made of a metal framework structure, and  bonding needs to run back to the MET somehow, you could consider using this metal framework - so no need for giant scissor lifts and running hundreds of meters of earth all over the warehouse (huge additional cost) to get back to the MET, just connect any underfloor rack bonding if required to the metal frame of the building. This in turn is connected to the MET. 


    Kind Regards


    Tatty
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