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RCD Protection at Data Cabinets

Bob Cowie
I have a Client that will not provide a Risk Assessment to omit an RCD Commando Socket for a Data Cabinet. He wishes to employ a local isolator for the Cabinet, however he is concerned that the PDU Strip that arrived on site from the factory and pre-fitted within the data cabinet would still need an RCD. It is my opinion that the Factory built Data Rack is classed as a piece of equipment and as such does not form part of the Contractor's installation. If the Rack had arrived on site without the PDU strip fitted and it was installed by the Contractor then this would form part of the installation and therefore would require an RCD. Any advice/assistance would be appreciated.
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    AJJewsbury:


     


    Same with plug and socket-outlet. They're all just isolators.



    Sorry, but I've got to disagree with that. Plugs & sockets mean that IT technicians and change the power supply arrangements safely. Bare in mind that when something goes wrong with live (i.e. customer facing) systems in the IT world there is huge pressure on technicians to get things working as quickly as possible - calling in an electrician who might not turn up for a few hours simply isn't an option. Being able to unplug a rack from one supply and plug it into another nearby supply has saved things on my watch at least once.


      - Andy.

     




    Well ... the original discussion point was that it was easy to get "mixed up" with an isolator, and that is what I was answering.


    I definitely get the point about quickly connecting to another supply, but of course that may mean making a decision whether it's safe to do so.


    It is still the case that making an assembly that doesn't really meet BS EN 61140 (in that the protective conductor current is too high, evidenced by the fact you can't use a 30 mA RCD) and then trying to treat it as a 32 A (or less) pluggable appliance, doesn't quite stack up. Basically, for pluggable equipment, the limit in BS EN 61140 for protective conductor current with rating > 20 A is 10 mA. To exceed this limit, the equipment should be permanently connected, AND have a reinforced protective conductor, AND be limited to a protective conductor current of 5 % of the phase current.


     

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  • 0

    AJJewsbury:


     


    Same with plug and socket-outlet. They're all just isolators.



    Sorry, but I've got to disagree with that. Plugs & sockets mean that IT technicians and change the power supply arrangements safely. Bare in mind that when something goes wrong with live (i.e. customer facing) systems in the IT world there is huge pressure on technicians to get things working as quickly as possible - calling in an electrician who might not turn up for a few hours simply isn't an option. Being able to unplug a rack from one supply and plug it into another nearby supply has saved things on my watch at least once.


      - Andy.

     




    Well ... the original discussion point was that it was easy to get "mixed up" with an isolator, and that is what I was answering.


    I definitely get the point about quickly connecting to another supply, but of course that may mean making a decision whether it's safe to do so.


    It is still the case that making an assembly that doesn't really meet BS EN 61140 (in that the protective conductor current is too high, evidenced by the fact you can't use a 30 mA RCD) and then trying to treat it as a 32 A (or less) pluggable appliance, doesn't quite stack up. Basically, for pluggable equipment, the limit in BS EN 61140 for protective conductor current with rating > 20 A is 10 mA. To exceed this limit, the equipment should be permanently connected, AND have a reinforced protective conductor, AND be limited to a protective conductor current of 5 % of the phase current.


     

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