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.
I think that Andy has also made an error worrying about direct contact with damaged cables etc by anyone. Whilst that could happen given enough various circumstances, realistically it is very very unlikely. I would point out that a single RCD for a rack of servers (which might take 100A of mains, probably 3x32A supply) would be foolish, the idea of fitting one each is worse! We have an electrical system which depends on proper earthing of exposed conductive parts, and automatic disconnection of supply by CPDs, yet this regulation is determined to fit even more unnecessary RCDs! The scope for RCD protection is way too wide, it should only be for sockets where portable appliances are likely to be used by unskilled persons, and the servers in a rack should be out of scope for portable appliances separately, as you need tools to make them portable
I agree RCDs aren't the solution - but I don't agree that the risk can be just ignored either. I've seen too many IT racks where things had obviously been put together in a very hap-hazard way, with everything from extra sockets provided by dangling supermarket 4-way extension leads, leads trapped in doors or slide rails, to mains leads with core insulation exposed. Pretty much all the horrors you see in some domestics. Also I don't think they're really in the usually-not-handled-when-live class of fixed appliances either - so much is hot swappable these days (usually PSU and fan modules are - some even allow hot addition of processors and memory) - and the idea of switching off before sliding a server out of the rack, or shoving an arm through the tangle of cables at the back to pull another lead through, just wouldn't be a consideration. If anything a restrictive conductive location might be a closer approximation. Like I said, I agree that 30mA RCDs aren't the answer, but I do see the risk assessment as a means of chivvying management into making sure their IT staff actually have a bit of basic electrical safety knowledge and implement some basic good practices.
I think that Andy has also made an error worrying about direct contact with damaged cables etc by anyone. Whilst that could happen given enough various circumstances, realistically it is very very unlikely. I would point out that a single RCD for a rack of servers (which might take 100A of mains, probably 3x32A supply) would be foolish, the idea of fitting one each is worse! We have an electrical system which depends on proper earthing of exposed conductive parts, and automatic disconnection of supply by CPDs, yet this regulation is determined to fit even more unnecessary RCDs! The scope for RCD protection is way too wide, it should only be for sockets where portable appliances are likely to be used by unskilled persons, and the servers in a rack should be out of scope for portable appliances separately, as you need tools to make them portable
I agree RCDs aren't the solution - but I don't agree that the risk can be just ignored either. I've seen too many IT racks where things had obviously been put together in a very hap-hazard way, with everything from extra sockets provided by dangling supermarket 4-way extension leads, leads trapped in doors or slide rails, to mains leads with core insulation exposed. Pretty much all the horrors you see in some domestics. Also I don't think they're really in the usually-not-handled-when-live class of fixed appliances either - so much is hot swappable these days (usually PSU and fan modules are - some even allow hot addition of processors and memory) - and the idea of switching off before sliding a server out of the rack, or shoving an arm through the tangle of cables at the back to pull another lead through, just wouldn't be a consideration. If anything a restrictive conductive location might be a closer approximation. Like I said, I agree that 30mA RCDs aren't the answer, but I do see the risk assessment as a means of chivvying management into making sure their IT staff actually have a bit of basic electrical safety knowledge and implement some basic good practices.
