Parallel earth paths and design

[Eric12]

Rack ? you mean like a shelves holding the UPS's. Sorry you lost me there

 

[pc1966]

Rack ? you mean like a shelves holding the UPS's. Sorry you lost me there

This sort of thing:

Server Rack Cabinet

This Product Ships Freight

www.racksolutions.co.uk

Most servers and other professional equipment is designed for the 19" spacing fixing, though there are other sizes now.

 

[Eric12]

In one case I had 6 final circuits going to a set of 6 x 19" racks, so just had two CPCs, each of the same 4mm size as needed for the CPC. The racks were all bolted together and the CPCs from a common block (so 2 CPC to block, 6 from there to each 5kVA UPS).

Yea thats all good, never touched that sort of cabinetry !

 

[DPG]

I agree that an independent cable cpc is easier all round for sure, maybe a waste of cable in some instances, but maybe more safer and idiot-proof as a result. My point for posting was to consider a large scale building with each circuit using the metalwork of the structure for CPC connection, and would that be an option ? The reason being to save money on cabling.
You see, call me an optimist, but I can imagine in the far future that alot of devices and equipment will be super low voltage where connection to earth would be without cables atall, just place it anywhere where the structure is earthed. I know its a bit sci-fi but its imaginable !

But at such low voltages you probably wouldn't need an earth connection.

 

[pc1966]

The thing with distributing ELV power is the much higher impact of voltage drop, not to mention the higher relative level of any induced noise. So I suspect we will still be sending 230V around the building but maybe have more multiple USB-like outlets for stuff that just needs a few W at 5V or similar.

 

[Eric12]

Yeah it's amazing really. More brighter people than me must have thought about it all; who would have thought 20 years ago that a phone could be charged for example without even plugging it in !

 

[rikkic]

I have just fitted some tray work supported from the purlins above and threaded stud. To the tray I have bolted 5x 10 way klik boxes, which have a metal slot in them for easy attachment which must be earthed. I am now struggling to get an r2 reading (0.01-0.02ohms) !
My question is, should I remove cpcs from klikboxes, wago them together and re-test? Or just leave as it is and document original reading?

 

[timhoward]

I have just fitted some tray work supported from the purlins above and threaded stud. To the tray I have bolted 5x 10 way klik boxes, which have a metal slot in them for easy attachment which must be earthed. I am now struggling to get an r2 reading (0.01-0.02ohms) !
My question is, should I remove cpcs from klikboxes, wago them together and re-test? Or just leave as it is and document original reading?

Is the low path back to the MET coming via the bonding of the tray and then through the tray itself?
Would removing tray bonding during continuity testing help?