ITC suite at primarey school

[davetherave1979]

Hi Guys had a look at this job today 30 computer stations they dont have computer towers at each desk just a monitor and a box that talks back to the main server going to split the circuits up got to fit a new db and will fit rcbos to each circuit would I be best wiring 20 amp radials or 32 rings there isnt much load. there will be 6 circuits around the room I was going to wire in 4mm te and run a clean earth circuit to each circuit in 4mm singles as this will be for the high protective conductor does this all sound correct.

Normally only do domestic and small commerical work havent wired a ITC suite before as work is dead I need this job and they say there is more through the holidays.

Any help would be great:rolleyes2:

 

[PC Electrics]

If you wire the sockets as RFCs you will not need to add any extra cpc, just use sockets with two earth terminals. If you do it as a radial you'd need to wire a 10mm g/y back from the end - £££s.

Keep the RFCs small with just a few sockets on each. I don't know what the guidlines are but I would have thought it best to try and keep the cpc current down to about 15mA. I find most RCBOs trip at about 23 - 25mA, whereas RCDs seem to be around 27mA.

If you fuse the RFCs at 20A you only need a cable capacity of 12.5, so 2.5 t&e in RM101 (17A) will be fine. Even at 50%, 2.5 is still 13.5A.

 

[davetherave1979]

Thanks when I spoke to the elecsa help line the man said I need to run a separet clean earth to the sockets on the second earth terminal min 4mm

 

[telectrix]

if it's a RFC, then you don't need a separate 4mm cpc. that's only for a radial. with a RFC you need to use the socket faces with 2 earth terminals and split the cpc's at the DB into separate terminations. see previous threads for hi integrity earthing.