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Topic Title: High Integrity Question
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Created On: 24 July 2013 07:24 PM
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 24 July 2013 07:24 PM
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fraserd

Posts: 106
Joined: 25 July 2008

Hi, Just after some advice ive used the search and had a read up but still havent found a definate answer. I have a computer room to wire up containing 20 computers, im wiring three individual circuits for these due to CPC leakage currents, but im after some advice on the best option for wiring it up, cabling in ceiling void with no mechanical protection then into dado trunking. i was going to pull in 2.5mm t&e rings for each bank of circa 7 pcs plus a 4mm CPC singles ring but can i use this 4mm ring for all 3 circuits to comply with regs regarding high integrity. Thanks.
 24 July 2013 07:25 PM
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sparkyaj

Posts: 57
Joined: 04 June 2012

Some really good info in the IET design guide that covers this.
 24 July 2013 07:34 PM
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fraserd

Posts: 106
Joined: 25 July 2008

Bugger, havent got it
 24 July 2013 07:52 PM
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weirdbeard

Posts: 1652
Joined: 26 September 2011

Originally posted by: fraserd

i was going to pull in 2.5mm t&e rings for each bank of circa 7 pcs plus a 4mm CPC singles ring but can i use this 4mm ring for all 3 circuits to comply with regs regarding high integrity. Thanks.


As far as i know, if the terminations are all correct for a rfc theres no need need for any additional cpcs.
 24 July 2013 08:52 PM
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24Hour

Posts: 194
Joined: 06 April 2006

Aggredd with weird beard.

Also the actual leakage current of modern pc,s without crt monitiors is about 1ma per 3 pc,s.

Well thats the reading i got after a large school data room refit i done last year.

-------------------------
Yes i do do 24/7 everyday of the FLAMIN year.
 24 July 2013 10:00 PM
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fraserd

Posts: 106
Joined: 25 July 2008

What do you mean by if the terminations are all correct for rfc? I'm assuming you mean it's acceptable aslong as its wired as per high integrity by using the seperate cpc terms on skts and db?
I did think that leakage wouldn't be as high as the 3.5ma quoted on modern pcs but knowing this place they will put prehistoric ones in.
 24 July 2013 10:56 PM
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Cremeegg

Posts: 544
Joined: 13 July 2007

Agreed with 24Hour - actual measured leakage current on a room I did with two banks of 11 workstations on two circuits was around 5mA. Even with some old kit connected we couldn't get the level above 8mA. It seems like a requirement that's almost been overtaken by technology.
 25 July 2013 07:54 PM
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Zs

Posts: 3037
Joined: 20 July 2006

Originally posted by: weirdbeard

As far as i know, if the terminations are all correct for a rfc theres no need need for any additional cpcs.


Until something develops a fault maybe? High Protective conductor currents come to mind.

Fraser, your comment on the installation method has caught my eye. If you are going to go direct into the ceiling void can I please urge you to consider adequate fire proof cable support (not necessarily the cable itself) so that the false ceiling is not acting as support. Most of the offices where I am finding rogue voltages have a birds' nest above the smart ceilings. Whilst the rest of the environment is always top dollar, the behind the scenes work is shoddy.

I think it is time we all smartened up our acts and rise above the near-traditional low standards of out of view installation.

And watch out for asbestos up there.

Zs
 25 July 2013 09:10 PM
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weirdbeard

Posts: 1652
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Originally posted by: fraserd

What do you mean by if the terminations are all correct for rfc? I'm assuming you mean it's acceptable aslong as its wired as per high integrity by using the seperate cpc terms on skts and db?
.



 25 July 2013 09:18 PM
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weirdbeard

Posts: 1652
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Originally posted by: Zs

Originally posted by: weirdbeard

As far as i know, if the terminations are all correct for a rfc theres no need need for any additional cpcs.



Until something develops a fault maybe? High Protective conductor currents come to mind.



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