Sy flex armour used as cpc

Bakkiesmat · Jan 27, 2011

Hi all i am in the process of doing a pir on a residential home and they have some 3phase sockets wired in 4 core sy flex using the cpc as the neutral and the sy flex " armour" as the cpc. Obviously im going to fail the circuits for using the cpc as the Neutral but just wondering about the armour/cpc. As on sy flex its more of a braiding than a proper armour

Cheers

nickblake · Jan 27, 2011

Firstly the CPC should never be used as a live conductor , and also on an SY flex the armour is no way good enought for a CPC this should be used as protection only , you are 100% correct ,these cables should be changed and a cable with the correct number of required cores used

Bakkiesmat · Jan 27, 2011

Thank you this is what i thought the circiut was installed in 2004 and has had a pir done since by another company and was not picked up

Darkwood · Jan 27, 2011

Also to note is the braiding must be earthed too but not used as mentioned above as a functional earth, the no' of times ive seen it utilised as an abrasion resistance without it been earthed is unbelievable, to be noted also its original design is as a screening for interference which would normally be grounded but years on the market have found it been used for other jobs which i dont see an issue but as long as it is installed correctly and safely and this is where many fail. I have also seen it used on exterior jobs and if i recall the manufacturers say it is not to be used for outside installations.

nickblake · Jan 27, 2011

darkwood said:
Also to note is the braiding must be earthed too but not used as mentioned above as a functional earth, the no' of times ive seen it utilised as an abrasion resistance without it been earthed is unbelievable, to be noted also its original design is as a screening for interference which would normally be grounded but years on the market have found it been used for other jobs which i dont see an issue but as long as it is installed correctly and safely and this is where many fail. I have also seen it used on exterior jobs and if i recall the manufacturers say it is not to be used for outside installations.

!00 % agree screening couldnt for the life of me remember the word ,lol , thanks for filling in the bits id missed

sysrq · Sep 21, 2015

darkwood said:
Also to note is the braiding must be earthed too but not used as mentioned above as a functional earth, the no' of times ive seen it utilised as an abrasion resistance without it been earthed is unbelievable, to be noted also its original design is as a screening for interference which would normally be grounded but years on the market have found it been used for other jobs which i dont see an issue but as long as it is installed correctly and safely and this is where many fail. I have also seen it used on exterior jobs and if i recall the manufacturers say it is not to be used for outside installations.

The steel braid of SY cable was never intended to be used as a screen, it's just a mechanical protection and to blow fuses when cable gets damaged (when steel braid is earthed). If you want screening for interference then you have a CY cable with tinned copper braid which must be used with a 360 degree connection glands. For additional mechanical protection it can be used with plastic or metallic flexible conduits.