Steel or PVC?

[Tinyotall]

Need to first fix a porch, does it matter which capping I use? PVC or Steel?

 

[madmac]

Select has issued for a number of years now a diagram for safe zones to run cables and it also points out that diagonal runs albeit unusual are sometimes used and this instance it is preferred to use earthed metallic capping.
I'm obviously not getting anywhere here so I'll just leave it up to you guys to decide.

 

[madmac]

Ok guys you've made me pull out my notes and here it is: Permitted cable zones: BS 7671:2008 Regulations 522.6.6 and 522.6.7
Earthed metallic covering or mechanical protection required unless cable depth is 50mm or more.......this is for DIAGONAL runs.

 

[telectrix]

read 522.6.6. again. nowhere does that reg. mention diagonal runs. sse part (v) .

 

[madmac]

See part (i), of 522.6.6 where cables that are less than 50mm beneath the surface must be protected by earthed metallic sheathing and as regards to (v), I never said to use earthed metallic sheathing for cables ran in safe zones i.e. 150mm from ceiling or 150mm from angle of adjoining walls! Try to understand that I am pointing out good electrical practice for unusually ran cables which are neither in safe zones or buried deeper than 50mm! But of course it's up to the electrician to decide whether or not to rely on the use of an rcd for properties under ownership of ordinary persons or whether it would be thought wise to protect vulnerable cables by additional protection of earthed metallic sheathing, re. the original post which could be classed as an unusual cable run.

 

[Electricalserv]

See part (i), of 522.6.6 where cables that are less than 50mm beneath the surface must be protected by earthed metallic sheathing and as regards to (v), I never said to use earthed metallic sheathing for cables ran in safe zones i.e. 150mm from ceiling or 150mm from angle of adjoining walls! Try to understand that I am pointing out good electrical practice for unusually ran cables which are neither in safe zones or buried deeper than 50mm! But of course it's up to the electrician to decide whether or not to rely on the use of an rcd for properties under ownership of ordinary persons or whether it would be thought wise to protect vulnerable cables by additional protection of earthed metallic sheathing, re. the original post which could be classed as an unusual cable run.

There is no need for earthed metallic capping if its RCD protected though. No need at all

 

[madmac]

I'm actually in agreement with you Electricalserv, I was only saying that in some circumstances it may be wise to add a little bit more protection when dealing with ordinary persons households. If at least for future proofing against bodge repairs and giving peace of mind.

 

[telectrix]

and what i am saying is that if cables are run outside of safe zones,e.g.diagonally, the stell capping , even if earthed, is not sufficient protection against penetration by nails or screws. only steel conduit is acceptable in such a case, and of course, the conduit must be earthed. ( 522.6.6, (i) complies with the requirements of these regulations for a protective conductor of the circuit concerned. )

 

[yellowvanman]

As has been said by some when running cables outside the safe zones and not at a depth >50mm then the cable:

i) Shall incorporate an earthed metallic covering - it then goes on to mention a number of BS numbers for cables - included in that list is SWA, MIC and pre-wired conduit, or
ii) be enclosed in earthed conduit complying with BS EN 61386, or
iii) be enclosed in earthed trunking or ducting complying with BS EN 50085, or
iv) be mechanically protected against penetration of nails - usually menas a steel sheet of at least 3mm

No where in the above does earthed metal capping meet any of the above requirements.

 

[Guest 004]

jaresquire: All you do is take a flying lead of 2.5mm earth cable from one of the fixing points of the capping to the socket outlet/light fitting/light switch earthing terminal and in a matter of seconds you have provided EEBADS to the capping and protected the buried cable, simple really but lost on some guys who seem to think this is a major project of some description but thanks for taking an interest anyway mate.

what a load of bollards

 

[johnboy6083]

i understand what your saying masdmac about eebads, but IMO, you wouldnt get a path of low enough impedance with capping to acheive automatic disconnection of supply. i asked my lecturer when doing 17th about using capping and he said not a chance. Lecturers are not always right, but in this instance i happen to agree.

 

[redrocket10000]

I reckon the only purpose of plastic capping, is to prevent cement products covering cables from breaking down the cable insulating material, i've found this to be true when the wall containing the cable is continuously damp and thus the lime in cement product reacts with the moisture and becomes acidic. Apart from that i can see no reason to use plastic. Imo