Steel or PVC?

[Tinyotall]

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

 

[Sintra]

Really depends whether or not you want to give the circuit additional protection by 30mA RCD or not.

 

[Tinyotall]

The circuit has to have RCD by the time i'm finished!

 

[sparks1234]

Really depends whether or not you want to give the circuit additional protection by 30mA RCD or not.

Makes no difference if the capping is steel or plastic, it still needs protection by RCD

 

[johnboy6083]

i reckon sintra miosread it, he prob thought conduit!

 

[yellowvanman]

Steel or pvc - depends on how much protection you need to give the cables from damage. Probably domestic porch PVC would be adequate, if in a machine shop then probably steel would be best!

 

[johnboy6083]

capping only protects the cable from the plasterers trowel. that is it. it offers no other protection, as its designed to be buried under plaster or render. if you were to try and drill through it or hammer a nail through it, you wouldnt even know you had gone through it, until the cable goes bang.

 

[Sintra]

i reckon sintra miosread it, he prob thought conduit!

Yes unfortunately the eyesight isn't quite what it used to be.

 

[johnboy6083]

my speeling is the smae!

 

[madmac]

capping only protects the cable from the plasterers trowel. that is it. it offers no other protection, as its designed to be buried under plaster or render. if you were to try and drill through it or hammer a nail through it, you wouldnt even know you had gone through it, until the cable goes bang.

johnboy6083: You are right that a drill or nail would pass through the capping very easily and it is also the case that an ordinary person could drive a tac with their thumb through capping given enough force! but capping is not there to provide mechanical protection, it is there to provide EEBADS. So, if their is a 30mA, rcd fitted to the circuit then according to BS7671:2008, and as long as the cable is ran in a "safe zone", there is no need for capping but if the rcd fails or is changed to a mcb at a later date, then IMO, I still fit metallic capping and earth it to the nearest socket to give old fashioned EEBADS. Also, IMO. pvc capping is an utter waste of time and money and provides little or no mechanical protection and because it can't be earthed provides no means for ADS what so ever. Not having a go at you mate but you raised a very good point that a lot of sparks are getting lost on.

 

[SPARTYKUS]

Madmac are you having a laugh, capping is to stop to plasterers trowel! Thats all. If you want to fit a flying lead to every off cut of capping so be it!

 

[jaresquire]

Just curious, Madmac, how do you earth the capping (never done it or seen it done myself)

 

[madmac]

Madmac are you having a laugh, capping is to stop to plasterers trowel! Thats all. If you want to fit a flying lead to every off cut of capping so be it!

Who the **** told you that wives tale? Are you serious? Are you having a laugh? Think about what you just said and read up on EEBADS. In fact, don't bother, I've had enough of trying to put across good electrical practise, so if you think that's all capping is for........then fire away big man!

 

[madmac]

Just curious, Madmac, how do you earth the capping (never done it or seen it done myself)

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.

 

[SPARTYKUS]

Good luck with that capping madmac!

Alway been taught that as per other posts. Possibly why plastic version is made too.

Be good if you answered the others' questions just to explain how you go about it.

Hope youre not on the wind up, if not i return your tankard and bid you good day

 

[jaresquire]

Cheers. Wouldn't work with my capping due to all the gaps!
It's usually covered in blood as well.

 

[Tinyotall]

More confused now then when I started! some help!!!

 

[madmac]

Ok boys, it really isnae that hard, think about it for a minute.
You have an unprotected cable( assuming the rcd is ****ed or non-existent), and the ordinary person puts a tac or nail or some other foreign body through the cable!!! It hits the line conductor( live conductor in the good old days), and the ordinary person gets plated!!!!!!!!!!!
OR, the cable is covered with metallic capping which is also earthed by way of a flying lead.......the same situation causes line conductor to initiate a short to earth, which in turn causes an over-load of the the protective device and trips/breaks/fuses the circuit into an isolated/open circuit!!! It really is that simple, or people are seriously misinterpreting basic understanding of electrical practises!!!

 

[Wully]

Agree with madmac we do the same, metal capping over cables gets earth even with the circuit on a RCD. Must be a Scottish thing.

However I changed my mind about the whole thing a few weeks ago, now using pvc. At the end of the day its only for trowel protection.

 

[SMB]

I met someone once who bonded a metal widow frame........

 

[RWJ]

I met someone once who bonded a metal widow frame........

Where did you meet him the window cleaners funeral??

 

[SMB]

smile.

awful.


im presently struggling to explain / understand bonding.


EG....portable large stainless steel kitchen equipment.

I know it doesn't need bonding, the other guy says it does need bonding.

I know it doesn't need bonding

He says yes it does.

I know..........etc. (repeat until bored).



How do I prove im right in me 'thinkings' ?

 

[ian.settle1]

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.

No such thing now it's ADS

 

[madmac]

No such thing now it's ADS

Cheers ian for pointing that obvious fact out!lol. I'm only saying that IMO, I still and so do most guys/mobs I work with, earth the metallic capping and adhere to the now non-existent EEBADS as it is still deemed to be a far superior method of achieving ADS. Maybe only in Scotland though?
And will someone please tell me where in the regs. or any other publication it says metallic capping is only to protect against the plasterers trowel!!!
Maybe this is why "Domestic Installers" don't get taken seriously with clap-trap like this!!!

 

[SPARTYKUS]

Madmac i think you're getting carried away with your capping...


Half the time you don't even need it (because the wall is being dot and dabbed as one example.) what happens then eh.

Also, if its soooo important, i'm assumimg all your bits of capping at continuous somehow.

Also im assuming you cap behind the cable. Walls can have nails driven though them both ways )



I doubt very much it says about the spreads trowel in the regs, im thinking you might be a bit of a winder upper, its been common knowledge for a spark for decades.

 

[madmac]

SPARTYKUS: I'll let all you guys decide on good practise as I'm clearly not making any headway here. lol. I forgot to mention that I don't cap cables ran in safe zones only cables taking an unusual route i.e. diagonal runs or vulnerable runs. I still believe that rcd's can fail and with all the non-sparks wiring up houses and fault finding it will only be a matter of time before one of them replaces a knackered rcbo with a mcb rendering the circuit non-compliant with the 17th edition and leaving vulnerable cables with no additional protection.....unless covered with earthed metallic capping providing 16th EEBADS. Or do you think rcd's are the be all and end all?

 

[SPARTYKUS]

SPARTYKUS: I'll let all you guys decide on good practise as I'm clearly not making any headway here. lol. I forgot to mention that I don't cap cables ran in safe zones only cables taking an unusual route i.e. diagonal runs or vulnerable runs. I still believe that rcd's can fail and with all the non-sparks wiring up houses and fault finding it will only be a matter of time before one of them replaces a knackered rcbo with a mcb rendering the circuit non-compliant with the 17th edition and leaving vulnerable cables with no additional protection.....unless covered with earthed metallic capping providing 16th EEBADS. Or do you think rcd's are the be all and end all?

rcds- yep fail all the time there's a survey by the ECA I think, 3% were found to be faulty

diagonal / unusual runs - ! Lost me there madmac. Last time I checked that had to be in condo (steel, not plastic!) unless buried deep in the wall....... capping no can do, doesn't cut the regulations mustard.

rcbo replaced with mcb - well good luck future proofing everything against a possible future incompetent person, you'll be busy there.

Still think you're a fisherman

 

[madmac]

I was only giving some sound and and relatively low cost advice for good workmanship but it's only my opinion and SELECT and if you think your installs are untouchable then good luck but I'll be continuing good electrical practice even if you think it's rubbish.
diagonal / unusual runs - ! Lost me there madmac. Last time I checked that had to be in condo (steel, not plastic!) unless buried deep in the wall....... capping no can do, doesn't cut the regulations mustard.
As has been stated by me, pvc should not be used! And where does it state that steel conduit must be used for diagonal runs buried in plaster???
As long as you have provided earthed metallic sheathing to vulnerable cables (metallic capping earthed to nearest socket), then the cable has been given additional protection.

 

[geoffa]

don't see how metal capping can be there to provide EEBADS. Cables in walls have to run to equipment in designated zones anyway. No mention in 7671 that i've read that says, (regardless of whether the cable routing is in a special location or not), that metal capping needs to be used and should be supplementary bonded.
I tend to use metal capping on stone walls that are being rendered over as it's easier to fix and bends to the contour of the stones, whereas plastic splits and cracks. Plastic is better for new builds or if the chase in an existing block or brick wall is relatively flat.

Diagonal runs...! hmmm
Why use the 16th edition for earthing arrangements when the 17th edition is the preferred standard maybe someone out there is using extracts from the 13th?
If any one intends changing a faulty RCBO for an MCB they should be a registered electrician and should know better, otherwise they shouldn't be changing it; qualified or not.

 

[telectrix]

diagonal runs with capping? that has got to be a bigger wind-up than big ben.

 

[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