capping cables

[madmac]

I think you're all missing the point about capping.....It offers very little mechanical protection and as has been mentioned before most cables should be ran in "safe zones". Since the 17th edition requires the household to be protected with a 30mA main rcd for premises being used by "normal persons", then the cables are protected to a very high standard/disconnection time. However, this cannot foresee future alterations, e.g. a faulty main rcd at the consumer unit being replaced with a 2 pole main switch by "a friend of a friend"! thus creating in one fell swoop a dangerous installation.......This is where mettalic capping over buried cables which has been EARTHED to the nearest socket will still be adequate as it will give EEBADS. As for using plastic capping for cables buried in plastered walls.....I wouldn't dream of using any form of PVC containment in buried walls as it provides absolutely no mechanical protection and has no value where EEBADS is concerned!!! So it is just a costly non-starter to use pvc containment in plastered walls and the two previous methods are the best practise and safest methods that have passed the test of time.

 

[telectrix]

metallic capping is useles as regards penetration by nails or screws, hardly any better than plastic. if you are going down the route of earthed metallic protection, you're talking galv. steel conduit, thus necessitating deep chases and bonding. best cost effective method is oval tube. and btw, it's not eebads any more.

 

[rmc86uk]

A.D.S

Sent from my HTC Desire using Tapatalk

 

[madmac]

telectrix......"metallic capping is useless as regards penetration by nails or screws".........And your point is exactly? This is why it has to be earthed as it provides no other protection other than ADS. And yes I did quote EEBADS from the 16th edition as I believe it is better practise to continue this practise rather than relying on an rcd for sole protection for disconnection times! And I also think you've gone way of course bringing metallic conduit into the discussion, and as for pvc oval conduit.......there is no need for it if you are running cables in "safe zones" and the household is protected with a main rcd, and the cables that might be deemed to have a greater degree of risk have been covered with earthed metallic capping! I know I'm only an Approved Electrician with 20 years experience and a full apprenticeship behind me not to mention having worked in all sectors of the electrical industry and passed all the required courses to keep up to date with regulations etc. But who am I? I'm just another daft spark that's watching his trade being watered down and good working practise being laughed at!!!

 

[telectrix]

my point is that the wafer thin metal capping is insufficient mechanical protection against nails and screws as they go right through it. sorry about the eebads comment. when i read your post i did not know whether or not you were qualified . was not trying to have a go at you.

 

[andyb]

I know I'm only an Approved Electrician with 20 years experience and a full apprenticeship behind me not to mention having worked in all sectors of the electrical industry and passed all the required courses to keep up to date with regulations etc.

Since when did we start posting our qualifications and experience as part of our argument.
I doesn't help the debate one bit.

I should know I've been posting on forums for over 125 years and have a degree on the subject.

 

[madmac]

Cheers telectrix, sorry about the rant also but as I said I despair at the way the whole industry seems to be heading. You are correct about metallic capping having insufficient mechanical protection and that is my point, it was not intended for that purpose, it was intended to provide EEBADS so that if a "safe zone" was breached with a nail or screw it would first have to pass through the earthed metallic capping before hitting the live cable and thus earthing the nail or screw instantaneously and causing Automatic Disconnection of the overload protective device thanks to Earthed Equipotential Bonding. I know the 17th now says this is not required anymore due to the sensitivity of rcd protection but as I said what if the rcd fails or is replaced with just a 2 pole main switch? Where is the protection for a vulnerable buried pvc insulated cable? It is good practise and costs buttons and takes minutes to install and also gives you peace of mind.

 

[Amp David]

I only ever cap me cable if the cahses are being left unfilled for a while, someone else is doing the plastering afterward or if its a new build where the cables will be left exsposed until the wall is plastered

 

[Engineer54]

Cheers telectrix, sorry about the rant also but as I said I despair at the way the whole industry seems to be heading. You are correct about metallic capping having insufficient mechanical protection and that is my point, it was not intended for that purpose, it was intended to provide EEBADS so that if a "safe zone" was breached with a nail or screw it would first have to pass through the earthed metallic capping before hitting the live cable and thus earthing the nail or screw instantaneously and causing Automatic Disconnection of the overload protective device thanks to Earthed Equipotential Bonding. I know the 17th now says this is not required anymore due to the sensitivity of rcd protection but as I said what if the rcd fails or is replaced with just a 2 pole main switch? Where is the protection for a vulnerable buried pvc insulated cable? It is good practise and costs buttons and takes minutes to install and also gives you peace of mind.

You make some very good arguments here and in your previous post on this thread. I am in complete agreement with you on the good installation practices of our industry being watered down too. Far too much reliance is now being given over to RCDs to provide protection. Perhaps no-one takes any notice of the almost daily posts here, and on other forums, of the failures afforded to these RCD devices...

 

[Deleted member 26818]

It used to be that capping was recommended, as the plaster had an adverse effect on the cables.

 

[telectrix]

but we don't use lime and hore hair any more, though i hear they are trying to promote the use of horse hair at newbury.

 

[RogertheBodger]

Since when did we start posting our qualifications and experience as part of our argument.
I doesn't help the debate one bit.

I should know I've been posting on forums for over 125 years and have a degree on the subject.

I've told you a Million times, don't exaggerate.

 

[RogertheBodger]

but we don't use lime and hore hair any more, though i hear they are trying to promote the use of horse hair at newbury.

Not back in the horehouse are we T?

 

[telectrix]

Not back in the horehouse are we T?

no, but' i'm working on a design for horse shoes with built in RCDs.

 

[malcolmsanford]

I think you're all missing the point about capping.....It offers very little mechanical protection and as has been mentioned before most cables should be ran in "safe zones". Since the 17th edition requires the household to be protected with a 30mA main rcd for premises being used by "normal persons", then the cables are protected to a very high standard/disconnection time. However, this cannot foresee future alterations, e.g. a faulty main rcd at the consumer unit being replaced with a 2 pole main switch by "a friend of a friend"! thus creating in one fell swoop a dangerous installation.......This is where mettalic capping over buried cables which has been EARTHED to the nearest socket will still be adequate as it will give EEBADS. As for using plastic capping for cables buried in plastered walls.....I wouldn't dream of using any form of PVC containment in buried walls as it provides absolutely no mechanical protection and has no value where EEBADS is concerned!!! So it is just a costly non-starter to use pvc containment in plastered walls and the two previous methods are the best practise and safest methods that have passed the test of time.

telectrix......"metallic capping is useless as regards penetration by nails or screws".........And your point is exactly? This is why it has to be earthed as it provides no other protection other than ADS. And yes I did quote EEBADS from the 16th edition as I believe it is better practise to continue this practise rather than relying on an rcd for sole protection for disconnection times! And I also think you've gone way of course bringing metallic conduit into the discussion, and as for pvc oval conduit.......there is no need for it if you are running cables in "safe zones" and the household is protected with a main rcd, and the cables that might be deemed to have a greater degree of risk have been covered with earthed metallic capping! I know I'm only an Approved Electrician with 20 years experience and a full apprenticeship behind me not to mention having worked in all sectors of the electrical industry and passed all the required courses to keep up to date with regulations etc. But who am I? I'm just another daft spark that's watching his trade being watered down and good working practise being laughed at!!!

As soon as I read these wildly differing quotes I had to respond to this. As for your 20 years in the trade your still a boy at it.

Having trained down a coal mine, worked in hospitals, factories, high rise buildings, petro chemical plants, etc, etc etc and domestic homes I can safely say that unless the designer for some unknown reason insisted on it, I have yet to see buried T+E cable in a domestic situation run in earthed metalic capping, and that is before the advent of RCD being used for additional protection.

I have indeed run metal conduit in a domestic home as the designer wanted it, and the designer get's what he wants, but be assured I would never design a domestic home using earthed metal anything unless there was a very good reason to. And that is not a deteriation in standards that is common electrical practice.