• IMPORTANT: Please note that nobody on this forum should be seeking from or providing advice to those who are not competent and / or trained and qualified in their field (local laws permitting). There is a discussion thread on this global industry-wide matter HERE. This also has more information about the warning with regards to sharing electrical advice in some countries. By using this forum you do so in agreement to this.

Discuss Just had full rewire done, cables very close to surface or coming through skim in the Electrical Forum area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

As for gas bonds etc, do they need to be in a zone? I know it'll be classed as 'good practice' to do so, but they aren't a live cable so do they strictly need to be installed in a zone?

debateable. i would say yes, run in zones, basically to protect from damage by drilling etc. this could potentially lose a bond to extraneous services.
 
I don't have the byb on me as not at home but iirc the relevant reg (522 something I believe) specifies a bs number that the earthed metallic containment must meet the requirements of as it's expected to be penetrated hence having to meet the requirements of a protective conductor. From my point of view earthed metallic capping is not satisfactory. One other option the reg gives us is that if the cable is burried in a wall at a depth of less than 50mm then RCD protection can be ommited if it has sufficient mechanical protection to stop the penetration of nails screws and the likes of.

In the absence of a relevant product standard, e.g. British Standard, the designer should obtain suitable evidence from the manufacturer that any product selected for the purpose is suitable to prevent penetration by nails, screws and the like.

As an example, steel of 3 mm minimum thickness is generally considered to provide sufficient mechanical protection, except where shot-fired nails or similar fixing methods are likely to be used. I did post a video once from clarkson Evans which shows some thick metal capping that he drills, hitting a nail through etc to no avail but can't seem to find it. The key thing is that sufficient mechanical protection doesn't need earthing where as other methods require earthing.....Cables can be run out of zones as long as they have sufficient mechanical protection.
 
Last edited:
In our new build the tails run about 8m. The run in the wall where it goes up to the ceiling void is protected by metal capping that is bonded.

As for gas bonds etc, do they need to be in a zone? I know it'll be classed as 'good practice' to do so, but they aren't a live cable so do they strictly need to be installed in a zone?
Never assume a bonding conductor will not be live even though in normal circumstances it is not.
 
I don't have the byb on me as not at home but iirc the relevant reg (522 something I believe) specifies a bs number that the earthed metallic containment must meet the requirements of as it's expected to be penetrated hence having to meet the requirements of a protective conductor.

Hi - yes, it's 522.6.204 that refers to an earthed conduit (per BS EN 61386-21) or trunking (per BS EN 50085-2-1) for cables in walls to avoid RCD. Or use SWA (per BS5467 +).

There is option to use a mechanical protection that is not to a BS, but we would be responsible to ensure it was at least as good as the protection offered by the others. I think conduit was 1/8" wall thickness which became 3mm in metric land which may be origin of Lee's "steel of 3mm min" recommendation (?) . But not having any conduit to hand (shocking admission) this could be complete rubbish :)
 
I did post a video once from clarkson Evans which shows some thick metal capping that he drills, hitting a nail through etc to no avail but can't seem to find it.
You did indeed Lee, I nearly got some but it was a bit pricey, in the end I got a local smithy to cut me some lengths of 4mm plate steel, does a good job as well.
 

Reply to Just had full rewire done, cables very close to surface or coming through skim in the Electrical Forum area at ElectriciansForums.net

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top