Metal conduit

[ColJack]

What about steel capping? If it can be properly earthed, would that fulfill the requirements for nonRCD concealed cables?

no it would not.. it has to surround the cable on all sides, including the side facing the wall.. you even say so yourself in the next post you made..

In what way would it not comply? The cables would be surrounded by an earthed metallic covering....

see?

I think I might just do away with cabling completely and fabricate a bussbar system from copper pipe.

wouldn't that be nice, a 3 bar busbar chamber set at 450 from the floor.. you'd just have to clip in your sockets where you want them..

If you want to use copper to provide your earthed metallic covering then install MICC....

hmmm, singles in copper pipe = MICC equivalent... ? 2 ( or more ) coper conductors surrounded by insulating material inside a copper tube..

 

[1john]

i wouldn't fancy packing the magnesium oxide in after

 

[NotHimAgain]

Copper and aluminium conduit have been used in the past. They would both probably comply with BS EN 61386 as this applies to all conduit including plastic.

To meet section 522 (impact) the conduit must meet the requirements of BS 7671 for a protective conductor. Copper and aluminium could do that.

I understand that copper conduit has been used in the Palace of Westminster - but I have not seen it. I have seen aluminium.

 

[ban-all-sheds]

I saw a conservatory once at some stately home (you know the sort of thing - a conservatory bigger than most peoples' houses), and they were using copper pipe as conduit for the wiring, and had left it to develop mottled verdigris - it toned in very well. They appeared to be using regular tank connectors as bushes where the conduit entered metalclad boxes - it was a shame that they hadn't had some of those made in copper....

 

[LoveRocket]

To meet section 522 (impact) the conduit must meet the requirements of BS 7671 for a protective conductor.

What about using cable incorporating a metal braid/screen but not listed explicitly in the list of permitted BSxxxx cables (for nonRCD use) in BS7671.

For example, could you use shipboard cable if you could show that the braid meets the requirements for a protective conductor? (and is this as simple as determining the combined CSA (and type) of the braid)

 

[NotHimAgain]

Section 522 lists various cables and their related standards - it requires that the cable used complies with one of the listed standards.

Any cable not included there would have to be tested for compliance against one of the given standards.

The only alternative would be to invoke 511.2 and claim that your proposed cable offers an equivalent standard of safety. However, this is not an easy path, as you could be required to prove your assertion. For example, you might have to show that the cable can pass a nail penetration and fault clearance test (See BS 8436) at some specified fault level.

Self certification is generally not a cost effect solution.

 

[ColJack]

what about sections 120.4 New materials and inventions.

 

[ban-all-sheds]

Will that be the regulation which requires you to certify you have exercised reasonable skill and care in evaluating the properties of the new materials and that to the best of your knowledge and belief they are at least as safe as the ones which comply with the regs?

 

[ColJack]

yes but not in those words...

I don't see any difference with using singles in copper pipe than using alitube or similar cable.. it would be an earthed metalic sheath so it complies, it doesn't have to satisfy the impact properties to do that..

 

[NotHimAgain]

It depend what you mean by 'satisfy the impact properties'.

The cables, conduits and trunkings listed do not prevent damage due to impact, and do not have to resist penetration. What they do have to do is stay intact long enough for a fault to clear after penetration - so if the standard they are constructed to requires such a test, it is for nail penetration and fault clearance - not just penetration.

The BS 8436 cable you refer to as alitube is probably the least effective at meeting this requirement - for that reason its application is limited to a maximum fault level (it used to be quoted as 170A).

The only system that resists impact is mechanical protection sufficient to prevent penetration by nails screws and the like - but that depend s on what is driving them .

 

[ban-all-sheds]

yes but not in those words...

But when you sign the EIC that's what you are saying you have done if you are not using materials which comply with a recognised standard.

I don't see any difference with using singles in copper pipe than using alitube or similar cable.. it would be an earthed metalic sheath so it complies, it doesn't have to satisfy the impact properties to do that..

Whether you, or I can see any difference does not change the fact that 522.6.6 (i) requires cables with an earthed metallic covering to be one of a list of particular types, that (ii) & (iii) specify BSs which copper pipe doesn't comply with and that (iv) calls for mechanical protection.

I'm sure that singles in copper pipe would be just as well, or better, protected than the cores in alitube or pyro (ha - you could use microbore pipe and pretend it was pyro ), but you would have to show that you had carried out a proper analysis, and documented it, not just said "must be OK".

csa of the pipe to verify cpc suitability and wall thickness compared to alitube and pyro should do it. Maybe resistance measurements to show that compression joints maintain proper continuity. Probably give the PTFE tape a miss.

Gotta wonder why though, when copper pipe is more expensive than steel conduit....

 

[ColJack]

compression? I was thinking solder joints..

 

[flameport]

csa of the pipe to verify cpc suitability

Easily big enough, even with 0.5mm walls, a 15mm diameter copper pipe has a csa of around 22mm.

 

[ban-all-sheds]

Oh, absolutely.

All I'm saying is that you should document having worked that out, as there is nowhere to look it up, to show that you had exercised reasonable skill and care...