Ban the sale of twin and earth ? ?

[bernardgreen]

Should the sale of " twin and earth " be banned under trades description act and instead be sold as " twin and CPC " or other description not using the word "earth" unless it is being sold specifically for use in a TT system.

I noticed the last reel of 2.5 is labelled 2 x 2.5 + 1 x 1.5 no mention of earth


Should there be different colours of sleeving for CPC derived from a PME supply and CPC connected to an earth rod and therefore a genuine earth.

Blue wires that mighr be live must be sleeved brown and not just labelled "switched live" so by the same reasoning an earth that can be safely exported outside the equipotential zone should be marked differently to an "earth" that cannot be exported outside the equipotential zone.

 

[PrenticeBoyofDerry]

I don't think there should be or I am going to have to spend a sh1t load more money on amendments to BS7671 publications.

 

[ericmark]

There are a few oddities
624Y Twin & Earth PVC Cable BS6004 A05VVH4-U is listed as:-

Core identification: Single core (blue or brown), 2 core (blue & brown), 3 core (black, brown & grey)

How one can have twin and earth with a single core I don't know? And I found the old red, yellow, blue colours confusing as an apprentice as I thought it would have been three phase.

The same applies to the yellow attic cable used on building sites. I have never seen anyone sleeve the blue core brown as it not neutral but line there is no neutral on a split phase 110v system. So why make cable with a blue core?

So maybe instead of twin and earth we should use sheathed flat cable with protective conductor however it is a bit of a mouth full so maybe call it twin & earth for short?

 

[holmslaw]

..

 

[ban-all-sheds]

The same applies to the yellow attic cable used on building sites. I have never seen anyone sleeve the blue core brown as it not neutral but line there is no neutral on a split phase 110v system. So why make cable with a blue core?

Because it's just flex.

 

[bernardgreen]

Yes T&E should be banned, in fact I've never understood how a cable with no method of clamping or glanding became acceptable in the first place

My question was should the word "earth" be removed from the description. There is no need to ban the type of cable as it is adequate and can be safely installed in domestic installations.

Metallic sheathed cables would only be safe to install if the necessary over current and earth leakage protection was in place.

The more complex mechanical jointing of the CPC ( the sheath ) compared to a simple wire in a screw terminal may result in more open circuited CPC and hence more hazards.

When I removed the copper sheathed sub mains to the metal consumer units in my cottage I found the glands into the consumer units were fully tightened ( I could not undo one ) yet they were still loose in the hole of the consumer unit. There was NO CPC continuity from sheath to box and hence no effective CPC in the cottage. Had the submains been twin and CPC then the chances are there would have been CPC continuity.

Untitled

• bernardgreen
• 14 Aug 2011
• 2

 

[ban-all-sheds]

Yes T&E should be banned, in fact I've never understood how a cable with no method of clamping or glanding became acceptable in the first place.

The only general wiring cables allowed should have continuous earth sheaths and a method of clamping or glanding.

We could then do away with the nonsense safe zones and rcd's that may or may not work.

Excellent Idea, and I think you should henceforth dedicate yourself 100% to making it happen.

Give it your full and undivided attention - do nothing else from morning to night except lobby politicians and regulatory bodies, and advance your career and influence to the point where you can become a member of standards committees and work on it from the inside too.

When accomplished you can come back here and tell us of your achievements, but until then don't allow yourself to be distracted - we'll be quite happy to follow your progress from afar.

 

[holmslaw]

..

 

[SimonH2]

Yes T&E should be banned, in fact I've never understood how a cable with no method of clamping or glanding became acceptable in the first place.

Sorry ?

Firstly, how can it be the cable's fault if someone hasn't done clamping and glanding methods for it ? Do you apply the same complaint to all round cables that aren't SWA ? Presumably you don't use any power tools at all, ever ?

Secondly, I think you are actually mistaken that there is no clamping or glanding method method available for flat oval cables. OK, I'm not actually aware of anything being sold here in the UK, but they both exist in the US where they use essentially the same type of cable (generally referred to as Romex I believe).

 

[Paul_C]

they both exist in the US where they use essentially the same type of cable (generally referred to as Romex I believe).

Or NM type cable "officially," for Non-Metallic sheathed. Metal outlet boxes designed for use with NM cable have clamps at the entry points to secure the cable.

 

[holmslaw]

..

 

[securespark]

Very recently a german? company have manufactured glands with oblong inserts for T&E

Not recently!

I've fitted these glands on a job in 1996...

 

[holmslaw]

..

 

[ricicle]

Why would you want to gland a properly installed t+e ? Are they subject to strain - if so they are incorrectly installed.

 

[ban-all-sheds]

Don't feed the troll.