2 core cable..

[Crosswire]

If you for instance were to run a cable with no joins, directly from a CU to to a double insulated item of equipment, how many points in the wiring requiring a CPC to be connected would there be?
If no accessories are used in the circuit (remembering that an item of current using equipment is not considered to be an accessory) where would you connect a CPC?

Can't think of anywhere that I could connect the cpc to, other than a wago or the terminal of the back box ( if applicable). In the fan itself I would sleeve the cpc and terminate it in a floating wago, or crimp, or screw type terminal block.

Of course it is impossible to earth a piece of plastic, but if the Regs say I must run a cpc to it, then I must comply, whether it makes sense or not......

 

[Les Macaulay]

spinlondon is talking sense. To avoid bad job relations with the tester, change the cable to 3core but make sure you insulate the end of the cpc after sleeving it, or better still over-sleeve it. You are perfectly correct installing the 2core, but the tester is trying to be pedantic and perhaps over-zealous. Refer to your supervisor discretely if that's possible. The label is a good idea, i.e. class ii equipment - no cpc required. There will be no where to connect a cpc any how except in the termination box of the local maintenance switch.
Cheers
Les

 

[Deleted member 26818]

Regulation 412.2.4 wouldn't allow the termination of the CPC within the fan into a wago, crimp or terminal block, unless specifically provided by the manufacturer of the fan.

 

[Engineer54]

If you take this BS7871 regulation literary, that a CPC should always be taken to any class11 accessory, Then you have to ask ''Why'' do all the manufacturers of class11 equipment that supply a factory fitted lead/cable only ever provide that lead/cable with a 2 cores?? lol!!

 

[kingeri]

Using 3 core for class II items such as downlights and fans is a bad idea in my view, it's why we so often see CPCs just cut off and not terminated - cos there's nowhere to terminate it to.

 

[dim_bulb]

spinlondon is just too cool for school

on a realistic point this two core cable where would you get it from? left over under cupboard light cable?

do you think there was a slight debate in the 60s regarding 2 core cable because at the time the fashion was wooden backs,

 

[MDJ]

Ive got some 2 core flex on my van, use it to extend pendants in houses with high ceilings, I suppose we could run it to a table lamp in a restaurant through some soil with plants in it like they do in spain.

 

[ben sparkz]

How can the tester get an r1+r2 reading? its good practise to continue the cpc even though the the item is double insulated. I was taught that you need an cpc to make it easier to test and also to allow for future references i.e change for a metal item at a later date, also live and neutral conductors needs to be the same size. (just in case single and earth was used)

 

[Engineer54]

(just in case single and earth was used)​

​

Pardon????

 

[Crosswire]

Regulation 412.2.4 wouldn't allow the termination of the CPC within the fan into a wago, crimp or terminal block, unless specifically provided by the manufacturer of the fan.

Can you be more specific? In my Regs 412.2.4 is a subject heading "Wiring systems"

 

[Crosswire]

Also, surely terminating correctly is preferable to cutting it off? Why would it be prohibited?

 

[Deleted member 26818]

Sorry should be 412.2.2.4.

 

[jumpin jax]

Its a bit ambiguous really, i read it as the cpc must not be connected to an ECP unless catered for, not you can't terminate in a floating wago, as long as it is marked as a cpc

 

[Deleted member 26818]

If you were to park the CPC in a 'wago' would the 'wago' not then become an ECP, one that was not catered for?
Or in other words not specifically provisioned for in the specifcation for the equipment concerned.

 

[jumpin jax]

Technically yes, but that would mean we would have to put either a maintenance free enclosure to terminate the cpc in and then 2(3) core flex to the fan or an ip44 enclosure near to the fan then flex to the fan, we wouldnt get any work done:frown2:

Out of interest, how do you terminate your domestic fan feeds?

 

[Deleted member 26818]

It's not something that I've come across in domestic installations to that extent, as the fans I use are either SELV or 230V wired with 3core&E.
However, with a bell transformer for instance, I would normally just take 2 cores to the transformer.
Where I've installed class II equipment in commercial or industrial installations, I generally take a CPC to a JB or enclosure near to the equipment, park it, then run 2core to the equipment.
However, there have been times when I've not had that option, and following instructions, have cut the CPC out of T&E or 3core flex then terminated in the class II equipment.

In many instances running a CPC to and parking it in the enclosure of an item of class II equipment is not going to make a blind bit of difference.
The likelyhood of the CPC becoming loose and shorting against a live conductor is just the same for Class II equipment as it is for Class I equipment.
However if that CPC were to come into contact with an exposed-conductive-part it could introduce a difference in potential.
Something that may not be desired if the equipment is installed in certain locations.
It could even allow fault currents from a fault elsewhere in the installation to enter a location where such currents could be present a danger.

 

[Geoffsd]

If you were to park the CPC in a 'wago' would the 'wago' not then become an ECP?

If the wago were 'just there' without the cpc in it, would it be an ECP and require earthing?

Or - If the wago was being used to connect the Line conductors would it be an ECP?

 

[Crosswire]

412.2.3.2 "Except where Regulation 412.1.3 applies, a circuit supplying one or more items of Class II equipment shall have a circuit protective conductor run to and terminated at each point in wiring and at each accessory."

412.2.2.4 "No conductive part enclosed in the enclosure shall be connected to a protective conductor.......Inside the enclosure, any such conductor and their terminals shall be insulated as though they were live parts, and the terminals shall be marked as protective conductor terminals

No exposed-conductive part or intermediate part shall be connected to any protective conductor unless specific provision for this is made in the specification for the equipment concerned"


The first Reg says I have to run a cpc to the fan. Fair enough. Can't see how the second Reg prevents me from terminating the cpc in a wago or terminal block.

Am I missing something?


​

 

[Geoffsd]

.Nope.

 

[Stroppy]

As a connector block or wago is not an exposed conductive part, or part of the equipment at all (merely living in a cavity inside it), then this doesn't count as connecting a CPC to something in a Class2 device.

 

[Engineer54]

What a pointless Thread!!

 

[Geoffsd]

It's never pointless enlightening those who don't know or are mistaken.

 

[Octopus]

It's never pointless enlightening those who don't know or are mistaken.

So can you summarise in plain English the outcome of this thread?

 

[Geoffsd]

So can you summarise in plain English the outcome of this thread?

Yes.

When supplying an item of double insulated equipment, (in this case an extract fan). Is it acceptable to use a two core cable i.e. no cpc?

No. Two core cable is not acceptable (412.2.3.2) but some will not accept this and keep arguing.

 

[Octopus]

Yes.



No. Two core cable is not acceptable (412.2.3.2) but some will not accept this and keep arguing.

Brilliant. A nice clear reg and its also good practice too!