Earth funnies and phantom voltages on lighting circuit

[Jurassicspark]

Most other light fittings have earth terminals, even if they are Class II.

Which can sometimes be beneficial if the manufacturer may not feel confident that the item will remain as a class 2.

 

[JohnW2]

Most other light fittings have earth terminals, even if they are Class II.

I suppose it depends upon what you mean by a 'light fitting', but I'm not at all sure about that. For example, as you go on to acknowledge, an increasing number of 'throwaway' LED lights appear to have no terminals all, just a bit of 2-core flex dangling out of them so ....

Anything that doesn't should have space to tuck in a connector for the spare cpc, or else the fitting will have a lead attached which will go to a junction box and the cpcs will terminate in there.

"A space to tuck in a connector for the spare CPC" presumably would not have qualified as the terminal required by 14th edition and, although, as you say, the lead dangling out of others will go to a junction box, where a terminal can be provided for the CPC, I would have thought that the light ('fitting') itself would have qualified as a 'lighting point' which would have required an 'earth terminal' under 14th, wouldn't it?

 

[JohnW2]

Which can sometimes be beneficial if the manufacturer may not feel confident that the item will remain as a class 2.

Only if the 'earth terminal' is actually connected to something - rather than just being a 'floating parking space' as it often is.

Edit: on reflection, you probably didn't literally mean ".... the item will remain as Class 2" (which presumably it would) but, rather, "... the Class Ii item will not ever be replaced by a Class I one" - in which case I agree with you that the 'availability' of a CPC is desirable.

 

[securespark]

Are you sure about the Class II ones.


Surely having a CPC in a Class II item is not desirable.

Purely for continuity purposes, isolated from the fitting.

As 412.2.3.2 states. Run to and terminated at each point in wiring and at each accessory.

 

[EFLImpudence]

Purely for continuity purposes, isolated from the fitting

As the regulation states, it is purely in case it is needed in the future.
A daft reason for a regulation in my opinion.

As 412.2.3.2 states. Run to and terminated at each point in wiring and at each accessory.

Ok...

Well, all ceiling roses, boxes, pattresses, junction boxes etc have earth terminals. Most other light fittings have earth terminals, even if they are Class II.

... but Class II fittings will not have an earth terminal.

 

[securespark]

I suppose it depends upon what you mean by a 'light fitting', but I'm not at all sure about that. For example, as you go on to acknowledge, an increasing number of 'throwaway' LED lights appear to have no terminals all, just a bit of 2-core flex dangling out of them so ....

"A space to tuck in a connector for the spare CPC" presumably would not have qualified as the terminal required by 14th edition and, although, as you say, the lead dangling out of others will go to a junction box, where a terminal can be provided for the CPC, I would have thought that the light ('fitting') itself would have qualified as a 'lighting point' which would have required an 'earth terminal' under 14th, wouldn't it?

I didn't realise we were suddenly comparing modern fittings with a 60 year old book of regulations.

You said:

Today, there is a requirement to run a CPC to every point/accessory, but no requirement of which I'm aware to 'connect' it to anything - and nor do many present day 'lighting points' have an 'earthing terminal', do they?

As above. 412.2.3.2.

 

[JohnW2]

I didn't realise we were suddenly comparing modern fittings with a 60 year old book of regulations.

Well, you wrote of light fittings, ceiling roses, boxes, pattresses, junction boxes etc. and "anything which didn't have an earth terminal" in the present tense, and also mentioned "Class II" (did that concept {or 'ceiling roses'} exist 60 years ago?) so, yes, I thought you were essentially thinking of 'modern fittings'.

You said: .... As above. 412.2.3.2.

Yes, but as I said, 412.2.3.2 requires the CPC to be 'terminated' at every point and accessory in a circuit, but that does not (and, in many cases, cannot) necessarily mean that the CPC is 'connected to' anything other than the terminal, does it?

 

[securespark]

As the regulation states, it is purely in case it is needed in the future.
A daft reason for a regulation in my opinion.

Maybe. But a reg we should keep to.

... but Class II fittings will not have an earth terminal.

What? Like the Aurora AU150? Double Insulated with earth terminal to provide continuity......

 

[JohnW2]

What? Like the Aurora AU150? Double Insulated with earth terminal to provide continuity......

What does "earth terminal to provide continuity" mean? Continuity between what and what?

 

[securespark]

Well, you wrote of light fittings, ceiling roses, boxes, pattresses, junction boxes etc. and "anything which didn't have an earth terminal" in the present tense, and also mentioned "Class II" (did that concept {or 'ceiling roses'} exist 60 years ago?) so, yes, I thought you were essentially thinking of 'modern fittings'.

Of course Class II, double insulation and ceiling roses existed 60 years ago.
Both are older.

Yes, but as I said, 412.2.3.2 requires the CPC to be 'terminated' at every point and accessory in a circuit, but that does not (and, in many cases, cannot) necessarily mean that the CPC is 'connected to' anything other than the terminal, does it?

I'm not quite sure what you are trying to say here.

In a Class I luminaire, the terminal will be connected to the metalwork. In double insulated fittings or accessories, the terminal will just be there for continuity purposes and not connected to anything.

 

[SUNRAY]

...In a Class I luminaire, the terminal will be connected to the metalwork. In double...

If it has any metalwork

 

[JohnW2]

Of course Class II, double insulation and ceiling roses existed 60 years ago. Both are older.

Thanks - but as for "of course", I obviously did not know (at least about the 'Class II') which is why I asked the question
[ I suppose I actually did know that we have had 'ceiling roses' since the year dot, and was really thinking about 'ones as we know today' - which probably rather confused what I wrote! ]

I'm not quite sure what you are trying to say here. .... In a Class I luminaire, the terminal will be connected to the metalwork...

If there is any. Many/most of the Class II items I have do not have any metalwork (at least, not 'touchable metalwork') to which on could connect anything!

. In double insulated fittings or accessories, the terminal will just be there for continuity purposes and not connected to anything.

I suppose I've just been questioning the meaning of your choice of words. You again write "for continuity purposes" which leads me to again ask "continuity between what" and what? I presume the underlying concept you're trying to get across is that the CPC is there "in case needed in the future" but I would be more certain of that if you had written something like that, rather than repeatedly talking about 'continuity'

 

[SUNRAY]

...I suppose I've just been questioning the meaning of your choice of words. You again write "for continuity purposes" which leads me to again ask "continuity between what" and what? I presume the underlying concept you're trying to get across is that the CPC is there "in case needed in the future" but I would be more certain of that if you had written something like that, rather than repeatedly talking about 'continuity'

The classic situation is a lighting circuit with loop and CPC terminal at the rose providing continuity to the switch and of course subsequent roses and switches

 

[securespark]

If there is any. Many/most of the Class II items I have do not have any metalwork (at least, not 'touchable metalwork') to which on could connect anything!

Read what I put. I was talking there about Class I luminaires.

I suppose I've just been questioning the meaning of your choice of words. You again write "for continuity purposes" which leads me to again ask "continuity between what" and what? I presume the underlying concept you're trying to get across is that the CPC is there "in case needed in the future" but I would be more certain of that if you had written something like that, rather than repeatedly talking about 'continuity'

This is all hinging around the regulation that EFLI first quoted.

Where you have a cable in and a cable out, an earth terminal is needed to ensure earth continuity round the circuit to comply with the reg.

 

[JohnW2]

The classic situation is a lighting circuit with loop and CPC terminal at the rose providing continuity to the switch and of course subsequent roses and switches

Ah, I see. That is why we have been writing somewhat 'at cross-purposes'!

Yes, that is, indeed, a matter of 'providing continuity', but that's totally different from 412.2.3.2 (which is what I thought we were discussing) which requires a CPC to be 'run' to each point/accessory in a circuit supplying one or more Class II items "to take account of the replacement by the user of Class II equipment by Class I equipment - which doesn't necessarily involve any 'continuity' considerations.