Adding a light to a circuit with no earth

[Karin]

i think we got all outcomes covered anyways!

 

[Ian1981]

So let's say the circuit has a cpc
If class 2 lights are fitted what is the cpc actually doing?
Yes it's required to be terminated at each point and accessory but in the case of class 2 fittings it function is not required.
By that I don't mean you'd just snip the cpc off by the way.

Would you then not change a db if all lights are class 2 and the switches and no cpc to circuit?
Suitably labelled as required

The work covered ,the wiring is no more dangerous than the previous way it was.

 

[Ian1981]

The definition of a cpc is a conductor that is connected to the MET.
So I would read 411.3.1.1 as each point requires a conductor that is connected to earth.
612.2.1 requires that continuity of protective conductors is carried out during testing.
132.16 requires that all existing equipment and arrangements are suitable for safe alteration before the work is carried out.

I would personally not extend a circuit with no cpc.

A definition of a cpc also says connecting exposed conductive parts of equipment to the MET of which there would be no exposed parts of class 2 equipment.
Continuity of cpc would be N/A as there is no cpc to the circuit.
The wiring installed to the altered wiring would contain a cpc, granted it's doing nothing but again it's being installed in the altered works.
If someone in the future wants to fit metallic fittings then the db is labelled to advise against it.

Just my view on it.
I appreciate your view so not starting an argument Andy.

 

[Risteard]

the wiring will be no more dangerous than previous with a relivant note on a MWC

It mightn't be more dangerous, but it would still fail to meet the minimum safety standard for electrical installation work, i.e. BS7671.

 

[Risteard]

I would personally not extend a circuit with no cpc.

You could of course connect a cpc to that of another circuit. However if it is not mechanically protected then the minimum cross-sectional area of this cpc will be 4mm^2.

 

[Ian1981]

It mightn't be more dangerous, but it would still fail to meet the minimum safety standard for electrical installation work, i.e. BS7671.

Why? It's changing a pendant to 3 down lights.
Class 2 fittings hopefully.
Same as if you change a db and reconnect the lights.
If all class 2 you wouldn't rip the place apart installing a cpc unless agreed with customer

 

[Risteard]

Why? It's changing a pendant to 3 down lights.

Why would it fail to meet BS7671? Quite simply because it wouldn't comply with it.

 

[Ian1981]

Why would it fail to meet BS7671? Quite simply because it wouldn't comply with it.

By that logic a lighting circuit containing no cpc must not be re-energised when renewing a consumer unit even with class 2 fittings fitted and suitably labelled which is allowed by bs 7671

A cpc is required to connect exposed conductive parts to the MET so if a fault of negligible impedance between live and earth happens current will flow and disconnect the protective device,but tell me what exposed parts are there on a class 2 light?

 

[Midwest]

But the point is Ian, if you are installing new wiring, i.e. alteration or addition, then whatever you do must comply with current edition BS 7671.

If you are installing a new CU and connecting a lighting circuit without a cpc, you are not adding to etc, and 'conditions' apply, otherwise the circuit should not be connected (most guidance I've read, also recommends advising customer to rewire said circuit).

I have not read, or been informed by others, that it is compliance with BS 7671, to add new wiring to an existing circuit without a cpc.

 

[Risteard]

By that logic a lighting circuit containing no cpc must not be re-energised when renewing a consumer unit even with class 2 fittings fitted and suitably labelled which is allowed by bs 7671

Firstly replacing a distribution board is quite different as you are not altering the existing circuit (leaving aside the protective device for now). So you are only required to verify your installation work (namely the replacement distribution board) - so you would ensure that the protective devices will operate in the time required. It doesn't mean that you are taking responsibility for installation methods; core colours etc.

Secondly, you state "with Class II fittings fitted and suitably labelled which is allowed bs BS7671". Can you quote where BS7671 suggests that this is acceptable, or prescribes any label for this eventuality? I can assure you that it is not contained within BS7671.

 

[Ian1981]

Available from Niceic direct
Bs 7671 does not go into long explanations of rules and regulations.
It's a set of regulations hence why we have guides and guidance notes to break the information down in to chunks

Firstly replacing a distribution board is quite different as you are not altering the existing circuit (leaving aside the protective device for now). So you are only required to verify your installation work (namely the replacement distribution board) - so you would ensure that the protective devices will operate in the time required. It doesn't mean that you are taking responsibility for installation methods; core colours etc.

Secondly, you state "with Class II fittings fitted and suitably labelled which is allowed bs BS7671". Can you quote where BS7671 suggests that this is acceptable, or prescribes any label for this eventuality? I can assure you that it is not contained within BS7671.

 

[Midwest]

Whilst researching this topic, I found reg 412.2.3.2, which I'll let you chaps read and explain, cos my heads hurting now.

On this point, would running a cable from a 12v dc transformer, to a remote luminaire require a cpc?

 

[Risteard]

I am aware that such labels are for sale - my point is that they have no basis within BS7671.

 

[Ian1981]

i would say not every label available is written in the realm of bs 7671 on display as it where

 

[Ian1981]

Whilst researching this topic, I found reg 412.2.3.2, which I'll let you chaps read and explain, cos my heads hurting now.

On this point, would running a cable from a 12v dc transformer, to a remote luminaire require a cpc?

Well I'd say if it's selv then the cpc is required to be not connected to the primary side of the source