Adding a light to a circuit with no earth

[robo83]

Got to quote a job where the existing circuit does not have an earth.

It's swapping a pendant for 3 Downlights.

The board was changed about 2 yrs ago and has labels indicating no CPC on lighting.

All Fascias are plastic. Where do I stand Regards this, I understand you can accept no CPC on lighting with Fascias but not sure about modifying the circuit.

 

[Ian1981]

The downlights your installing will need to be class 2 rated of course.
Is it in a bathroom?

 

[Spoon]

How hard would it be to add a 4mm earth?

 

[robo83]

It's in a kitchen.

 

[Wilko]

My thought is to look in CU and see if cct starts with cpc in earth bar, then look at the cable inco to pendant, it might just be cut back ? (optimistic me)

 

[Octopus]

Class 2 downlights and a decent note on the cert.

 

[Midwest]

Can't see that you can. If you are adding new wiring, reg 411.3.1.1 'A cpc shall be run to & terminated at each point in wiring & at each accessory except a lamp holder having no exposed conductive parts.....'.

If it was the case of just replacing luminaires, Class 2 and note etc.

 

[Ian1981]

Can't see that you can. If you are adding new wiring, reg 411.3.1.1 'A cpc shall be run to & terminated at each point in wiring & at each accessory except a lamp holder having no exposed conductive parts.....'.

If it was the case of just replacing luminaires, Class 2 and note etc.

A cpc will be ran in by the op I would imagine if altering installing new wiring to luminaries.
Granted it may not do anything but a class 2 luminar will have no exposed conductive parts so the wiring will be no more dangerous than previous with a relivant note on a MWC

 

[Midwest]

A cpc will be ran in by the op I would imagine if altering installing new wiring to luminaries.

That's the issue, the way I read the OP's post?

 

[Ian1981]

That's the issue, the way I read the OP's post?

Yeah no cpc to existing circuit db is labelled as such.
However if installing class 2 there is no exposed conductive parts so a fault to the enclosure cannot give a person an electric shock by touching it.
Wiring hopefully covered for overload and short circuit protection by a adequate protective device.
I don't see a problem with it as long as it's clearly identified at the db which it is.
Also note the MWC

Obviously class 1 luminaries are a no no unless a cpc is installed from the db perhaps

 

[Andy78]

A cpc will be ran in by the op I would imagine if altering installing new wiring to luminaries.
Granted it may not do anything but a class 2 luminar will have no exposed conductive parts so the wiring will be no more dangerous than previous with a relivant note on a MWC

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.

 

[Spoon]

I don't think he is extending the circuit. Just swapping lights.

It's swapping a pendant for 3 Downlights.

 

[Midwest]

Yeah no cpc to existing circuit db is labelled as such.
However if installing class 2 there is no exposed conductive parts so a fault to the enclosure cannot give a person an electric shock by touching it.
Wiring hopefully covered for overload and short circuit protection by a adequate protective device.
I don't see a problem with it as long as it's clearly identified at the db which it is.
Also note the MWC

Obviously class 1 luminaries are a no no unless a cpc is installed from the db perhaps

That's not the way I read the reg; new wiring, cpc to each terminated point.

 

[Karin]

1 Pendant to 3 downlights.. so +2 points extension to the circuit?

 

[Spoon]

1 Pendant to 3 downlights.. so +2 points extension to the circuit?

Balls....
I read it as 1 pendant to another fitting with 3 lights on... My fault....

I'm sure the OP will clarify all this...

 

[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

 

[Midwest]

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

Just a thought Is that a double negative thing?

 

[Midwest]

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

That's not a reason, not to have them. Anything that makes things which are unclear more clear, must be grasped,

 

[Wilko]

My thought is any new cable must have a cpc, and the cpc must be tested and confirmed for connectivity to the MET. And these are new cables to the new downlight positions...

 

[Andy78]

That's not a reason, not to have them. Anything that makes things which are unclear more clear, must be grasped,

They certainly don't not make things less unclear than they wouldn't have not been if they weren't there at all.

 

[robo83]

Thanks for all the replies.

 

[Midwest]

They certainly don't not make things less unclear than they wouldn't have not been if they weren't there at all.

Arrgh you missed the point;

 

[Midwest]

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

Any more technical points on the above?

 

[Risteard]

That's not a reason, not to have them. Anything that makes things which are unclear more clear, must be grasped,

There's no reason to prescribe a label for a prohibited arrangement though.