Adding lights to circuit with no CPCs

[harrymonkfish]

Hi there.

I have been asked to add some downlights to a lighting circuit with no cpcs.

The circuit is rcd protected and he wants elv lights.

Can i just add them because they are elv or do the same rules apply as for lv?

any suggestions greatly appreciated.

harry

 

[Spudnik]

All cables must have a cpc present & connected, so it would be difficult to add or alter a circuit that doesnt have one.

You could always spur of the RFC if do-able.

 

[pushrod]

class 2 (double insulated) and class 3 (selv) does not require an earth.

 

[Spudnik]

class 2 (double insulated) and class 3 (selv) does not require an earth.

Indeed, but the cable does.

 

[supasparxs]

And yiou need to allow for future developement.
The householder may sell the house and the new owner may not want class 2 or class 3 lighting, so the circuit needs the CPC

Richard

 

[electricAl]

Indeed, but the cable does.

Haha! - not on the secondary side

In Pushrods defence, i wonder if he`s envisioning the situation to be simply taking the switched live, from the original fitting, straight to the tranny. In fact, theoretically its conceivable that it could be done without really disturbing any of the original wiring - & purely adding a Safety Isolated sub-cct (i assume Harry left the S off the ELV by accident)

Not seriously suggesting he should do it, but must admit i`m visualising how the conversation would go with Ray or Steve on the techline

I guess you don`t have to ring em to often Mr S - they call you

 

[roukel01]

reg 411.3.1.1

A CPC shall be run to and terminated at each point in wiring and at each accessory

 

[Spudnik]

reg 411.3.1.1

A CPC shall be run to and terminated at each point in wiring and at each accessory

I rest my case.....

 

[harrymonkfish]

Spur off the ring it is then.

Thanks

the guy has also asked for mini downlights? anyone heard of these? smaller than GU10.

 

[roukel01]

yeah, usually have g9 lamps in. In my opinion. Crap.

 

[Davey101]

reg 411.3.1.1

A CPC shall be run to and terminated at each point in wiring and at each accessory

I saw this reg the other day, but didnt give it much thought, as I presumed it related to a conventional 3 plate system.
Does this mean that I cant run a 2 core to a double insulated (or more likely a 12volt) light fitting, but instead have to run a 3 core, which will be conected to nothing?
The only benefit I can see for this is for testing/fault finding.
Not arguing with anyone, just cant see the point, unless its for future use of course.

 

[Spudnik]

If the cable was damaged, how would the fault clear to earth?

 

[Davey101]

Through the neutral?
Not meaning to sound stupid or argumentative, its something that I have given thought to in the past, but didnt realise that there was a particular reg for it.
Are we saying that you cant use any 2 core cable for anything above selv?
Going off on a bit of a tangent here, and not really helping the OP

Also, this may be a little random, but I vaguely remember this question coming up at a course somewhere(it may have been on my 17th edition course). The answer given, IIRC, was that if you had plastic boxes i.e not metal knockout boxes and plastic light fittings, then you could get away with not having a cpc on the lighting circuit. In my experience though lecturers aren't always right......

 

[Phil Mumford]

I have an old chestnut for you......what if the light fittings are not accessible simultaneously with an exposed conductive part?

I think I will manufacture and market 1.5 kVA isolating transformers for old lighting circuits

 

[electricAl]

reg 411.3.1.1

A CPC shall be run to and terminated at each point in wiring and at each accessory

Indeed it should - if ADS is used as the means of providing basic & fault protecction

But, of course, that isnt the only form of `Protective Measure` we can utilise - else we`d be a bit restricted wouldn`t we

Others we can (& do) utilise are: double or re-inforced insulation; electrical seperation; and the use of ELV by SELV (or PELV come to think of it)

Come on fellas, how the hell would SELV be of any use if we had to supply a cpc

Kinda defeat the object wouldn`t it

I rest my case.....

...& me

sorry J, couldn`t resist it