Consumer unit and lights require adding to Rcd circuit?

[TheOriginalTableLeg]

I was talking to an electrician today about having an additonal light fitted into our living room and he said that recent changes to the electrical regulations require that all new lighting circuits need to be on an Rcd circuit.

This got me to thinking....

Does that mean only new circuits need to be added to an Rcd and existing ones which may not be are left as is?

or that a new circuit and subsequently all other similar circuits (lights for example) are required to be rewired onto an Rcd circuit?

Does this not cause some problems with the consumer unit not having enough space for additional circuits on the Rcd side?
If so, what do people do, add an extra Cu or replace with an even bigger Cu?

If a consumer unit has say for example 2x lighting circuits i.e. Upstairs and downstairs, would these both have to be on a separate Mcb on the Rcd circuit or could they connected into the same Mcb (of appropriate rating) thus saving a space in the Cu?

 

[riveralt]

I was talking to an electrician today about having an additonal light fitted into our living room and he said that recent changes to the electrical regulations require that all new lighting circuits need to be on an Rcd circuit.

But this is not a new lighting circuit it is an additional light. In your circumstances you do not need RCD if the new cable is more than 50mm from the plasterboard surface or mechanically protected et al.

I'm not 100% sure but I think that this part of BS7671 is being repealed in July and will be replaced on a more risk assessed basis.

Does that mean only new circuits need to be added to an Rcd and existing ones which may not be are left as is?

Yes but see above.

or that a new circuit and subsequently all other similar circuits (lights for example) are required to be rewired onto an Rcd circuit?

Each case will be determined on its merits as outlined above.

Does this not cause some problems with the consumer unit not having enough space for additional circuits on the Rcd side?
If so, what do people do, add an extra Cu or replace with an even bigger Cu?

If there is no space then yes.

If a consumer unit has say for example 2x lighting circuits i.e. Upstairs and downstairs, would these both have to be on a separate Mcb on the Rcd circuit or could they connected into the same Mcb (of appropriate rating) thus saving a space in the Cu?

You can of course have two or more circuits connected to one MCB. However in the circumstances you describe its not really good practice - as all your lights would go off if there was a problem.

 

[TheOriginalTableLeg]

Thanks for the reply

So to clarify, adding an additional light to an existing light ring circuit would not require a separate connection to an Rcd circuit? i.e. would be connected in the ring either by loop in or junction box?

What therefore is the difference (in terms of the electrical regs) between an additional circuit and a new one?

 

[riveralt]

Thanks for the reply

So to clarify, adding an additional light to an existing light ring circuit would not require a separate connection to an Rcd circuit? i.e. would be connected in the ring either by loop in or junction box?

It is very unlikely that you have a 'light ring circuit' - most lighting circuits are radials. So when you add a light to the circuit not create an additional circuit even so the RCD conditional check list above will apply.

What therefore is the difference (in terms of the electrical regs) between an additional circuit and a new one?

The key words are addition to a circuit.

If you add an additional circuit to the consumer unit the RCD check list outlined above apply.

 

[TheOriginalTableLeg]

Thanks again for the reply.

My mistake, I did mean Radial for the lighting.

What do you mean by 'Mechanically protected' in reference to the cable?

 

[echoes]

Generally earthed, steel conduit. Like in the pic halfway down here

 

[holmslaw]

..

 

[RF Lighting]

That's what I did in my house. (the pic is from my hallway)

 

[ricicle]

That's what I did in my house. (the pic is from my hallway)

Is your house not under the supervision of a competant person then Rob ?

 

[RF Lighting]

Not always

 

[holmslaw]

..

 

[echoes]

Generally earthed, steel conduit. Like in the pic halfway down here

Is that what you do in a house?

I'm afraid I'm slumming it with mini-trunking for my non-rcd fridge-freezer circuit.