Why "No RCD protection on lighting circuit"?

[bazme]

Hi all – can any body please help?

Had Building Control organised electrical inspection recently on an extension I built.

It came back with “no RCD protection on lighting circuit” and earth cables in switches not connected (I had heat shrunk sleeving over the ends intending to get choc blocks – then forgot).

The inspection passed the other wiring (sockets, cooker, extractor hood) all of which go back to the same Wylex CU.

The lighting circuit is based on twin and earth 1.5mm cable with plastic switch/back boxes. I have had bulbs fail and the MCB trips.

I have now terminated earth cables in single switches with choc blocks and in 2/3 gang switches I have connected the earth cables via choc block.

Does RCD protection require all earthing to be connected? Would floating earth leads in switches cause “no RCD protection on lighting circuit”?

If not - any other suggestions?

Many thanks

 

[JohnW2]

It came back with “no RCD protection on lighting circuit” ...

That presumably is just a statement of fact - i.e. that the lighting circuit is not protected by an RCD in your CU. There is no regulatory requirement for a lighting circuit to be RCD-protected, per se, but if there is any new wiring buried <50mm deep in walls, that would invoke a requirement for RCD protection.

and earth cables in switches not connected (I had heat shrunk sleeving over the ends intending to get choc blocks – then forgot). ... plastic switch/back boxes. I have now terminated earth cables in single switches with choc blocks and in 3 gang switches I have connected the earth cables via choc block.

I can but presume that they were unhappy with the (insulated) earth wires 'flopping about', in which case terminating them in bits of chock block (if there is no earth terminal on the switch) should keep them happy.

Does RCD protection require all earthing to be connected? Would floating earth leads in switches cause “no RCD protection on lighting circuit”?

No - as above, they are two separate issues. If you have new buried cables, then something will have to be done at the CU to remedy that. One solution, if an easier one does not present itself, would be to change the lighting circuit MCB to an RCBO.

Kind Regards, John

 

[EFLImpudence]

The lighting circuit is based on twin and earth 1.5mm cable with plastic switch/back boxes. I have had bulbs fail and the MCB trips.

That's what they do sometimes.

I have now terminated earth cables in single switches with choc blocks and in 2/3 gang switches I have connected the earth cables via choc block.

Is everything plastic - not metal back box or metal switch?

Does RCD protection require all earthing to be connected?

Not RCD - but of course, although you cannot connect to plastic.

Would floating earth leads in switches cause “no RCD protection on lighting circuit”?

No.

An RCD is a protection device which must be fitted to NEW wiring under certain conditions and sockets.

It is not required on a lighting circuit just for the sake of it.

 

[sparkwright]

As indicated earlier, if some of the lighting wiring is less than 50 mm from the depth of the wall surface, or is in a bathroom, then that wiring at least needs to be protected by an RCD.

The simplest way to achieve this is replace the MCB covering the circuit in question for an RCBO.

AS INDEED JOHN HAS TOLD US.

 

[JohnW2]

As indicated earlier, if some of the lighting wiring is less than 50 mm from the depth of the wall surface, or is in a bathroom, then that wiring at least needs to be protected by an RCD.

I know that some probably disagree, but I would say that's only the case if any of the new wiring is buried <50mm or if work relates to a bathroom. I don't think that there is a requirement to provide RCD protection for pre-existing wiring that comes into those categories, is there?

The simplest way to achieve this is replace the MCB covering the circuit in question for an RCBO. AS INDEED JOHN HAS TOLD US.

Indeed

Kind Regards, John

 

[sparkwright]

Can anyone remind me if new outside lights need to be RCD protected now?

My gut reaction is no.

 

[bazme]

Very many thanks for replies.

The lighting wiring is not <50mm from any surface and the inspector never checked anyway. And why pick on the lighting circuit? - the socket wiring goes through the same partition and in places is 12.mm from a surface (in recommended zones).

All switches and sockets, back boxes are plastic. No metal faceplates.

He has not just made observations - they are failure points. Everything is very easy to fix except the RCD protection on the lighting circuit.

From your suggestions it appears that a lighting circuit connected to a CU with RCD protection does not guarantee that the lighting circuit is RCD protected? Are my other circuits RCD protected?

If an RCBO is available for my CU (the breakers are type NSB) then I would get gladly get the MCB replaced.

 

[EFLImpudence]

Can anyone remind me if new outside lights need to be RCD protected now?

My gut reaction is no.

Appliances never require RCD protection.
It is the cable which may require it.

 

[JohnW2]

Can anyone remind me if new outside lights need to be RCD protected now? My gut reaction is no.

Not that I am aware of, sensible though it might be.

Kind Regards, John

 

[EFLImpudence]

He has not just made observations - they are failure points. Everything is very easy to fix except the RCD protection on the lighting circuit.

That is easy to fix.

From your suggestions it appears that a lighting circuit connected to a CU with RCD protection does not guarantee that the lighting circuit is RCD protected? Are my other circuits RCD protected?

The circuits marked with green on the CU are protected.

If an RCBO is available for my CU (the breakers are type NSB) then I would get gladly get the MCB replaced.

There you go.

 

[JohnW2]

Appliances never require RCD protection. ... It is the cable which may require it.

I'm not so sure about that. For a long time there has been a requirement for RCD protection of a socket likely to supply an 'outdoor appliance', even when the same circuit, with the same cable would not have required RCD protection if there were no socket likely to be used for outdoor equipment. Similarly with the requirements we now have for RCD protection of any circuit supplying a bathroom - again, it's not really the cable that is being protected, but, rather, whatever the cable is connected to.

Kind Regards, John

 

[flameport]

The lighting wiring is not <50mm from any surface

Not even where the cables drop down to the switches?

TAnd why pick on the lighting circuit? - the socket wiring goes through the same partition and in places is 12.mm from a surface (in recommended zones).

The sockets have RCD protection. The lights do not.
The RCD is the double width device in the centre of the consumer unit. It covers all of the circuits to the left of it.
The circuits at the right are NOT covered by the RCD.

The issue with the earths was they they were not connected together - not the fact that they didn't have a terminal on the end.

What is circuit 8 and why does it not have overcurrent protection?

 

[sparkwright]

Very many thanks for replies.

The lighting wiring is not <50mm from any surface and the inspector never checked anyway. And why pick on the lighting circuit? - the socket wiring goes through the same partition and in places is 12.mm from a surface (in recommended zones).

All switches and sockets, back boxes are plastic. No metal faceplates.

He has not just made observations - they are failure points. Everything is very easy to fix except the RCD protection on the lighting circuit.

From your suggestions it appears that a lighting circuit connected to a CU with RCD protection does not guarantee that the lighting circuit is RCD protected? Are my other circuits RCD protected?

If an RCBO is available for my CU (the breakers are type NSB) then I would get gladly get the MCB replaced.

In your picture, all the circuits to the left of that RCD (RCCB) are protected by RCD.

That's why the inspector wasn't concerned with your sockets.

How are your lighting cables run? I suspect even in stud walls, the wiring may be considered less than 50 mm from the wall surface.

You haven't mentioned if any of this lighting wiring enters a bathroom.

Answer this.

If the new wiring is more than 50 mm from the wall surface and doesn't enter a bathroom, then it would seem you don't need RCD protection for the new lighting.

 

[JohnW2]

The lighting wiring is not <50mm from any surface and the inspector never checked anyway. And why pick on the lighting circuit? - the socket wiring goes through the same partition and in places is 12.mm from a surface (in recommended zones).

He's only 'picked on' the circuit because it is one of the few which doesn't have RCD protection. As far as I can make out from your photo, the sockets circuit is RCD protected.

However, I'm still not sure why he thinks that RCD protection is required for the lighting circuit. If it's really true that none of the new wiring is buried <50mm deep (how have you got cables to light switches?), and if no work has been done in a bathroom supplied by that lighting circuit, then I can't really see how a regulatory need for RCD protection arises.

From your suggestions it appears that a lighting circuit connected to a CU with RCD protection does not guarantee that the lighting circuit is RCD protected? Are my other circuits RCD protected?

Most of your circuits are RCD protected. The three right-most ones, with a red bar under them, are not RCD-protected.

If an RCBO is available for my CU (the breakers are type NSB) then I would get gladly get the MCB replaced.

An RCBO will be available, and that's the simplest solution, even if I'm not yet certain that there truely is a requirement for RCD protection of the lighting circuit.

Kind Regards, John

 

[JohnW2]

The issue with the earths was they they were not connected together - not the fact that they didn't have a terminal on the end.

Ah, good point!

Kind Regards, John