Green and yellow wires not used as earth and missing earths.

[bernardgreen]

still don’t see the logic of supplying a cpc,

(1) a future change of equipment that does require an Earth
(2) an accidental nail or screw through the cable has a good chance of touching the Earth conductor and thus avoiding live metal projecting out of the wall / floor

 

[JohnW2]

Yes @JohnW2, but can you get class 1 wireless thermostats? I’m talking about 5 core flex running from a combi boiler to a double insulated receiver - still don’t see the logic of supplying a cpc, unless it can be swapped for a class 1 receiver?

That's rather different from what we're talking about - I though we were talking about the 'actual thermostat', not a wireless receiver, although that doesn't really change things much.

If the thermostat/transmitter is battery-operated, then it obviously ceases to be part of the electrical installation, so no regs apply (the existing cable could simply be disconnected at both ends and would become 'a bit of unused cable in a wall', subject to no regulations.

If any mains voltage (e.g. to power it) existed at the thermostat/transmitter), then the situation would remain as we have been discussing.

As for the receiver (or anything else connected to a mains supply), the potential presumably exists for it to be changed to a Class I one in the future (if one exists, or comes to exist), just as with a light fitting, doesn't it.

However, now that you're talking about it, in the case of the receiver, there is probably scope for debating whether it actually forms part of the 'electrical installation', which is all that the regulations relate to. For example, with a sockets circuit, the regulations understandably require that a CPC be run to every socket and (perhaps more relevant) FCU. However, if a Class II item of equipment (with a 2-core supply cable) is fed from that FCU, there clearly cannot be a requirement for CPC to be run 'all the way' to the actual item of equipment. I realise that the receiver is not being 'fed by an FCU' in that way, but the same logic should also apply - i.e. if the cable to the Class II receiver comes directly from the boiler, then it's probably the boiler which is "the point in the wiring" to which a CPC must be run, not the receiver.

I'm not necessarily suggesting that any of this is particularly sensible, but I'm describing 'how it is', and how 'they' seem to be thinking about it.

Kind Regards, John

 

[JohnW2]

(1) a future change of equipment that does require an Earth

That's been discussed but, as I said, there is a limit to the extent to which regs should, or can, anticipate what (perhaps very silly) changes might happen to the installation in the future.

(2) an accidental nail or screw through the cable has a good chance of touching the Earth conductor and thus avoiding live metal projecting out of the wall / floor

That's also been discussed in the past. If that were the consideration, there would then presumably be a requirement for all cables to have a CPC, but (to the best of my knowledge) that is not the case. If there is a CPC supplied to an accessory or "point" in the installation by one cable, then there is not any requirement for any other cables to that accessory/'point' to also have a CPC.

Kind Regards, John

 

[JohnW2]

maybe a lack of earth is considered more dangerous than a spur, off a spur

Maybe, but that was just one random example I pulled out of the air. The general point is that regs simply cannot try to anticipate and try to address every possible incorrect change that could be made to an installation in the future.

For just one other example, they might ban OPDs >20A on sockets circuits, in case someone in the future 'extended it' with 1.5mm² cable.

Kind Regards, John

 

[bernardgreen]

there is a limit to the extent to which regs should, or can

Read the regs, then add common sense to the equation, that is a good way to decide what to do

 

[JohnW2]

Read the regs, then add common sense to the equation, that is a good way to decide what to do

It is, but we are talking about a regulation which appears to exist to make it more difficult for people to contemplate doing something that is forbidden by regs (installing a Class I item without an earth), without any need to bring common sense into the equation.

Kind Regards, John

 

[AndyPRK]

That's been discussed but, as I said, there is a limit to the extent to which regs should, or can, anticipate what (perhaps very silly) changes might happen to the installation in the future.

Sadly I think it happened alot. Hence why the regulation was introduced

 

[JohnW2]

Sadly I think it happened alot. Hence why the regulation was introduced

Maybe, but it does still seem a little odd to me.

What you are suggesting would make some sense if the situation had been that during the decades prior to the regulation, all light fittings and accessories had been Class II but then "it happened a lot" that people started changing them to Class I replacements, but I would have guessed that the tendency might well have been in the opposite direction. If you go back a long way in time, many were Bakelite, or even ceramic, but a lot were also metal, but by the time the reg cam along, 'plastic' was becoming the fashion.

Having said all this, trying to guess what was in the minds of those who wrote a regulation many decades ago is perhaps a rather futile exercise!

Kind Regards, John

 

[AndyPRK]

We certainly see a number of instances of people fitting metal switches without a cpc being present

It’s not just light circuits though

 

[ericmark]

If we read the report on the death of Emma Shaw the earth had been lost due to a nail in the wall, and had the inspection and testing been done correctly this should have been identified before the accident and so prevented her death, it was not any equipment which caused the live water on the floor, it was simply the wiring, so from that we can say yes there is a good reason for provision of an earth even if not used at the device.

 

[ericmark]

As to a class I receiver, with Nest Gen 3 the heat link is class II but it states if you power the thermostat from the heat link an earth should be run with the 12 volt supply, I don't know why, just read what it says.

 

[JohnW2]

We certainly see a number of instances of people fitting metal switches without a cpc being present.

We do.

It’s not just light circuits though

I can't say that I've personally seen anything other than a lighting circuit without a CPC, at least not for many decades, have you? However, what we've been discussing here is not so much 'circuits without a CPC' but, rather, individual cables within a circuit (like the one supplying a thermostat) not having a CPC.

Kind Regards, John

 

[JohnW2]

... so from that we can say yes there is a good reason for provision of an earth even if not used at the device.

As I wrote in response to bernard, if that was their thinking then the regs should require that every cable should have a CPC - but, as I said, to the best of my knowledge that is not the case.

Kind Regards, John

 

[RF Lighting]

It a black and white requirement. It makes sense why it is required and it’s not difficult to comply with at all.
There is nothing gained at all by not fitting one. The only reasons you would want to omit it is due to penny pinching or incompetence.

 

[JohnW2]

It a black and white requirement. It makes sense why it is required and it’s not difficult to comply with at all. There is nothing gained at all by not fitting one. The only reasons you would want to omit it is due to penny pinching or incompetence.

It's certainly a 'black and white' requirement, and the rest of what you say is reasonable in relation to something that is clearly a hard-wired part of the installation.

However, as I've said, I think the OP moved the goalposts a fair bit when he started talking about a Class II wireless thermostat receiver connected to a boiler by a multi-core flexible cable, in which case I wonder whether that item actually qualifies as 'a point or accessory' of the installation to which it is required to run a CPC.

Let's face it, it's theoretically possible that the item might come with a pre-fitted cable which had no core for a CPC. As I said, it's really analogous to any situation in which some Class II item is 'hard-wired' to an FCU - do you believe that the regs require a CPU to be run 'beyond' that FCU and, if so, how would you set about complying with the regulation if the item in question came with a pre-fitted 2-core cable?

Kind Regards, John