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

[ericmark]

We see again and again on this forum central heating wires up with the green and yellow wire over marked and used for some thing else other than earth.

We all know an earth is required for all installed wiring other than a pendent from the ceiling rose, so no question we know it is wrong and does not comply, however we see it so often on these pages just seen another here I was about to say it was not allowed, then stopped myself as it would likely serve no purpose and just worry the poster.

So should we bother telling people or not, and is there some thing they can do about it? I really don't believe all these thermostats have been DIY wired, the Persimmon home my daughter once had was clearly wired by either Persimmon or a contractor to Persimmon not the house owner and there was no neutral fed to the thermostat, as a result there was a large hysteresis, and I can understand why some one would use the earth wire as a neutral to reduce the hysteresis, however in theory Persimmon were breaking no rules missing out the neutral.

Central heating installers do tend to want the service work, and often put stickers on the boiler saying who they were, and we have been getting more and more EICR done, if lack of an earth is missed, could the home owner ask the inspector to foot the bill when the installer is no longer available, assuming he would have been at time of inspection.

OK missing earth likely does not mean potential danger and the inspector may not consider worth correcting, so maybe not even a C3, but should it be listed? We have got rid of code 4, so maybe it shouldn't?

For wireless thermostats I only know of one receiver that does not need a neutral, the Nest e, not seen any others, so should we point it out, as it has been with this post or shrug our shoulders and say nothing.

The same with 12 volt down lights converted to 230 volt, so often no earth to the lamp. And with both thermostats and down lighters often nothing to connect an earth to even if it was there.

 

[EFLImpudence]

You could instead ask why the regulations state that something that is not needed must be fitted.

 

[ericmark]

You could instead ask why the regulations state that something that is not needed must be fitted.

That is a good point, when the regulations came out for RCD protection I noted there was nothing to say it does not apply to SELV which clearly must be the case, due to the S for separated.

Looking at two regulations sorry only got old book

514.4.2 Protective conductor
The bi-colour combination green-and-yellow shall be used exclusively for identification of a protective conductor and this combination shall not be used for any, other Purpose.
Single-core cables that are Coloured green-and-yellow throughout their length shall only be used as a protective conductor and shall not be over-marked at their terminations, except as permitted by Regulation 514.4.3.
In this combination one of the colours shall cover at least 30 % and at most 70 % of the surface being coloured, while the other colour shall cover the remainder of the surface.
A bare conductor or busbar used as a protective conductor shall be identified. where necessary, by equal green-and yellow stripes, each not less than 15 mm and not more than 100 mm wide, close together, either throughout the length of the conductor or in each compartment and unit and at each accessible position. If adhesive tape is used, it shall be bi-coloured.

411.3.1.1 Protective earthing
Exposed-conductive-parts shall be connected to a protective conductor under the specific conditions for each type
of system earthing as specified in Regulations 411.4 to 411.6.
Simultaneously accessible exposed-conductive-parts shall be connected to the same earthing system individually, in
groups or collectively.
Conductors for protective earthing shall comply with Chapter 54.
A circuit protective conductor shall be run to and terminated at each point in wiring and at each accessory except a
lampholder having no exposed-conductive-parts and suspended from such a point.

The last bit means we need to run an earth even when not used, but so easy with BS 7671 to read a regulation which only applies to a certain thing, like caravan, or bathrooms and one has missed some preceding part, so

410.3.3 In each part of an installation one or more protective measures shall be applied, taking account of the conditions of external influence.
The following protective measures generally are permitted:
(i) Automatic disconnection of supply (Section 411)
(ii) Double or reinforced insulation (Section 412)
(iii) Electrical separation for the supply to one item of current-using equipment (Section 413)
(iv) Extra-low voltage (SELV and PELV) (Section 414).
The protective measures applied in the installation shall be considered in the selection and erection of equipment.
For particular installations see Regulations 410.3.4 to 410.3.9.

does that relate to 411.3.1.1? What it seems to say is 411 or 412 or 413 or 414 so if that is the case, if 412 applies do you need to comply with 411?

 

[bernardgreen]

I noted there was nothing to say it does not apply to SELV which clearly must be the case, due to the S for separated.

Not having an Earth in SELV ( Separated Extra Low Voltage ) circuits is OK, until the separation in the power supply unit fails and mains voltage conductors come into contact with the SELV conductors.

Where the SELV is from a wound transformer with split bobbin or twin bobbins the risk of loss of separation is very low. When the SELV is from a Switched Mode Power Supply ( SMPS ) the risk of loss of separation is much higher. With some SMPS units the risk is ( in my opinion ) too high. My opinion is based on having examined a few failed SMPS modules

 

[EFLImpudence]

What it seems to say is 411 or 412 or 413 or 414 so if that is the case, if 412 applies do you need to comply with 411?

Even if you argue that, 411 is about ADS. A CPC is not required for that in the cable when not required by the appliance.

Does it not say somewhere that:
A circuit protective conductor shall be run to and terminated at each point in wiring and at each accessory except a
lampholder having no exposed-conductive-parts and suspended from such a point.
is so that a Class 1 appliance can be fitted in the future?

I am sure it does/did but cannot find it.

As that is the case, then it should not really be a regulation.

 

[ericmark]

To @bernardgreen I seems some publications call it safety extra low voltage, and I see your point about needing on leg earthed which would make it PELV (protective extra-low voltage). An extra-low voltage system which is not electrically separated from Earth, but which otherwise satisfies all the requirements for SELV. or Functional extra-low voltage (FELV). An extra-low voltage system in which not all of the protective measures required for SELV or PELV have been applied.

To @EFLImpudence I gave the reference 411.3.1.1 Protective earthing which I have always seen as the bit that changed in 1966 when we were required to take an earth to a light fitting even if not used.

The point remains, I have criticised many an installation were the green and yellow cable has been over sleeved or marked, I still feel it is wrong, too easy for a sleeve to fall off, or more likely never fitted, but what should one advise a person who finds it already do to do about it?

Maybe it should have been a pole, ignore it, tell them to change wiring, etc. Last pole I tried I did it seems give the right options, so you buy a house, the boiler has a sticker installed by Joe Blogs 2004 and there is no earth to the thermostat, that seems to have been there some time, and the earth coloured cable is used as SL, so can you phone Joe Blogs and demand he sorts out the mess FOC?

 

[bernardgreen]

It is wrong to use Green/Yellow for anything other than Earth, likewise sleeving another colour wire with Green/Yellow sleeve for use as an Earth is wrong.

If Green/Yellow sleeve fall off a Brown wire during a re-wire then it could happen that the Brown wire is assumed to be a Live and is connected to Live and not to Earth, thus creating a very dangerous situation at the other end of the cable

Bare copper can and if Earth should be sleeved Green/Yellow

 

[JohnW2]

Does it not say somewhere that:
A circuit protective conductor shall be run to and terminated at each point in wiring and at each accessory except a
lampholder having no exposed-conductive-parts and suspended from such a point.
is so that a Class 1 appliance can be fitted in the future?
I am sure it does/did but cannot find it.

That is obviously what most/all people seem to believe as to the reason for the regulation and, like you, I'm pretty sure that I have seen that explanation 'written' somewhere, but I don't think it is (or ever has been) written anywhere in BS7671.

As that is the case, then it should not really be a regulation.

I suppose some people might say that, if taken as a generalisation, that is perhaps debatable.

We have often discussed, and agreed, that there is a limit to how far (if at all) the regs should consider what changes (particularly 'idiotic' changes) might be made to an installation in the future but, nevertheless, there are other cases where they do. For example, the requirement for 'identifications' of conductors (by colour or whatever) has absolutely no relevance to the safety of an installation so long as nothing is 'done' to the installation.

Kind Regards, John

 

[Deleted member 267285]

Even if you argue that, 411 is about ADS. A CPC is not required for that in the cable when not required by the appliance.

This is what I was trying to ask in another post, because Siemens wireless thermostat’s say no earth is required, yet I’m told I still have to provide one? Supply the cpc and terminate in a chock block. Makes no sense whatsoever.

 

[JohnW2]

This is what I was trying to ask in another post, because Siemens wireless thermostat’s say no earth is required, yet I’m told I still have to provide one? Supply the cpc and terminate in a chock block. Makes no sense whatsoever.

The 'sense', if that's what one calls it, is generally assumed to be what EFLI said, namely ...

.... is so that a Class 1 appliance can be fitted in the future?

Kind Regards, John

 

[AndyPRK]

The requirement came about, as later on people were extending circuits (which did require a cpc) from somewhere that didn't require one, and not bothering finding a cpc as it was too difficult.

But you should NOT be extending a circuit from a thermostat

 

[JohnW2]

The requirement came about, as later on people were extending circuits (which did require a cpc) from somewhere that didn't require one, and not bothering finding a cpc as it was too difficult.

As I implied, that was presumably the thinking but, as I also said, there is clearly a limit to how far regs can/should attempt to anticipate (incorrect) changes to the installation that may be made in the future.

The same logic would presumably result in unfused spurs from ring finals being 'banned', since people could subsequently 'extend' that circuit from that spur, wouldn't it?

Allowing unfused spurs comes with the caveat that they must not be subsequently 'extended'. If lighting circuits without CPCs were allowed (by current regas) that could presumably come with a caveat that it must not be subsequently used to supply a Class I item, couldn't it?

But you should be extending a circuit from a thermostat

Is there a 'not' missing from that sentence? Of course, it's not just a matter of 'extending a circuit'. Using the same logic as for lighting, they might argue that someone might subsequently want to change the thermostat for a Class I one (if such an animal exists!).

Kind Regards, John

 

[Deleted member 267285]

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?

 

[AndyPRK]

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

 

[Deleted member 267285]

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

The wiring generally comes from the boiler, which is earthed, from a spur which is earthed? All I got told was to supply the earth wiring, so could be tested - I’m guessing IR, as cpc not connected at receiver and boiler?