Wiring questions - installing new thermostat
- Thread starter jespencer
- Start date
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I'm none of those things.
If you don't like being called a dangerous and ignorant fool (which is not, abuse, BTW - it's the truth) then don't be one. Simples.
FFS - you went ahead and wired it up using a cpc as a live conductor?
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i do not think Doitall would use a three core cable to wire a thermostat that needed N termination to be utilised. Having read three pages, I get the impression he is saying there are many many instals where thermostats are wired with earth conductor (including the twin and earth) used as switch live connection. Equally galling is the practice of using 2.5 twin and earth to power a boiler, 13 amp fuse to protect a boiler circuit to add to the list
Which is quite correct, and I'm not going to argue that point.
The OP describes a green/yellow cable core of a multicore cable, not bare cpc, which he'd like to use as a live conductor.
Tell me which regulation does not permit the oversleeving of a green/yellow core of a multicore cable for use as a live conductor and I will gladly eat my words.
Electrical installations use conventions. For many years red was used to indicate live and black to indicate neutral in low-voltage AC circuits. There is no technical reason why an installation could not use black for live and red for neutral because, as you say, an electrician will never make assumptions and will test everything to understand a circuit before he works on it.
But will a DIYer test? Of course not. A DIYer will use a 30 year-old book that clearly states red is live and black is neutral. He will happily replace accessories or cut into cables and install junction boxes based on the assumption that the installation he is working on is wired to the standard convention. That is why it is highly dangerous and extremely foolish to ever install anything where a designated earth conductor as anything other than an earth conductor.
The OP may be looking at a multicore flex, however someone reading people who should know better telling him to use an earth conductor as a switched live may well assume that the CPC in T&E can be used in the same way. Neither situation is acceptable but the latter is significantly more dangerous as no matter how well you might think you can strip T&E there will be some exposed and uninsulated live conductor.
Green & Yellow, whether as part of a multicore cable or as a sleeved CPC must NEVER be used for anything other than earth.
But will a DIYer test? Of course not. A DIYer will use a 30 year-old book that clearly states red is live and black is neutral. He will happily replace accessories or cut into cables and install junction boxes based on the assumption that the installation he is working on is wired to the standard convention. That is why it is highly dangerous and extremely foolish to ever install anything where a designated earth conductor as anything other than an earth conductor.
The OP may be looking at a multicore flex, however someone reading people who should know better telling him to use an earth conductor as a switched live may well assume that the CPC in T&E can be used in the same way. Neither situation is acceptable but the latter is significantly more dangerous as no matter how well you might think you can strip T&E there will be some exposed and uninsulated live conductor.
Green & Yellow, whether as part of a multicore cable or as a sleeved CPC must NEVER be used for anything other than earth.
There are 1000s of posts and pics showing just that, where the OP is swapping like for like.
Nothing wrong with over sleeving or putting black/red tape on a multicore of any colour.
Did you know 9/10 Sparks couldn't wire a boiler and get it to work as designed and I would go as far as to say 99/100 sparks couldn't wire one of my installations without a line drawing.
100% of advising posters is knowing the product old and new, as Ericmark proved in this thread.
Be interesting to see what NICEIC, Napit etc have to say on the subject, even though it's not good practice and should be avoided.
Nothing wrong with over sleeving or putting black/red tape on a multicore of any colour.
Did you know 9/10 Sparks couldn't wire a boiler and get it to work as designed and I would go as far as to say 99/100 sparks couldn't wire one of my installations without a line drawing.
100% of advising posters is knowing the product old and new, as Ericmark proved in this thread.
Be interesting to see what NICEIC, Napit etc have to say on the subject, even though it's not good practice and should be avoided.
There's nothing in the OPs post to say that it is a green/yellow insulated core. It's more likely to be a CPC in a T&E that's been sleeved green/yellow - and depending on the size of the T&E, remember that the CPC may not be the same size as the other conductors.
If it is the latter, then it is not insulated through the length of the cable. So fail for suggesting it's OK to have a live, uninsulated core.
If it's the former, then fail for suggesting that a core which is colour coded to universally be a CPC/Earth can safely be used as a live.
In either case, you have advocated doing something that is not considered safe.
There is a difference between sleeving (say) a blue to use as a live, and sleeving a green/yellow. As above, there is no accepted situation where the green/yellow may be used other than as an earth/CPC. While it is recognised that any other core may well not be (in the case of blue/black) a neutral. Even if a blue or black is a neutral, then in safety terms, it is not considered "safe" in the way that an earth should be.
I'd suggest that latter statement says more about your installation than the abilities of a sparky.
But, I would suggest that there is nothing wrong in using a circuit diagram for anything but a "standard" (and simple) setup. In fact, that is the norm once you get past the really basic everyday stuff. Where it gets to be a problem is where people throw a load of stuff in, wire it in a non-standard or non-obvious way, and then do no documentation - or expect someone else who is not familiar with the installed kit to wire it without instructions.
And lastly, sitting on the sidelines, I can say I've seen plumbers I wouldn't trust to fill a kettle, and electricians I wouldn't trust to plug it in. On the whole, the situation seems worse in the plumbing world - partly I guess because apart from gas work (and Gas Safe registration), there doesn't seem to be any enforced standards in the plumbing world, while in the lecky world it's not easy to run a business without being a member of one of the trade groups (who have membership requirements). That's not to say both trades don't have a lot of good, competent, and honest people in them ...
No I didn't know that, but then that is because it is a false statement. A typical boiler control circuit (internal) or heating control circuit (external) is going to be no more complicated then a typical motor control circuit or building management circuits. Both of which are far less likely to be worked on by DIYers with limited understanding of their purpose.doitall said:
As for the diagrams, any good electrician will produce detailed diagrams for circuits that are not simple. It is standard practice.
I would be surprised if 9/10 electricians couldn't wire a boiler, or if 99/100 electricians couldn't wire any fixed installation when given the requirements. If they couldn't then I would not consider them to be electricians in the first place. There will be bad electricians but 90-99% are not in that category.
Electricity follows observable rules of physics and once you are trained/able to understand those rules then it is just a case of applying them to whatever convention you are working with. You know... those conventions such as not using an earth conductor for any purpose other than being linked to earth. The only time most electricians may have difficulty understanding the circuits you work on may be when you have been using dedicated earth conductors to carry switched lives as the OP in this thread has been dangerously advised.
Earth conductors must be reasonably assumed to be connected to earth and not used for any other purpose. When you cut into an existing cable or replace an accessory/appliance you will always test to ensure you know what each conductor carries. (DIYers may not.) However that does not change the fact that the designated earth conductor is just that - designated for earth. You may be sleeving a blue wire to show it is a switched live but it would always have been capable of carrying current. A designated earth should never carry current except in a fault condition in order to protect life and property. Doing so is a direct violation of BS7671 514.4.2 which states that cables coloured green/yellow throughout their length should not be used for any purpose other than as a protective conductor and may not be over marked at their terminations other than to aid circuit identification as permitted by Regulation 514.5.2.doitall said:
In which case there are 1000s of posts by, and pictures of work done by, dangerous ignorant people like you.
There will be several people killed on the roads today - perhaps you'd like to advise the OP to drive dangerously because thousands of other people do so?
Yes there is, but you are so thick that you don't understand that.
Apart from for twin & earth, where the separation of cpc is obvious and defined, IIRC there is no standard for multicore cable which stipulates or allows different cores of the same cable to have differing insulation characteristics based purely on the colour applied to the core sleeve.
It states single core cables quite clearly. This is for the benefit of problems which may arise from incorrectly identifying singles in conduit and trunking.
It states they may not be numbered other than for circuit identification, nothing mentioned about over sleeving.
A multicore cable, when the outer core is removed to expose the cores, becomes a collection of single core cables as far as identification is concerned. It makes no difference how they are grouped, whether it be singles through conduit or a multi-core flex/T/3C+E/etc - when the cores are exposed then identification at the terminations will not be able to override the cable colour/pattern. Green and Yellow cable is designed for one purpose only, for use as a protective conductor. Regardless of any rules or regulations you should never deviate from safety standards.
We know all too well of the people who come onto the electrical forum daily to ask why their new bedroom light switch now turns on and off their kitchen lights as well, because they have blindly copied switch positions from the old switch or grouped cables by their colours and they expect it to work. Some DIYers will always do that. Anybody installing a circuit that carries normal current through a CPC is playing with death. Maybe not theirs, but possibly the next person to work on that circuit. How many new metal light switches are being fitted to three way lighting circuits where the the CPC is used as LI/L2/C and are being operated daily with no CPC present to protect the user? And how many times each year does a DIYer (or an electrician who ought to know better) splice into a TC+E cable to install a new light and then either blows up the joint/fitting or makes the new fitting live when re-energising the circuit? The ones we hear about on this forum will only be a small selection.
As pointed out in the other thread, 514.4.2 is not the only regulation that could apply.
At some point we have to stop looking to regulations to protect us and start using common sense. Ask yourself what the authors of BS7671 intended with 514.4.2, then ask yourself why the same would not apply to a T&E or any other multicore cable. You have already stated the intention - I quoted it above.
On the contrary, identification at the terminals does override the colour of the cable sheath, and is done quite regularly. By over-sleeving green/yellow the core identification has changed to whatever you wish it to be. The original colour combination is being superseded, you're not using that colour combination to identify the function of the core as a cpc any more. That's where the common sense must be made, and why I'm not trying to hide behind regulation, otherwise we'd never over-sleeve anything.
Many DIY users get muddled up or baztardise perfectly sound installations, and not all of the resulting confusion or non-compliances can be accommodated for in design. Examples will include:
- Incorrectly identifying yellow cores as cpc
- Incorrectly identifying blue cores as neutral (pre 2004 wiring)
- Installing class I fittings or accessories in class II installations
- Spurring from a spur.
I agree that that the cpc in T+E or 3+E should serve no other purpose as that's how its intended by design, same as cable armours and sheathing.
Many DIY users get muddled up or baztardise perfectly sound installations, and not all of the resulting confusion or non-compliances can be accommodated for in design. Examples will include:
- Incorrectly identifying yellow cores as cpc
- Incorrectly identifying blue cores as neutral (pre 2004 wiring)
- Installing class I fittings or accessories in class II installations
- Spurring from a spur.
I agree that that the cpc in T+E or 3+E should serve no other purpose as that's how its intended by design, same as cable armours and sheathing.
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