type of wires for central heating components?

[gas4you]

Not disagreeing at all with you Simon, but I was once told by a sparks that the reason you shouldn't sleeve each end of the earth wire was that if it was cut in the middle then no one would then know it had been used as a phase.

Can't see this applying to most ch installations which are usually confined to airing cupboards though, only if flex is used under floor boards, which I believe to be incorrect also.

I stand to be corrected though

 

[simond]

These are old wives tales, Dave.

You can use flex providing it is adequately supported and protected. The Part P earth loop impedance tests have to be satisfied too, which rules out 0.5mm flex generally. We use Tower Flue Components 0.75mm five/six core.

And whilst i would be first to agree that using the core originally labelled green/yellow for another purpose sounds like a short cut, providing it is labelled at each end unambiguously no-one can touch you.

Yes, you could cut the cable mid length and if it were not tested you could make an incorrect assumption. But then I once found a plastic Keston flue pipe in the floor of a nursing home. Boiler kept cutting out. A plumber had tee'd in a sink waste to it.

 

[namsag]

Although not hundred percent sure i would be with simond on these points . We also use .75 heat resistant , I hope Agile is getting some tips on this topic as he used to use 2.5mm twin and earth cable to wire his boilers.

 

[WDIK]

goodness me.
should this be here or in the electrical section?

right, listen up, all cabling methods require a cpc
circuit protective conductor.

an earth.

in the event that multi core conductor is injured then it shorts to earth

all heating circuits should be protected via a 3A fuse.

minimum conductor sizes? well personally Id say 1.5 but with a 3A fuse yes you can go down to 0.5, but thats just shoddy.

ooh I just noticed Im a JIB approved electrician

doesnt mean anything

 

[andytheplumber]

I have been taught that you cannot use the earth wire for anything else but earth Sleeved or not.

 

[simond]

Andy, I have been taught otherwise, by an AMIEE lecturer.

I was of the same opinion as you, Andy, so he went to great lengths to show me that the regs do not forbid it and therefore it is legitimate.

Finally;

WDIK wrote:

right, listen up, all cabling methods require a cpc
circuit protective conductor.

an earth.

in the event that multi core conductor is injured then it shorts to earth

Nonsense. More old wives tales.
543.1 says that an earth conductor can be separate and does not have to form part of a cable.

I put it to WDIK that the CPC is not there to protect the cable but to provide indirect contact protection to connected equipment eg: boiler. Therefore all cables do not require a cpc.

The only exception is where the cable itself incorporates a metal sheath (eg: SWA. Pyrotenax) which need indirect contact protection because of the exposed metalwork. However this is rarely used in domestic heating systems.

 

[WDIK]

right

 

[simond]

Well, if you disagree (sarcasm noted) please point me to the relevant paragraph in the regs.

Because if it isn't there, it isn't so.

 

[WDIK]

I wasnt going to respond but I will this once.

I apologise for my lack of experience, I only did a 5yr apprenticeship, 8yrs at college and spent 34yrs in the industry.........

 

[andytheplumber]

The regulation now is that you cannot use Earth wires for anything else but Earth. Sleeved or not. I gets to confusing when someone has used the earth wires for a switched live and so on.

 

[WDIK]

circumstances

stick a spade through the cable and understand the purpose of a CPC
CIRCUIT PROTECTIVE CONDUCTOR

 

[namsag]

WDIK Not being funny but simond has asked for a link to this would it not be easier just giving it to prove him wrong and you right or vice versa

 

[WDIK]

Namsag, no I wont provide a link, probabley it doesnt exist, I didnt learnt my trade as neither did you from reading an article on the internet or by doing a part a P course, what it says in the 17th edition of the regs is only the tip of the ice berg, reading them and or understanding them does not give you any relevant experience and certainly doesnt make you an electrician.
a bit like reading the gas regs and claiming to be a gas engineer.

I was taught and when you think about it makes sense, if a cable were damaged by a conductive item then what ever damaged that cable would short the phase to earth and hopefully not leave live exstrainious metal work.

 

[namsag]

WDIK . Agree with your reply and yes it makes sense, but i hate to argue but if i do i will not only fight my case but put something there that can shut people up and prove me right. but i would say elec regs are a bit like the gas regs they can be interpreted differently

 

[WDIK]

explain 20 thread copper to me then

google it and you will see its ceased to exist