Is .75mm Five Core Cable OK For CH Programmer?

[plumbandplumber]

I'm helping my brother who has recently bought a house. The plumbers who installed the wiring centre box and programmer for his vented back boiler system put them in a ridiculous place. It's on the side wall inside airing cupboard down the side of the cylinder. There is a few inches between the cyl and programmer.

He can neither see the screen or even know what time it says. Any use of programming it would need a contortionist with a head the size of a tennis ball. All he can do is press the hw or heating buttons to turn them on or off.

So, it has to be re-located. It has several short lengths of T&E connecting it to the the wiring centre, which is a few inches below the programmer. Can I use .75mm 5 core cable to link prog to wiring centre? Is it man enough?

Many thanks.

 

[Masood]

0.75 is good for up to 6A so it should be OK, seeing as boilers only need a 3A fused supply.

 

[Jimbob]

yes 0.75 will be plenty

 

[GasmanxxxR1]

.75mm is good, but the earth will have to be a switch live so needs taping/sleeving

 

[lame plumber]

??? 5 core being used so why are you taping up the earth

 

[Nostrum]

5 core is 3 phase/line colours plus neutral and earth. If its a y plan you'll have live and neutral to power the programmer, plus h/w on, h/w off and htg on, all live hence using the earth as a line conductor.

if its an s plan you'll only need the 4 so you can bin it off completely.

 

[Billy Bob Bob]

5 core is 3 phase/line colours plus neutral and earth. If its a y plan you'll have live and neutral to power the programmer, plus h/w on, h/w off and htg on, all live hence using the earth as a line conductor.

if its an s plan you'll only need the 4 so you can bin it off completely.

the earth CAN NOT​ be used for anything else other than a earth it is there to protect the cable

 

[Nostrum]

Only twin and earth, flex can be sleeved. I was under the same impression as you but NICEIC have said otherwise.

you won't get 0.75mm2 twin and earth so we can assume, in this case, the OP is referring to flex.

 

[AWheating]

the earth CAN NOT​ be used for anything else other than a earth it is there to protect the cable

it can be used if there is no need to earth the item its wired to, ie double insulated. Many heating controls do not require an earth, you could argue that if a metal back box is used behind in the wall then you will want to earth this or if the cable is less than 50mm in depth inside a wall. which should also be protected by an rcd.

 

[lame plumber]

me I'd buy 6 core .75mm heat resistant flex for y plan, but he asked about 5 core originally, still like to use yellow and green for earthing myself and sleeve any others that are live, makes me feel more professional that way.

 

[plumbandplumber]

Apologies for causing some controversy. Yes, it's Y plan and it is flex I'm planning to use.

So, I'm now confused. Five core 0.75mm is sufficient to handle the load, but am I right in now thinking I can't use it because the earth would have to act as a phase wire? Do I understand it right that I'm not allowed to put tape on the earth to denote that it serves another purpose?

Perhaps it would just be easier to ask what wire/cables(s) the pros use to link a programmer to it's wiring centre.

 

[AWheating]

you can use the earth as a line conductor, but if you need an earth then you will need an extra core. If you were using twin and earth type cable you can not use the earth as a line conductor due to size and/or lack of insualtion.

0.75 is fine if protected by a 3amp fuse.

 

[Nostrum]

me I'd buy 6 core .75mm heat resistant flex for y plan, but he asked about 5 core originally, still like to use yellow and green for earthing myself and sleeve any others that are live, makes me feel more professional that way.

If you can find it, and are happy to pay for it, then this would be the best solution. It's not readily available though so 5 core is often used as described.

 

[AWheating]

stick in a wireless programmable room stat and fudge the cables 😉

 

[Nostrum]

Alternatively just use 2 x 4 core which will allow you 5 line conductors, 1 neutral and 2 c.p.c's if you need one (or even 2!)

 

[Nostrum]

stick in a wireless programmable room stat and fudge the cables 😉

Or buy an inspection mirror and pair of angled pliers and leave the programmer where it is

 

[GasmanxxxR1]

You could use 2x3 core flex.

Most programmers are double insulated with a plastic back plate, so i would say it would be ok to tape the earth wire with red insulation tape. I would say that 85% of the systems I work on are like this.

If im doing a full re-wire from scratch i use 6 core, but i think you have to order it in at the merchants

 

[GasmanxxxR1]

??? 5 core being used so why are you taping up the earth

Y plan programmer: L, N, HW on, CH on, HW off

 

[Nostrum]

You could use 2x3 core flex.

Most programmers are double insulated with a plastic back plate, so i would say it would be ok to tape the earth wire with red insulation tape. I would say that 85% of the systems I work on are like this.

If im doing a full re-wire from scratch i use 6 core, but i think you have to order it in at the merchants

Red tape? :6:

 

[GasmanxxxR1]

why not red

 

[Nostrum]

It's not a recognised line/live/phase colour now, brown grey or black. If you tape it red you should tape the neutral black as well.

 

[GasmanxxxR1]

im sure someone who is looking at it knows what it means, otherwise they shouldnt be touching it

 

[Billy Bob Bob]

your missing the point,the earth cable is there to protect the cable it does not matter if the clock or whatever is double insulated,it is against regs to use it as a control wire ,thats how fires start by not using a earth as its intended

 

[Roger Welton]

Cable sleeving is so cheap why not keep a bit on the van.

 

[lame plumber]

its also how lame gets the occassional belt going into an airing cupboard in the dark to find out whats wrong 🙂