What cables/wires for new boiler and controller

[seftonbarn]

I have the builders in doing some internal alterations to my bungalow. One of the rooms they are working on will be having a new conventional boiler fitted with the controller mounted beneath it (boiler in kitchen has packed up). I want to run the cables to the new boiler and to the central heating controller (leaving the connecting for the electrician later) so that they can be plastered over. My plumber is on holiday this week so i can't ask him which cables to put in, and I don't know who his electrician is. The system is a Y plan system. My old boiler has packed up the replacement is going in a different room. The current cable to the controller has 5 cores L, N, CH On, HW on & HW off there is no earth; is that right? If I do require an earth that will be 6 core cable and no-one seams to sell it. I can get 5 core cable from TLC. I feel something is amiss; my system is a very common one; surely if 6 core cables aren't a common supplied item then I don't need one. I assume it is 3 core cables to the boiler? One or 2? Or could I use 5 core? Do the cables to the boiler have to be a special type? Any help would be appreciated.

 

[Leesparkykent]

I have the builders in doing some internal alterations to my bungalow. One of the rooms they are working on will be having a new conventional boiler fitted with the controller mounted beneath it (boiler in kitchen has packed up). I want to run the cables to the new boiler and to the central heating controller (leaving the connecting for the electrician later) so that they can be plastered over. My plumber is on holiday this week so i can't ask him which cables to put in, and I don't know who his electrician is. The system is a Y plan system. My old boiler has packed up the replacement is going in a different room. The current cable to the controller has 5 cores L, N, CH On, HW on & HW off there is no earth; is that right? If I do require an earth that will be 6 core cable and no-one seams to sell it. I can get 5 core cable from TLC. I feel something is amiss; my system is a very common one; surely if 6 core cables aren't a common supplied item then I don't need one. I assume it is 3 core cables to the boiler? One or 2? Or could I use 5 core? Do the cables to the boiler have to be a special type? Any help would be appreciated.

what make and model is the new boiler?

 

[seftonbarn]

what make and model is the new boiler?

Thanks for taking the time to reply. The new boiler will be a Glowworm Ultracom 24 HXi,

 

[Octopus]

All cables should have a CPC

 

[seftonbarn]

Thanks for taking the time to reply. The new boiler will be a Glowworm Ultracom 24 HXi,

Thank you Murdoch. "All cables should have a CPC", yes just as I thought. So Should my current installation in fact be 6 core? Where can I buy 6 core? Is this normal? Or do I have some sort of special unique system?

 

[Leesparkykent]

Thanks for taking the time to reply. The new boiler will be a Glowworm Ultracom 24 HXi,

The boiler has pump over run so requires live, neutral, earth, pump live, switched live. As you have a y-plan you need live, neutral, earth, HW on, HW off and CH on connections to the programmer.

 

[Leesparkykent]

You can get 6core flex but depending on the run and installation method flex may not be ideal. I would run 1mm 6242Y and a 1mm 6243Y to the programmer position.

 

[ImpededLoop]

As Lee says.

If you need to buy drums of cable, you could buy one drum of 6243Y and run that twice (leaving you with a spare core) to save having to buy two different drums of cable.

 

[seftonbarn]

The boiler has pump over run so requires live, neutral, earth, pump live, switched live. As you have a y-plan you need live, neutral, earth, HW on, HW off and CH on connections to the programmer.

Thanks you for the swift response. So as I understand it I need 6 core cable for the programmer. Should this be 1.0mm squared? Where can I buy 6 core cable? Do I have a very special and unique system?

 

[ImpededLoop]

Thanks you for the swift response. So as I understand it I need 6 core cable for the programmer. Should this be 1.0mm squared? Where can I buy 6 core cable? Do I have a very special and unique system?

Lee has given you the cable references for "twin and earth" and "three core and earth" cables rather than 6 core flex. Using the cables Lee has mentioned is normal for this type of installation.

1.0mm will be fine.

You will also probably need 5 core heat resistant flex to the boiler from the programmer if it's adjacent to the boiler.

 

[Leesparkykent]

No you don't have a special and unique system it's a y-plan.

Some earths omitted for clarity on drawing.

 

[trypod]

[h=1]Cable 6 Core 0.75mm PVC Flex White - 50 Mtr Drum[/h]


Click main image to enlarge
Images are for illustration purposes only

• 

50 metres£62.27
(ex VAT) Quantity:

[h=2]Product Information[/h]
Part Number3186Y0.75WConductor Size mm0.75mmMaximum Current Rating6 AmpsNumber Of Cores6Inner Core ColoursRed, Brown, Blue, Black, Grey, White and YellowOuter Sheath ColourWhiteVoltage Rating300/500 VoltsMain ApplicationCentral Heating Applications, Boiler Control,Valves, Pumps etc. Not to be used in areas where the cable may be exposed to high temperatures or come into contact with grease or oil. Not Heat ResistantInsulationPVC Sheathed and PVC InsulatedConductorsStranded Flexible CopperNominal Area Of Conductor mm0.75mm

 

[davesparks]

Where is the power supplied from? Usually it will be a sfcu next to the boiler.
If this is the case then for a standard Y plan with wired room stat you will need 4 cores+cpc from the programmer (N, DHW on, DHW off, CH on) and 2 cores + cpc from the boiler (S/L and pump)
Plus 2 cores + cpc from boiler to programmer and again from programmer to SFCU.

Personally I would probably run 2x 3core&earth from a flush box behind the programmer to the airing cupboard then a 5 core flex up to the boiler and a twin&earth to the SFCU

If there is to be a wireless room stat receiver in the airing cupboard then you'll also need an L from the programmer (or boiler or SFCU)

 

[seftonbarn]

Everyone has been really helpful, many thanks. One more thing (from reading all of the above threads) can I sue standard 6243Y to the boiler or have I got to use heat resistant flex?