Why isn't there a 3186Y Cable (6-core)

Probably demand and (like Charles Renard's preferred numbers) it's often more efficient to make a limited number of things and waste a little by using one slightly too big, than make every possible size.


There might also be some manufacturing reasons - certain numbers of strands - e.g. 1, 3, 7, 19 etc pack nicely into an (approximation of) a circle - other numbers would need additional fillers and result in the same size cable overall despite the fewer cores - so savings might be even less than imagined.


So I guess either use a 7-core and waste on core, or use a 6242Y (L&N+cpc) + 6243Y (C,NO,NC+cpc)


   - Andy.

I'll be using 7-core.  But I bet some would use 5-core (of which one core is G/Y) and perhaps over sleeve the G/Y. Not my style though. Although that is what the original electrician brought in by the heating engineer did and then ran a seperate Green/Yellow for earth! 

Clive

You just never know when a spare core might come in handy. I am lucky to have an independent local electrical wholesaler that will cut me any length of flex or cable from a drum and just charge pro rata discounted drum pence per metre. I do not have to stock drums of rarely used multicore flexes. Having said that I do use 5 core heat resisting flex quite a lot for heating systems, and recently for an oil boiler supply where I had to connect L., N., E., H.W., and C.H. at the boiler supply plug. It was nice to have separate  H.W. and D.H.W. cores at the main junction box wiring centre, as this aids fault finding or alteration in the future. Previously the H.W. and D.H.W. L. had just been linked together.


Z.

AncientMariner:


It will, I guess, be down to demand, but for rewiring say a Siemens Wireless Thermostat where the Receiver Unit needs L + N  together with c + n/o & n/c  a simple 5-core cable would be so much more straightforward.

 

Wouldn’t only be required for an appliance that heats and cools to maintain temperature within a specified range?


Andy Betteridge

Wouldn’t only be required for an appliance that heats and cools to maintain temperature within a specified range?

Some motorised valves (e.g. some 3-port mid-positions ones) need a 'satisfied' signal to drive the motor to close one of the ports when no longer needed - the spring return only operating in one direction and so only works for one port.

  - Andy.