Multicore cable voltages

Ash4189 · Feb 13, 2019

Wiring RF thermostat receivers to valiant boilers...

We have been using standard 0.75mm 5 Core flex, from the receiver to the boiler (reference method B). Obviously the flex is carrying L-N-E at 230v and also two switch wires ‘boiler on’ ‘boiler off’ at 24v. However someone has made a comment on carrying band 1 and band 2 in the same cable, saying it’s not allowed. All conductors are insulated to 230v and the regs are like blurred lines.

Can anyone offer any advice?

Thanks

Midwest · Feb 13, 2019

Not sure about 1 & 2 in the same cable, but I think you could cause problems with induced voltages on the extra low voltage cables.

Spoon · Feb 13, 2019

Ash4189 said:
Wiring RF thermostat receivers to valiant boilers...

We have been using standard 0.75mm 5 Core flex, from the receiver to the boiler (reference method B). Obviously the flex is carrying L-N-E at 230v and also two switch wires ‘boiler on’ ‘boiler off’ at 24v. However someone has made a comment on carrying band 1 and band 2 in the same cable, saying it’s not allowed. All conductors are insulated to 230v and the regs are like blurred lines.

Can anyone offer any advice?

Thanks

Your setup complies with reg 528.1 (ii), so it is allowed.
As above, Induced voltage may be a problem.

[ElectriciansForums.net] Multicore cable voltages

Bobster · Feb 13, 2019

No issues as long as the insulation of the conductors is rated at or greater than the maximum voltage it will be used with.

Induced voltage shouldn't be an issue here, as the 24V can be seen as a digital signal, either on or off. This depends on the impedance of the input to switch the boiler. Does it trigger a relay or is it to an input on a circuit board?

Ash4189 · Feb 14, 2019

Rob said:
No issues as long as the insulation of the conductors is rated at or greater than the maximum voltage it will be used with.

Induced voltage shouldn't be an issue here, as the 24V can be seen as a digital signal, either on or off. This depends on the impedance of the input to switch the boiler. Does it trigger a relay or is it to an input on a circuit board?

The connection is a 24v RT terminal on the boiler circuit board. The Switching is done within the receiver.