vaillant ebus control wiring 230v & 24v

[bonesetter]

I'm installing the VR65, VR10 and VRC470 and outside thermistor in place of Honeywell programmer and room stat.

Is it ok to run ebus signal in the existing 5core with the 230vac supply to the boiler or should I segregate into two separate cables and should cable to boiler be heat resisting type instead of PVC?

 

[mickyg]

they should be seperate. The voltage in the live wires can interfere with the ebus signal. Its against wiring regs anyway and generally bad practice.

 

[bonesetter]

Should cable be heat resisting spec?

 

[simond]

Yes.

 

[kevindgas]

Yes.

why? none of the items apart from boiler produce any heat and that is very low

 

[UpgradeME]

Is it ok to run ebus signal in the existing 5core with the 230vac supply to the boiler or should I segregate into two separate cables and should cable to boiler be heat resisting type instead of PVC?

I asked Vaillant if I could re-use my original 230v cables to which they replied yes! with the following provisio;

Where sensor and ‘eBUS’ cables run in parallel with 230 V cables over a length of 10 m, they must be separated by at least 25 mm.

The vast majority of my re-used cabling was already run seperately, there's maybe 1-2m max where it's likely in the same trunking and I've had no issues with eBus signals.

 

[kevindgas]

i always run ebus and 240 together from boiler to switch on wall in a 5 core then seperate from there to stat/time etc never had an issue with it

 

[Onetap]

I'm installing the VR65, VR10 and VRC470 and outside thermistor in place of Honeywell programmer and room stat.

Is it ok to run ebus signal in the existing 5core with the 230vac supply to the boiler or should I segregate into two separate cables and should cable to boiler be heat resisting type instead of PVC?

Ask on the Electrical forum.

My understanding is that legally you can only run 230V and signal cable together, in the same trunking, if both cables are rated for the higher voltage; otherwise they need to be separated. The 5 core is rated for 230V, but only if used as a double-insulated cable, it is not intended for different voltages on different conductors. I'd think that is a no-no.

It is bad practice to run 230V and control cables in parallel because you can get a signal (noise) induced in the control cable that is large enough to affect the actual control signal. The control cable should be screened twisted pairs, with the screen connected to an earth at the controller end only. The only time I tried using non-screened cable that was run parallel with mains (a lash-up using an existing telephone cable for the themistor, to get a system running) there was a perfect sinusoidal signal on the thermistor input and the arrangement was unusable until re-wired correctly.

I have the same arrangement, with the e-bus cable behind the boiler, the boiler being on the stand-off frame. There is no significant heat emitted from the boiler. If the cable is kept away from the hot pipes, pvc insulation is OK.