Following instructions but seem wrong, what I am doing wrong?


I am trying to wire up the wireless receiver by following the instruction on guide. I am having trouble wiring up the live and natural wires. The connector terminal block seems to only allow one wire at a time and I can't seem to add two wires at the same time, I have unscrewed it but no luck. The Tado wire is big. I've added photos. Not sure what I am doing wrong.

Any help would be apricated

This is the instructions

this is the power cable live wire

This both power cable live wire and Tado live wire together.



  • If the two wires really won't both fit in the same connector, you might need to put them both together in a bigger connector block and wire that up to the boiler with another bit of spare wire.
  • Unfortunately I'm not a plumber or a electrician so I am not qualified to do that or even know where to begin todo that. My boiler is a Baxi 600 and I found this in the manual, not sure what to make of it

    here is the manual

  • I'm not really happy with instructions that tell you what to do without why; when something doesn't work out, you tend to be stuck. From the diagram. it looks like the smaller side of the connection strip is where you wire up the tado boiler control relay (to b1 and bk2), and the rest of the connections are just to power the tado wireless receiver? So one could probably just put a separate lead and plug on it to plug it into a walloutlet instead of putting it in parallel with the boiler mains supply on the bigger connector block where it doesn't fit.

    There might be some of those somewhat over the top UK electrical rules in play here that don't allow you to just DIY it like we would here on the barbaric continent.
  • The flex you are trying to attach is oversized for amount of power the Wireless Receiver will draw. The Live wire that powers the boiler is fitted with a ferrule which will make it even harder to to get two wires in the terminal block. Strictly speaking stranded wires and ferruled wires should not be mixed. Either both have ferrules or both are stranded and twisted together. Ideally you need to use a multi core flex with a smaller diameter.

  • epone
    edited December 2022

    I do feel quite stuck. Unfortunately the power location doesn't easily allow for a separate lead to be plugged in to use on a power outlet. The flex is on the Tado wires not on the power switch cables. What would a multi core flex look like?

    Here is the existing wiring. One is for the switch the other is for the old receiver.

    The existing receiver live wire is connected to the black cable. Not sure why its like that.

  • I seemsto me the thicker wires with the twisted strands are the ones that bring power to the boiler and the thinner ferruled ones are being used to daisy-chain it on towards the tado.
    It would probably be possible to get rid of the ferrule and just twist the strands of both flexes together to put them in the terminal block of the boiler.

    However, epone may not feel qualified to do that. Nothing wrong with that, I would certainly hesitate to work on say my car's engine, the cooling circuit of my fridge or do a bit of heart surgery.
    They probably also lack a boxing room full of spare bits of wire, outlets, switches, light-sockets and plugs, and decades of practise tinkering around with replacing plugs of chinese pressure cookers, moving switches and outlets that /just/ needed to be moved a few centimeters because of the new furniture-layout, fixing broken cables of steam-irons, reattaching the vacuum-cleaner's cord that just wasn't long enough etc. that makes wiring up something like this feel more like being on the same level of complexity as baking a cake than the black magic you really ought to study for a few years...

    So, it might be better to get the village smith or a technical niece to come have a look on site, instead of well-meaning volunteers trying to help out over the internet. We can probably not do much more than nudge in the right direction...
  • You must use the fused wall switch, do not attempt to use a power outlet.

    The cable provided by Tado is what is referred to as multi core flex by electricians.

    Check the fuse in the wall switch. It's likely to be 3 Amp which means you could use a flex similar to the one in this link. The stated size of the wires is 0.75mm, which is good for up to 6 Amps and looks to be smaller than what Tado have supplied.

  • luteijn
    luteijn ✭✭✭
    edited December 2022
    "The existing receiver live wire is connected to the black cable. Not sure why its like that."
    See figure 37-> it's switching that black lead to the blue one over the brown and green/yellow ones. The black lead is live too. Using that and its blue wire as neutral, the existing control probably is leaching off some power for its display etc. You might do that with tado too, if you /can/ fit tado's brown wire in there, but yoy'd still have to get the two blue leads in the neutral connector block, which seems to me to be the same trouble as the browns give...

    It might be easier from the other side of the block. Just make sure you keep the original supply wires on the side they were on, so you don't bypass the fuses..

    Still surprising that with all the extra fuses, ring circuits, oversized plugs and switches on the outlets in use, it seems perfectly fine to use standard supply flex for switching (so the colors don't match typical use), and using mains voltage instead of something like 48V or less to control the burners.
  • So I had to hire a professional to fit the receiver. What he did was hook up the power switch to the receiver and from the receiver to the boiler. He used separate flexible cable from the receiver to the boiler. Looks like the very exact cables @GrilledCheese posted. I believe Potential Free Relay

    This is what the setup looks like, all is working as expected. I do like the scheduling feature, also already have saved some money.


  • Because of where the switch with the mains power is and the position of the boiler, this way makes sense. Having the tado box on a spur might have been preferable so it could be moved more easily in case of radio reception troubles.

    Interesting how the practices differ between countries, over here in Barbaria I think an outlet (with maybe a single pole switch, if that happened to be on hand and you bothered to wire it up, and of course no fuse) would have been used so you can physically unplug everything and make it safe to work on, instead of just having a switch (even if double-poled (?) and fused) with the flex coming out of the wall just like that. Of course, there's probably a reasonable rationale for doing it like this.