I've just bought a reolink wifi doorbell, which says you can use the previous doorbell wiring to connect it up, so long as it's got the right voltage.

I'm pretty sure mine currently doesn't as the current transformer says 8V 1A (which is 8VA).

The reolink needs 12-24V 30VA. So i need to get a new transformer. That's ok, i think i can handle that part.

My actual question is that the current doorbell is wired up using what i think it's telephone wire. 3 pairs of blue, green, orange wires, all with white (so each pair is of white green and green white etc).

It seems to me, that they've used both pairs for each connection, i.e. in the doorbell switch each of the connection has both of the pair of one colour. I'm not sure if this is to split the current over them or something?

So, now that I'm putting more juice to the smart doorbell (30VA instead of 8VA) do i need to replace the wire? I hope not as this is all in the walls already and will be a massive headache to remove it.

1 Answer 1


In short, you should be able to use existing wiring, if it's not damaged. Safest would be to use a transformer with somewhere between 16 and 24 VAC output. Check that wire size is 1 mm diameter or greater.

The explanation for that statement:

The voltage matters only regarding insulation of the wire, and any insulation that can handle 8 VAC likely is safe with 12-24 VAC. The main danger here might be electric shock, and some electrical codes consider anything less than 50 VAC "low voltage", so if the old wiring meets code, the higher voltage transformer should no problem.

It's current that heats the wire. The old wire handled 1 ampere, so at 12 VAC, it would need to handle ~2.5 A for the new doorbell, at 16 VAC current would ~2 A, and at 24 VAC, ~1.2 A. However, bell wiring is usually heavier than needed for current flow, because a thinner wire would break easily during installation. Most US bell wiring is ~18 gauge (~1 mm), rated at 2.3 A continuous current, or even thicker. Check wire size with a wire gauge or caliper. Since the new device likely does not draw 30 VA continuously, 1 mm wire should be fine. If you want to leave a margin for error, use a 16 VAC up to 24 VAC transformer -- higher voltage means lower current, if the new doorbell has an efficient power supply.

  • Hi, thanks for your reply. So a few additional points to add. 1) I'm in UK so US codes won't apply (but hopefully they'll be similar enough) 2) the wire is telephone wire which I'm told can handle 0.15A or 0.3A when paired up, as mine currently is. 3) I've now looked at the adaptor that you can use from mains electricity and it's rated at 16V 0.5A so the doorbell will run at maximum 0.5A, so if i triple up the wires I can in theory get up to 0.45A which i think is good enough. Commented Jul 28, 2023 at 12:45
  • Ah! This is truly telephone cable! In the USA, in older installations, phone cable was four (or more) hard solid copper wires, about 18 Ga. (1 mm), and later, was very low current tinsel wire (en.wikipedia.org/wiki/Tinsel_wire), which appears to be what you have. A close-up photo of the stripped wire would help to be sure, but yes, running wires in parallel increases the current rating. However, the original question stated 30 VA, which means that at 16 VAC, it would draw 2 A. Which statement is correct? "the doorbell will run at maximum 0.5A," or "reolink needs 12-24V 30VA?" Commented Jul 28, 2023 at 16:48
  • Well the original question of 30VA was based on the manual/app installation section. However, with the doorbell comes a power adaptor that means you can power it from the mains. On the adaptor it specifies that the adaptor can only supply 16V and 0.5A, so I'm assuming the 30VA is an ideal or something, but the reality is you couldn't get that from the adaptor so it's not necessary Commented Jul 29, 2023 at 17:21

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