What gauge of wiring?

Hardwiring a new Eufy 1080p video doorbell to existing wiring in a US home circa 1995 with mechanical doorbell chime. I only have one doorbell. Could not find any info on the gauge wiring recommended. I have 22 gauge which is the the diameter of a paper clip. Ring does not recommend this saying it is unstable for video doorbells. Other questions on this forum suggest there could be a potential for fire. I have about 10ft up and then 30ft across to where the doorbell chime is located in the kitchen and another 20-30ft to the transformer in the attic. I purchased a 24V/ 40VA transformer, existing is 5V/10VA. Would one recommend a beefier gauge wiring, possibly 18 gauge, to make this more reliable and safe? And if I need to change wiring should I run the wires directly from the front door and bypass the chime altogether? Any help or links to other answered questions on this forum would be greatly appreciated.

That’s a pretty long run, and I probably would suggest replacing it with 18ga bell wire. However, assuming the doorbell only pulls 0.3 amps @ 24v then your existing wiring should be fine.


The higher voltage might cause problems with your chime - more power available, if it is a simple mechanical chime it might just result in hitting harder. But that might make it too loud, or cause damage over time. Check what the chime is rated for.

22gauge wire is not rated for your available current with the old transformer - 2 amps of current over a 5V/10VA circuit. But it doesn’t matter much, because the current flow is very intermittent (only significant when the doorbell is pressed). As long as nothing shorts the wire or connects it to ground…

The answer is that the existing wire will most likely “work”, and it won’t directly melt or cause issues as long as everything is hooked up correctly and no damage is done. But if you get a partial short somewhere that causes more current to flow to ground (mouse gnawing on cable, etc), then you might have a fire later because the cable can’t handle that flow. And with the new transformer, even though the current is lower the available power is higher, so the consequences are more likely to be bad.

Thanks lane03. Does that include the amps drawn from any video or motion detecting. Do not no the internal power requirements for each function of the doorbell. I am not using the old mechanical chime so could technically lower the length of run if I can wire directly from the Eufy box to the transformer. My understanding is that the jumper on the old chime keeps the old chime from drawing power and removes it from the equation.

Thanks TahaEng. My understanding was the old chime is rendered useless in a Eufy wired doorbell, hence the jumper. Doesn’t the old chime take a lot of power? I am happy to use the included plug-in chime even though there isn’t a “normal” ding-dong sound that I like, I digress. I am sensing that if I can, I should use 18 gauge wire just to be safe. I prefer to eliminate any “most likely” scenarios. Can one wire directly from the doorbell to the transformer and bypass the old chime or does that help to complete the circuit?

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You should be fine running wire directly from the transformer to the doorbell. If you want to increase the wire size, its probably a good idea, but the doorbell only draws 400 ma when the chime is rung so keeping the old wire wouldn’t hurt if its in good shape.

Not sure what amps it pulls when recording, but it should match up to what the label says on the back of the doorbell, which is 0.3 amps at 16-24v. You’re correct on bypassing the chime and yes you can run both wires directly to the transformer if you wish (that’s what I did) but as long as you bypass the chime you should be good.

I’m not sure of the specifics on using that doorbell with the old chime or not - I have another brand, that will work with the old chime with a slight wiring modification (although not perfectly, so without might be better). It sounds like from what others have said that isn’t an option here.

22 gauge wire is undersized for your power supply - not for the load, which will never be much. At these voltages, the limited power limits the damage that can be done. These are class 2 circuits per the NEC, and that is an area I am not as familiar with - the transformer should be labeled as class 2 though, inherently current limiting so you don’t need a fuse or breaker. The voltage drop due to the resistance of the cable itself is probably the concern that the Ring doorbell doesn’t recommend - that can be significant for a 60-70 ft run as you describe. But you have a 24V power supply, and these typically work with 16-30V at the doorbell, so probably not a concern there either.

You can bypass the chime completely if you aren’t using it. I personally would lean towards 18 gauge cables, but it probably isn’t necessary. Try it out, see what voltage you have at the doorbell with it hooked up, and you might be just fine with what you have.

Thanks pysailr for your response. The connection onto the back of the doorbell is a sheath of what appears to be 4 of these 22 gauge wires, all color coded. 2 are cut back flush with the brick wall so only 2 are long enough for the back of the doorbell. Can I double these up on both the doorbell side and the transformer side just to be sure I have adequate power or is this overkill? Trying to avoid fishing new wire through the brick wall and up into the attic but will if needed.

Thanks lane03. Will I need a resistor at the transformer side for this to work?

Thanks TaHaEng for that. If I shorten the distance and wire directly to the transformer is 22 gauge provide less “drop” and keep me from having any problems with the device itself. I am trying to avoid any interruption to service from the device. Looking for the optimum so it sounds like 18 gauge wiring is appropriate.

You can double the 22 ga wire on both ends and that will reduce the voltage drop. The only real problem with 22 ga. is it’s easy to break. It has enough current capacity for the doorbell, but 18 ga. is more robust.

I wanted to thank everyone for helping me with the wiring issue. Since folks use these forums to solve there problems when manufacturers are not as informative, I wanted to post the solution. I replaced the 5/10 transformer with a 16/24, beefier than recommended. To avoid the long travel distance from front door to chime to attic where the transformer is located, I bypassed the original chime altogether. I ended up using the 18 gauge 8 conductor shielded wire that was used in the house by builder for old doorbell. Since the wires were color-coded I was able to find the correct wires in the attic to rewire the transformer–no need to fish any new wire. Happy to say and knock on wood, I have not had one hiccup in over a month. I consulted an electrician thereafter at my house for a more complicated project and he gave it the thumbs up.