Fixes

Why your doorbell transformer keeps burning out

If you have replaced a transformer more than once, the second one did not fail for the same reason the first one did wear out. Something is still wrong, and there are only two candidates worth checking.

Last updated 2026-08-28

The short version

A mechanical doorbell drew current for about a second, when somebody pressed the button. A camera draws it continuously, all day, to stay awake on Wi-Fi and to record. The transformer in most houses was sized for the first job.

An undersized transformer supplying a continuous load runs hot. Running hot is how it dies. Fitting an identical replacement means fitting the same failure again.

If it burned out with the doorbell disconnected, stop reading about sizing. A transformer that fails with no load attached has a short somewhere in the wiring, and a bigger transformer will simply push more current into that short.

Work out which of the two it is

Disconnect the doorbell and wait

Take the camera off the wiring entirely and leave the transformer powered for a day. If it still gets hot, hums badly or trips, the fault is in the wiring and the rating is a red herring. Skip to the short-circuit section.

Read what is printed on the transformer

It will state a voltage and either a VA rating or an amperage. Volts multiplied by amps gives you VA. This one number decides everything that follows, and it is usually stamped on the body or on a small label beside the terminals.

Compare it against what your doorbell asks for

The requirement is set by the model, and the spread across one brand is wide. Check the figures below against the printed rating before you buy anything.

What the manufacturer requires

These are Ring's published figures, and they are worth reading closely because people quote a single number as though it covered the whole range.

Battery doorbells and Video Doorbell Elite: 8 to 24 VAC, 50/60Hz, 5VA to 40VA
Video Doorbell Wired: 10 to 24 VAC, 50/60Hz, 8VA to 40VA
Video Doorbell Pro, Wired Video Doorbell Pro, Wired Doorbell 2K Plus and Wired Doorbell 4K Pro: 16 to 24 VAC, 50/60Hz, 10VA to 40VA

Figures quoted from Ring's own hardwiring guidelines, read 2026-08-28. Manufacturers revise these; check yours before buying anything. If you run a different brand, find the equivalent page for it and use that instead. The mechanism described here is general; the numbers are not.

Why an old 10VA transformer is the usual culprit

A transformer sized for a chime is commonly 16 volts at 10VA. Read against the list above, that is under the minimum for every Pro-class doorbell and only just inside the range for a plain wired one.

It will often work at first. A doorbell that boots, connects and answers the app looks installed. What you cannot see is a component running near its limit for twenty-four hours a day, warming up, and ageing quickly.

A transformer that buzzes or hums audibly is telling you something. Some hum is normal in a laminated core, but a hum that appeared when the camera did, or one you can hear from another room, is worth a look.

When the fault is a short

Repeated failures with no load attached, a transformer that gets hot within minutes, or a breaker that trips all point the same way: a damaged cable somewhere between the transformer and the button.

Doorbell wire is thin, unshielded and frequently stapled through joists by somebody in a hurry. A staple through the insulation will not announce itself, and it can sit harmlessly for years until the wire shifts.

This is the point to stop and call an electrician. The low-voltage side is forgiving; the transformer is wired to the panel and that side is not. Finding a short in concealed wiring is not a job to learn on your own house.

Questions people ask

The chime went silent after the camera went in — the other half of the power problem
Is my chime mechanical or digital? — you need this before you change anything