Will Your UK Bell Transformer and Chime Work With a Nest Doorbell?

• Nest Doorbell (battery): its built-in battery, or existing doorbell wires at 8–24 V AC, 50/60 Hz; the spec page says 10 VA and the compatibility table 10–40 VA
• Wired, the battery model still runs from its battery, which the bell wiring charges only to 80%; below 0 °C it cannot charge at all
• Nest Hello, also called Nest Doorbell (wired, 1st gen): Google's European figures are 10.8–30 V AC measured at most bell wires, or a 12–24 V AC transformer rated 8 VA or more

• Google says a no-contact voltage pen may not be sensitive enough, so the pro measures the bell wires with a multimeter
• On a transformer with 8, 12 and 24 V outputs, choosing a higher output does not raise its VA
• Chime wires not marked T, F and R are a case where Google says to call a local professional
• An intercom, gate control or remote doorbell is typically unsuitable for a Nest doorbell, Google says, so the battery model then runs on battery alone

• Nest Doorbell (battery), fitted wire-free: it cannot ring the home's chime, and Google recommends one of its speakers or displays to announce visitors
• Nest Doorbell (battery), wired: Google says mechanical and digital wired chimes usually work once the voltage checks out; it needs no chime connector, and the chime duration is set in the Nest app
• Nest Hello: uses Google's four-wire chime connector; the 2nd and 3rd gen connectors have two wires, and the Hello's is not compatible with them
• Google says a battery-only chime will not work with a Nest doorbell, and that fitting a new wired chime over battery-chime wiring is a job for a local professional installer

• Keep the Nest Doorbell (battery) on its battery and recharge it by USB, with no wiring at all
• Replace the transformer like-for-like on its existing supply, with a 12 V or 24 V model in place of an 8 V one: a replacement, so not notifiable in England
• Power a new transformer from a fused spur added to an existing circuit, away from a bathroom: an addition, also not notifiable
• A transformer wired to its own new way in the consumer unit is a new circuit: notifiable work for a registered electrician, outside a JACK booking
• Google's Indoor Power Adapter needs a hole through the outside wall, and one Google page lists it as US only while another says to buy it where available, so JACK does not promise it

• Google's spec page puts both at 16–24 V AC and 10–40 VA, so an 8 V British transformer is too low, and Google's transformer page says a blinking yellow light on the front means the doorbell is not getting enough power
• Both use Google's two-wire chime connector, which is not interchangeable with the Hello's four-wire one
• For the 2nd gen, Google says that in Europe and Australia a licensed electrician must install a new transformer first; that is Google's instruction, and England has no electrician licence
• A JACK pro fits one only on an existing transformer within that range, or after a like-for-like transformer swap on the same supply

• The transformer label, close enough to read volts and VA
• The chime, and whether it takes batteries
• The door frame where the doorbell goes, and where the router is, since the battery doorbell uses 2.4 GHz Wi-Fi only outside the US

A vetted pro prices your Nest job from the model and your photos, and the JACK app shows that fixed price before you book.

On heating, where the Heat Link goes moves the price most: a 3rd gen Heat Link in place of a programmer on the same wiring is the plainest job, while hot water on a cylinder, an S-plan or Y-plan wiring centre or an old wired thermostat to take out of the circuit adds to it. Anything that must be wired at the boiler itself is left out of the price and handed to a Gas Safe registered engineer.

On doorbells and cameras, power comes first: a battery doorbell or Nest Cam with a good 2.4 GHz signal is the lightest job, a weak bell transformer is swapped on its existing supply, and the Nest Cam with floodlight is priced as electrical work on your outside-light circuit. For a camera high on a gable, your pro can ask another pro on JACK to help through the Pro2Pro feature.

JACK does not sell devices, so the Nest kit is yours to buy. Accessories the job needs, such as a bell transformer, a fused spur or an outdoor junction box, are agreed and added at cost before you book, and so is parking where it has to be paid for. Several devices go on one booking for one fixed price. Prefer to pay for time? As a guide, hourly hire is typically £45–£95 per hour for smart home work and £55–£110 per hour for electrical work, and a full-day handyman booking is a flat £350–£400 for up to 8 hours on site.