What fuse rating does a Quooker or boiling water tap need?

A 13 A BS 1362 fuse in a switched fused connection unit is what every mainstream UK boiling water tap manufacturer (Quooker, Fohen, Qettle, InSinkErator) specifies. A smaller fuse (3 A or 5 A) can nuisance-trip on the cold-fill inrush and can invalidate the manufacturer's warranty.

Can a boiling water tap share a socket with a dishwasher?

No. The manufacturers all specify a dedicated switched fused connection unit for the tap tank, so it can be isolated locally without pulling the sink cabinet apart. Sharing a socket with a dishwasher or waste disposal is not compliant with the fitting instructions.

Does the FCU have to be above the worktop?

Yes, the switch must be accessible without opening the sink cabinet. Regulation 462 of BS 7671 requires a means of isolation that is reachable during a fault. A switched FCU above the worktop, within about 2 metres of the tap, satisfies this and is what every manufacturer's fitting instructions show.

Is a new circuit for a boiling water tap notifiable under Part P?

Spurring off an existing socket to feed a fused connection unit is not notifiable. Running a brand new circuit from the consumer unit is notifiable under Part P in England and needs either a Part P registered electrician or a building notice to the local authority.

Does the tap need RCD protection?

Yes. The kitchen socket circuit that the spur is taken from must already be RCD-protected under BS 7671 (a 30 mA RCD or RCBO). The tap sits under a wet appliance, so RCD protection is not optional.

How to Wire a Boiling Water Tap Electrical Supply (UK)

Helpful video reference. An installer's UK tutorial "Boiling water tap install! (Quooker fusion tap)" shows the Quooker tank going in under a UK kitchen sink. Worth watching before you plan the cable route so you can see how the tank sits, where the flex enters, and how much space the sink base cabinet loses to the tank body.

Before you start. Isolate the kitchen ring final circuit at the consumer unit and confirm dead with an approved voltage tester at the socket you plan to spur from. If the kitchen sockets are still on an older split-load board without RCD or RCBO protection, the whole kitchen circuit needs sorting first: a boiling water tap under a sink is not the place to compromise on 30 mA earth-fault protection.

1. Read the tank data plate first

Every boiling water tap uses a small insulated tank under the sink to keep water at about 108 °C under pressure. The tank plugs into a flex, and the flex enters a switched fused connection unit above the worktop. Before you buy anything, take the fitting instructions and note the tank wattage: Quooker's Pro3 sits around 2.4 kW, Fohen and Qettle broadly the same, InSinkErator similar. All of them are within a 13 A fused connection unit's rating with plenty of headroom.

2. Pick where the switched FCU goes

The switched FCU is the local isolator. It has to be reachable without opening the sink cabinet, so the homeowner can switch off if the tank ever leaks or needs draining. The usual place is on the tile splashback above the worktop, at socket-outlet height, no further than about 2 metres from the tap.

Do not put the FCU inside the sink cabinet. If the tank ever weeps, the water finds the FCU and you have created the fault you were trying to isolate for.

3. Spur off the ring final circuit

Take a 2.5 mm² twin-and-earth spur from the nearest kitchen ring socket. Only one unfused spur is permitted per socket on a ring final circuit under BS 7671, so pick a socket that has not already been spurred (an easy check: pop the faceplate and count the cables in the back box).

The spur cable feeds the supply (line) terminals of the FCU. Sleeve the earth conductor in green-and-yellow sleeving before it enters the terminal. Tighten to the manufacturer's torque setting (usually 1.2 to 2.0 Nm on a modern MK or Crabtree plate).

4. Drop into the sink cabinet

From the load (out) side of the FCU, run a length of 1.5 mm² 3-core heat-resistant flex down inside the wall (or through a hole in the worktop upstand) into the sink base cabinet. Keep the flex clipped, not hanging loose, and leave enough slack that the tank can be pulled forward for service.

Terminate the flex into the manufacturer's flying lead or terminal box. Most Quooker units are supplied with a pre-fitted 3-pin plug on the tank end, so many installers fit an unfused single socket inside the cabinet fed from the FCU and simply plug the tank in. Either approach is acceptable if the FCU above the worktop remains the accessible isolator.

5. Fit a 13 A fuse, not a 3 A

Fit a 13 A BS 1362 fuse in the FCU. This is the one point that catches installers out: a 3 A or 5 A fuse looks tidier for a small load, but the tank's cold-fill inrush current can trip a small fuse and, more importantly, every manufacturer's fitting instructions specify 13 A. Fit anything else and you can void the warranty on the tank.

Label the FCU faceplate ("Boiling water tap") with a printed circuit label so the next person to look at the kitchen knows what it isolates.

6. Test, energise, certify

With the circuit dead: continuity of ring (r1, rn, r2), insulation resistance between conductors, and polarity at the FCU. Energise, then check earth fault loop impedance (Zs) at the FCU load side and confirm the RCD or RCBO trips in under 40 ms at ×5 trip current.

Issue a Minor Works Certificate (for a spur off an existing circuit) or a full Electrical Installation Certificate (if the tap has been fed from a brand new dedicated circuit). Give a copy to the homeowner and keep one for the file.

Stop and call an electrician if: the kitchen ring is not RCD protected, the socket you planned to spur off already has a spur, the sink cabinet has no room for the tank plus the flex loop, or you find aluminium conductors in the ring (an older 1970s installation). Any of those and you need a proper look at the kitchen circuit before adding load to it.

When to call us

The plumber can do the water side, but the electrical connection needs to be right. Richard fits and certifies boiling water tap supplies for Quooker, Fohen, Qettle and InSinkErator taps across Sandwich and east Kent, including the switched FCU, the spur into the cabinet and the Minor Works Certificate for your records and the manufacturer's warranty.

Fitting a boiling water tap in Sandwich or east Kent?

Richard wires and certifies the electrical supply so your plumber can commission the tap the same day. Part P registered, fully insured.

Contact Richard

How to wire a boiling water tap electrical supply