CAB Electrical ServicesNAPIT registered electrician, Wirral
Call Carl, Mon–Fri 8:30–607738 558186 Get a free quote

Thermostats and underfloor heating

What different heating means for your electrics. Some heating needs its own protected circuit and some doesn't. Here's which is which, and what a heated floor needs from your fuse board.

Gets its own breakerElectric underfloor heating · Heat pumps · Immersion heaters
Doesn't need a new oneSmart thermostats · Water underfloor heating · Single towel rails (fused spur)

The electrics, not the heating itself. Your flooring or heating installer lays the mat or pipes. Carl provides the dedicated circuit and breaker, the thermostat's supply and connection, and the testing and certification.

See whyPlan the supplyAsk about the electrics

Does it need its own breaker?

Pick a type of heating to see how it connects to your fuse board.

Consumer unit LightsSocketsShowerBoilerHeatingSpare 21°Smart thermostat Boiler 24° Heating mat under the tiles Manifold, pump and valves Heat pumpIsolator SPUR Heated towel rail Double-pole switch Hot water cylinder
Needs its own breaker?

Protection
Typical cable

    Plan the supply for underfloor heating

    Take the floor area and heat output from your heating installer's spec, and see the load, the breaker and cable it needs, and what it costs to run.

    21° ThermostatFloor sensor Floor 18°

    Heat output

    0 kW0 A
    16 ARCBO on its own circuit
    2.5 mm²Typical cable
    £0a day, at full power

    Related

    Try itSmart controlsHeating on your phone, tied into scenes like Good night and Away.Try a smart roomTry itFuse board upgradesSpace for the extra circuit, with RCBO protection.See fuse boardsTry itBathroomsThe rules for heating and towel rails around water.Bathroom zonesTry itRenovationsGet the circuit in before the floor goes down.See the timelineHeat pumps and ACThe dedicated supply they need.Air conditioning power

    Good to know

    Does underfloor heating need its own breaker?

    Electric underfloor heating normally has its own circuit with 30 mA RCD protection, usually an RCBO, sized to the load. Water underfloor heating doesn't, because the heat comes from the boiler or heat pump.

    Does a smart thermostat need a new circuit?

    No. It's a control that joins your boiler's existing supply and heating controls. Some models need an extra wiring centre or a neutral at the wall.

    Which floors can be heated?

    That's one for your flooring or heating installer and the floor maker's limits. As a guide, tile and stone work best, while wood, laminate and vinyl need a heating-approved product with a floor temperature limit. The electrical supply is the same either way.

    Why is it tested before the floor goes down?

    A nail or trowel through a heating cable is very hard to fix once the floor is laid. So whoever lays the heating tests it before, during and after the floor goes down, and Carl tests the circuit again when he connects it.

    Does insulation matter?

    Yes. Insulation boards under the heating send the heat up into the room instead of down, so the floor warms faster and costs less to run.

    New circuit? A new circuit is notifiable under Part P, and we test and certify where appropriate. If your fuse board has no spare ways, we can upgrade it first. See fuse boards.

    Tell Carl what you need

    Free, no-obligation quotes across the Wirral. Most enquiries get a reply the same working day.

    Get a free quote WhatsApp