Most UK houses are on a single-phase supply, and a couple of small 230 V splits is a normal domestic request for an electrician to check. A whole-house bank of indoor units can be more than the cut-out and the service cable were meant to carry. That question goes to a competent electrician and, where the supply itself is the limit, to the distribution network operator. This page does not set an amp ceiling. The refrigerant work remains an F-gas install, and outdoor siting in England follows the Planning Portal.
230 V houses and a couple of wall units
Single phase at 230 V is the ordinary house supply. Domestic splits are built for it. One bedroom unit, or a bedroom and a lounge, is everyday work once the consumer unit has a lawful way to feed them and the cables are sized for the run. The installer and the electrician should agree the circuit. A reel and an adaptor are not the method.
Three phase exists in some houses and in many commercial buildings. Do not assume you need it for two small wall units. Do not assume you have it because a sales page mentioned a large outdoor unit. Most UK homes are single phase. Confirm the board before you order.
Service head, other loads and a price that is not firm
The limit is the service head, the cable in the street, and what else is already on: an immersion, a cooker, an electric vehicle charger, an existing heat pump. Adding a condenser in every room can trip or overheat a supply that was fine for lights and a kettle. The person who can see the cut-out and the board is the electrician. If they say the supply must change, that change is for the distribution network operator, not a guess in a brochure.
Because supplies differ, a single number of amps would be false. Anyone who offers you a universal ceiling without looking at the board is inventing it. Refuse that shortcut and get the board looked at. Do not open sealed parts to take the photo yourself.
A quote can list model codes, cooling and heating kW, and a provisional electrical allowance. It should say the price is not firm until the supply is confirmed, if the job is more than a straightforward one or two units. Running all indoors flat out on the design day is the case to mention, not only the summer bedroom at night. A multi-split is still one electrical load, sometimes a large one. It can be easier than several outdoor units. It does not skip the electrician's check.
The board visit the brochure cannot skip
F-gas certification does not cover the consumer unit. Electrical work needs a competent person. Planning Portal conditions in England still apply to each outdoor unit you add. This page will not give an amp number.
Frequently asked questions
Are UK homes single phase?
Most are. Domestic wall splits are 230 V single-phase machines. A couple of small units is a normal enquiry. Confirm the board before you order.
How many amps can I add?
This page will not give a number. The electrician and, if needed, the distribution network operator have to see your supply. A universal amp ceiling would be made up.
Does a multi-split avoid a supply upgrade?
It is still one electrical load, sometimes a large one. It can be easier than several outdoor units. It does not skip the electrician's check.
Can the equipment be ordered before the board is seen?
Ask the electrician before the equipment order is firm. A whole-house set may need the distribution network operator. A couple of small splits is a normal single-phase enquiry, not a reason to invent an amp ceiling.
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How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.