Three-Phase Power for Kent Businesses: Do You Need It and How to Get It

The vast majority of homes and small businesses in the UK are supplied with single-phase electricity — a 230V supply delivered via a live, neutral, and earth conductor. For most purposes this is perfectly adequate: it can power lighting, heating, computers, and most commercial equipment without difficulty. But as businesses grow, install larger machinery, or take on high-demand processes, single-phase power can become a limiting factor. Three-phase power delivers three times the capacity of a single-phase supply at the same voltage, and it is the standard supply for industrial premises, large commercial buildings, and any site with significant motor-driven equipment.

This guide explains what three-phase power is, how to tell whether your business needs it, what is involved in upgrading from single-phase to three-phase, and what it costs across Kent in 2026.

What Is Three-Phase Power?

A three-phase supply delivers three separate alternating current (AC) waveforms, each offset by 120 degrees from the others. In a standard UK three-phase supply, each phase delivers 230V between the phase conductor and neutral, and 400V between any two phase conductors. This means a three-phase supply can deliver up to three times the power of a single-phase supply using conductors of the same size, which is why it is the standard for high-power applications.

Three-phase motors are also more efficient and smoother-running than single-phase motors of equivalent power, because the three offset waveforms produce a rotating magnetic field that drives the motor continuously rather than in pulses. This is why three-phase power is standard for compressors, CNC machines, lifts, large HVAC systems, and other motor-driven equipment.

Do You Need Three-Phase Power?

The most common triggers for a three-phase upgrade in Kent businesses are: installing equipment that requires a three-phase supply (such as a large compressor, a commercial oven, or a CNC machine); reaching the capacity limit of the existing single-phase supply (typically 100A, equivalent to about 23 kW); installing multiple EV chargers; or connecting a large solar PV system with battery storage. The following table summarises the typical demand levels that indicate a three-phase supply may be needed.

How to Get a Three-Phase Supply

Getting a three-phase supply involves two distinct elements: the network connection (provided by your Distribution Network Operator, or DNO) and the internal electrical installation (carried out by a qualified electrician). The DNO for most of Kent is UK Power Networks. They are responsible for bringing the three-phase supply to your premises — either by upgrading an existing single-phase connection or by installing a new service cable from the nearest three-phase distribution point.

The process typically works as follows: your electrician assesses your demand requirements and specifies the supply capacity needed; you (or your electrician on your behalf) apply to UK Power Networks for a new or upgraded connection; UK Power Networks quotes for the network reinforcement work and installs the new service cable and meter; your electrician then installs or upgrades the internal distribution board and wiring to make use of the new supply. The network connection and the internal installation are separate contracts, and both must be completed before the new supply can be energised.

Three-Phase Upgrade Costs in Kent: 2026 Guide

The cost of a three-phase upgrade has two components: the DNO connection charge (paid to UK Power Networks) and the internal electrical installation cost (paid to your electrician). The DNO charge varies significantly depending on how far the nearest three-phase network point is from your premises and what reinforcement work is required. The internal installation cost depends on the size of the new distribution board, the number of circuits to be upgraded, and the length of the cable runs.

All commercial electrical work is subject to 20% VAT. The total cost of a three-phase upgrade for a typical commercial unit in Kent — including the DNO connection and a new 100A distribution board — is typically £4,000–£12,000 plus VAT, depending on the network connection complexity. For industrial premises with high demand or remote network infrastructure, costs can be considerably higher.

Balancing Three-Phase Loads

One of the most important considerations when designing a three-phase installation is load balancing — distributing the electrical loads as evenly as possible across the three phases. An unbalanced three-phase supply (where one phase carries significantly more load than the others) is less efficient, can cause voltage fluctuations, and may result in additional charges from your energy supplier. A qualified electrician will design the distribution board to balance the loads at the design stage, and will advise on how to connect new equipment to maintain balance as the installation evolves.

Areas Covered

Kent Trade Solutions designs and installs three-phase electrical systems for commercial and industrial premises across Sittingbourne, Faversham, Maidstone, Canterbury, Ashford, Folkestone, Thanet, Medway, the Isle of Sheppey, and the wider Kent area. We can liaise with UK Power Networks on your behalf and manage the entire upgrade process from initial assessment to final certification.