By Thomas Parker, UK & Ireland Sales Manager, Brown GearTech
Most three-phase motors sold in Great Britain from 0.75kW to 1000kW must meet IE3. Standard 2, 4 and 6-pole motors from 75kW to 200kW must meet IE4. Smaller three-phase motors from 0.12kW up to 0.75kW must meet IE2, and so must the variable speed drives that run motors from 0.12kW to 1000kW. Which class your machine needs depends on the motor’s rating, pole count, duty and whether it is a brake or hazardous-area design.
This is one of the questions OEMs ask us most often, usually when a motor list is being reviewed for a new machine or a supplier has changed a datasheet. Here is how the rules work, what is exempt and what to plan for.
Where do UK motor efficiency rules come from?
In Great Britain, minimum energy performance standards (MEPS) for motors are set by the Ecodesign for Energy-Related Products and Energy Information Regulations 2021. Schedule 16 of those regulations carries over the EU ecodesign regulation for motors and drives, (EU) 2019/1781, which still applies directly in Northern Ireland.
The efficiency classes themselves are defined in IEC 60034-30-1. IE1 is standard efficiency, IE2 high efficiency, IE3 premium efficiency and IE4 super premium efficiency. IE5, ultra premium efficiency, is defined but not yet required by law. Each class sets a minimum efficiency for every rating and pole count, and a motor’s efficiency rating should be shown on its nameplate.
The rules apply when a motor is placed on the market. That covers a motor you buy as a component and a motor built into a machine you sell. Motors already installed and running do not have to be replaced.
Which efficiency class does my motor need?
| Motor | Pole | Min. class | From |
| Three-phase, 0.12kW to under 0.75kW | 2, 4, 6, 8 | IE2 | 1 July 2021 |
| Three-phase, 0.75kW to 1000kW | 2, 4, 6, 8 | IE3 | 1 July 2021 |
| Three-phase, 75kW to 200kW | 2, 4, 6 | IE4 | 1 July 2023 |
| Brake motors and explosion-protected (ATEX) motors other than Ex eb, 0.75kW to 1000kW | 2, 4, 6, 8 | IE3 | 1 July 2023 |
| Ex eb increased safety motors, 0.12kW to 1000kW | 2, 4, 6, 8 | IE2 | 1 July 2023 |
| Single-phase motors, 0.12kW and above | All | IE2 | 1 July 2023 |
| Variable speed drives for motors of 0.12kW to 1000kW | Not applicable | IE2 | 1 July 2021 |
The rules cover motors rated from 50V to 1000V for continuous duty, meaning S1, or S3 and S6 with a duty factor of 80% or more.
What is the difference between IE3 and IE4?
An IE4 motor wastes roughly a fifth less energy than an IE3 motor of the same rating. Manufacturers get there with more active material, better electrical steel or different motor technologies, such as permanent magnet designs. That can make an IE4 motor longer or heavier than its IE3 equivalent, so check the dimensions before treating it as a drop-in swap. Higher-efficiency motors can also draw a higher starting current, so check that starters and circuit protection are rated for it.
The difference looks small on a datasheet. Over thousands of running hours, it adds up.
| Example | IE3 min. | IE4 min. | Power saved | Saving per year |
| 15kW 4-pole, 4,000 hours a year | 92.1% | 93.9% | 0.31kW | around £310 |
| 90kW 4-pole, 6,000 hours a year | 95.2% | 96.1% | 0.89kW | around £1,340 |
Figures use the minimum efficiencies in IEC 60034-30-1 at full load and an illustrative tariff of 25p/kWh. Your own figures depend on load, tariff and duty.
For a motor running a few minutes a day, IE3 is usually the sensible choice. For continuous-duty drives on pumps, fans, conveyors and process lines, IE4 is often worth specifying even where the law does not require it.
Are any motors exempt?
Yes. The main exemptions include:
- Motors for intermittent duty below an 80% duty factor
- Motors completely integrated into a product, such as a pump or fan, where they cannot be tested on their own
- Motors fully integrated with a drive that cannot be tested separately
- Motors built for ambient temperatures above 60°C or below -30°C
- Pole-changing (multi-speed) motors
- Motors designed to run wholly immersed in a liquid
There is also an exemption for motors placed on the market before 1 July 2029 as substitutes for identical motors in products already on the market. The conditions are specific, including dates and marking requirements, so check them carefully before building a spares strategy around them. After that date, replacement motors need to meet the current rules.
Does the drive or inverter need to comply too?
Yes. Variable speed drives, often called inverters, for motors from 0.12kW to 1000kW must meet IE2 as defined for drives in IEC 61800-9-2. The older option of fitting an IE2 motor with a drive instead of an IE3 motor ended on 1 July 2021. A compliant motor on a non-compliant drive still leaves your machine short of the rules.
It is also worth looking at the whole system. A drive that matches motor speed to the load will often save more energy than moving up a motor class.
Will the motor efficiency rules changes after 2026?
Very likely. The European Commission launched a review of the motor and drive ecodesign rules in August 2025, with the aim of adopting new rules in 2029. The review is also looking at material efficiency and circular economy requirements, not just energy use.
The UK has historically mirrored these changes. In October 2026 the Department for Energy Security and Net Zero opened consultations to align Great Britain’s rules for industrial fans and standby power with newer EU standards. OEMs designing machines today should expect motor requirements to tighten over the working life of the machine.
What should OEMs do now?
- Design around standard IEC frame sizes, so a higher-efficiency motor still fits when requirements change
- Check whether your motors run from a drive, because the drive has its own requirements
- Ask for the efficiency class on every datasheet, not just the catalogue page
- Consider IE4 on high-hour drives where the energy saving pays back quickly
- Review your spares strategy before 2029, especially if you rely on identical replacement motors
We have seen the cost of getting this wrong. One customer had built a test rig around a non-standard 15kW motor footprint, and every replacement became a hunt for a part that should not exist. Moving to the standard IEC frame solved it for good.
Frequently Asked Questions
Is IE4 mandatory in the UK?
Only for some motors. IE4 is mandatory for standard three-phase 2, 4 and 6-pole motors from 75kW to 200kW, from 1 July 2023. Most other three-phase motors from 0.75kW to 1000kW must meet IE3.
Is a 15kW motor IE3 or IE4?
A standard three-phase 15kW motor must be at least IE3. IE4 is only required from 75kW to 200kW. An IE4 15kW 4-pole motor still saves energy, at a minimum of 93.9% efficiency against 92.1% for IE3, so it can pay back on long-running drives.
Does a 90kW motor need to be IE4?
Yes, if it is a standard three-phase 2, 4 or 6-pole motor. An 8-pole, brake or explosion-protected 90kW motor needs IE3 instead.
Do single-phase motors need to be IE3?
No. Single-phase motors of 0.12kW and above must meet IE2, a requirement that has applied since 1 July 2023.
What is the difference between IE3 and IE4 motors?
IE4 is a higher efficiency class than IE3. An IE4 motor wastes roughly a fifth less energy than an IE3 motor of the same rating, which matters most on drives that run for long hours.
Can I still buy IE2 motors in the UK?
Only in specific cases. IE2 is the minimum for three-phase motors from 0.12kW up to 0.75kW, single-phase motors from 0.12kW, and Ex eb increased safety motors. Most three-phase motors of 0.75kW and above must be at least IE3.
Can I still use an IE2 motor with a variable speed drive instead of IE3?
No, not for new motors. The option of using an IE2 motor with a variable speed drive in place of an IE3 motor ended on 1 July 2021. Motors in the IE3 range must now meet IE3 whether or not they run from a drive.
Do I need to replace my existing IE2 motors?
No. The efficiency rules apply when a motor is placed on the market, not to motors already installed and running. When an existing motor fails, any new replacement must meet the current rules unless an exemption applies.
Do IE3 and IE4 motors have a higher starting current?
They can. Higher-efficiency motors often have higher inrush and starting currents than older IE1 and IE2 designs. Check that contactors, starters and circuit breakers are rated for the new motor, especially on direct-on-line starts.
Do brake motors and ATEX motors need to be IE4?
No. Brake motors are excluded from the IE4 requirement and must meet IE3 from 0.75kW to 1000kW. The same applies to explosion-protected (ATEX) motors other than Ex eb types. Ex eb increased safety motors must meet IE2.
Do variable speed drives have an efficiency requirement?
Yes. Variable speed drives for motors from 0.12kW to 1000kW must meet the IE2 class for drives, defined in IEC 61800-9-2. This has applied in Great Britain since 1 July 2021.
Can I replace an old motor with an identical one?
Sometimes, until 1 July 2029. Motors placed on the market before that date as substitutes for identical motors in existing products are exempt, but the conditions are specific. After that date, replacement motors need to meet the current efficiency rules.
Do the same rules apply in Northern Ireland?
Yes, in practice. Northern Ireland follows EU Regulation (EU) 2019/1781 directly, while Great Britain applies the same requirements through the Ecodesign for Energy-Related Products and Energy Information Regulations 2021.
Will IE5 motors become mandatory?
Not yet. No IE5 requirement has been set in the UK or EU. The European Commission is reviewing the motor rules, with new requirements due to be adopted in 2029, and the UK has historically followed EU changes.
SPEAK TO OUR TEAM TODAY
If you’d like tailored advice on gearbox specification, speak to our engineering team today.
