AEMT - Association of Electrical and Mechanical Trades

26 October 2021
Understand ingress protection ratings
Mawdsleys BER, a specialist in the repair, rewind, refurbishment and supply of electric motors, generators and pumps, looks at ingress protection (IP) ratings, what they mean and how to understand a motor's IP rating.

IP or Ingress Protection refers to the degree of protection that enclosed equipment has from foreign objects and moisture. Usually found on the motor nameplate, this information is crucial when choosing an electric motor. It ensures that the enclosure can protect the motor from the environment it is operating in.

IP ratings are defined in standards set by the International Electrotechnical Commission (IEC), whereas The National Electrical Manufacturers Association (NEMA) uses an enclosure description of a similar standard.

The first digit of the IP rating, which goes from 0 to 6, refers to the protection the enclosure offers from solid foreign objects. The highest level of protection means that the motor is completely protected against dust.

As well as motor performance, this is a safety factor that can protect against accidental contact with the motor with tools, wires or parts of the body.

The second digit of the IP rating, which goes from 0 to 9, refers to the protection the enclosure offers from moisture. The highest level of protection here means that the motor is protected against high pressure and high-temperature jets of water.

As well as motors, IP ratings can be used to grade the resistance of an enclosure against dust and liquids for devices such as heating units, fans and power supply cases.


An IP rating is a combination of two numbers that indicate how well protected the enclosure is against water and foreign objects. The table below lists the protection rating at each level. So, a motor with a rating of IP55 would be protected against dust and water jets.


Equipment should protect against external influences that could negatively impact it, its users, or its environment, so the recommended IP rating of a motor will depend on these factors.

In the most demanding environments, which are potentially explosive – such as quarries, sewage treatment plants or oil rigs – a higher degree of protection will be required.

Failing to take these considerations into account and specify the correct IP rating can damage a motor or even cause complete failure, or worsestill, injury to personnel.

Therefore regardless of the application, it is essential to ensure that the IP rating offered by a motor considers the risk of impact from liquids and solid foreign objects. 

Solid foreign objects (first digit)

0 – No protection

1 – Protected against solid foreign objects of 50 mm and greater

2 – Protected against solid foreign objects of 12.5 mm and greater

3 – Protected against solid foreign objects of 2.5 mm and greater

4 – Protected against solid foreign objects of 1.0 mm and greater

5 – Dust-protected

6 – Dust-tight

Water (second digit)

0 – No protection

1 – Protected against vertically falling drops

2 – Protected against vertically falling water drops when the enclosure is tilted up to 15°

3 – Protected against spraying water

4 – Protected against splashing water

5 – Protected against water jets

6 – Protected against powerful jets

7 – Protected against the effects of temporary immersion in water

8 – Protected against the effects of continuous immersion in water

9 – Protected against high pressure and temperature water jets

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