A practical guide to Ingress Protection ratings for HVAC, BMS and electrical equipment.
When selecting electrical equipment for a Building Management System (BMS), HVAC installation or industrial application, one important specification to consider is the IP rating.
But what exactly does IP65 mean? Is IP66 better than IP55? And which rating should you choose for your installation?
In this guide, BMS Parts explains how IP ratings work, what protection they provide, and why choosing the right rating matters.
What Is an IP Rating?
IP stands for Ingress Protection, a classification system defined by the international standard IEC 60529 (also adopted as BS EN 60529).
An IP rating indicates how effectively an electrical enclosure protects against solid objects, dust, and water.
An IP rating normally consists of two numbers, for example, IP65.
- First digit (6): Protection against solid objects and dust.
- Second digit (5): Protection against water.
The higher the number within each category, the greater the specified level of protection.
First Digit – Protection Against Solids and Dust
| Rating | Protection |
|---|---|
| IP0X | No protection |
| IP1X | Objects 50 mm or larger |
| IP2X | Objects 12.5 mm or larger |
| IP3X | Objects 2.5 mm or larger |
| IP4X | Objects 1 mm or larger |
| IP5X | Dust-protected; limited ingress permitted |
| IP6X | Dust-tight; no dust ingress |
For example, an IP6X-rated device is dust-tight, making it suitable for environments where dust contamination could damage electrical components.
Second Digit – Protection Against Water
| Rating | Protection |
|---|---|
| IPX0 | No protection |
| IPX1 | Vertically falling water drops |
| IPX2 | Water drops with enclosure tilted up to 15° |
| IPX3 | Spraying water |
| IPX4 | Splashing water |
| IPX5 | Water jets |
| IPX6 | Powerful water jets |
| IPX7 | Temporary immersion in water |
| IPX8 | Continuous immersion under specified conditions |
| IPX9 | High-pressure, high-temperature water jets |
Important: Immersion ratings do not automatically guarantee protection against water jets. For example, IP67 equipment is not necessarily rated IP66.
Common IP Ratings Used in HVAC and BMS Installations
IP44 – Protection Against Small Objects and Splashing Water
IP44 equipment is protected against solid objects larger than or equal to 1 mm and splashing water.
Typical applications include suitably located electrical accessories, controls and equipment exposed to occasional splashing.
IP54 – Dust Protection and Splash Resistance
IP54 provides limited dust ingress protection and protection against splashing water.
It is commonly found on electrical enclosures, control equipment and HVAC components installed in relatively sheltered environments.
IP55 – Dust Protection and Water Jets
IP55 equipment is dust-protected and resistant to water jets.
Typical applications include:
- HVAC control enclosures
- Electric motors
- Pump equipment
- Plant-room electrical equipment
IP55 can be suitable where equipment may encounter dust, moisture or occasional cleaning with water jets, subject to installation conditions.
IP65 – Dust-Tight and Water-Jet Resistant
IP65 provides complete dust ingress protection and resistance to water jets.
Common applications include:
- Outdoor BMS sensor enclosures
- Electrical junction boxes
- HVAC control panels
- Weather-exposed equipment
- Industrial electrical installations
IP65 is often selected where protection from dust, rain and general weather exposure is required.
IP66 – Dust-Tight and Powerful Water-Jet Resistant
IP66 offers the same dust protection as IP65 but resists powerful water jets.
It suits more demanding environments, including exposed industrial equipment and installations subject to stronger water spray.
IP67 – Dust-Tight and Temporary Immersion Protection
IP67 equipment is dust-tight and protected against temporary immersion under specified test conditions, commonly up to 1 metre for 30 minutes.
Typical applications include specialist sensors, sealed electrical connectors and equipment where temporary flooding or immersion may occur.
IP67 does not mean equipment is suitable for indefinite underwater operation.
IP55 vs IP65 – What Is the Difference?
Both ratings provide protection against water jets, but their dust protection differs.
IP55: Dust-protected. Some dust may enter, as long as it does not interfere with satisfactory operation.
IP65: Dust-tight. No dust ingress is permitted under the specified test conditions.
For clean indoor plant rooms, IP55 may provide adequate protection. For dusty or exposed outdoor environments, IP65 may be more appropriate.
Choosing the Correct IP Rating for BMS Equipment
When selecting equipment, consider:
- Installation location: Is the equipment installed indoors or outdoors?
- Dust exposure: Is the environment clean, dusty or industrial?
- Water exposure: Could the equipment experience condensation, splashing, rain, washdown or flooding?
- Maintenance: Will the equipment be cleaned using water jets?
- Manufacturer requirements: Does the equipment have a specified mounting orientation or installation method?
Remember that an IP rating does not indicate resistance to corrosion, UV exposure, mechanical impact or extreme temperatures.
Outdoor installations may require additional protection, even when an enclosure has a high IP rating.
Why IP Ratings Matter in Building Management Systems
BMS equipment often operates in challenging environments, including rooftop plant areas, boiler rooms, ventilation systems and mechanical plant rooms.
Incorrect enclosure selection can lead to moisture ingress, corrosion, electrical faults, sensor failures, and unnecessary maintenance costs.
Choosing the right IP rating improves system reliability, equipment lifespan, and installation safety.
Conclusion
Understanding IP ratings helps engineers, installers and maintenance professionals select suitable electrical and HVAC equipment.
Whether specifying an IP55 motor, IP65 control enclosure, or IP67 sensor, the right rating depends on environmental conditions and the manufacturer's installation requirements.
Quick-reference comparison
| IP rating | Dust protection | Water protection |
|---|---|---|
| IP44 | Objects ≥1 mm | Splashing |
| IP54 | Dust-protected | Splashing |
| IP55 | Dust-protected | Water jets |
| IP65 | Dust-tight | Water jets |
| IP66 | Dust-tight | Powerful water jets |
| IP67 | Dust-tight | Temporary immersion |
| IP68 | Dust-tight | Continuous immersion under specified conditions |
At BMS Parts, we help engineers and installers source HVAC and building management components for their applications.
Visit www.bmsparts.co.uk to explore our range of BMS and HVAC products.
BMS Parts – Supporting Building Management and HVAC Engineers.
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