Posted on: 10 - 8 - 2021

How to understand IP Ratings Index for Lighting

What is IP Rating Index?

An IP rating index is shorthand for an Ingress Protection mark, sometimes referred to synonymously as an International (or Internal) Protection mark. An IP rating is usually a two-digit grading system that’s applied to the enclosure of a mechanical or electrical item (such as Energylight lighting solutions), giving clients a clear indication of the item’s resistance to various types of unwanted intrusion (such as dust or water).

‘Intrusion’ in the context of an IP rating has a threefold definition: IP codes signify the level of protection to users (hands, fingers etc) from mechanical or electrical parts; the degree of protection an enclosure offers those key components against dust, dirt and other damaging foreign bodies; and its overall resistance to moisture.

While you might encounter slight differences in IP ratings depending on where in the world you’re buying from, they are standardised in most regions: in New Zealand and Australia, IP codes are assigned in accordance with British standard BS EN 60529:1992. In Europe, they fall in line with IEC standard 60509:1989 and remaining international countries they conform to EN 60529 certification.

The IP Rating Index Chart

The IP ratings index chart below tells you what each digit in a standard IP code means. You can use this ingress protection chart to get a clear picture of the specific hazards and scenarios a given item’s electrical (or mechanical) components should be protected against, and to what extent in what sort of environments.


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What do the two digits in an IP Rating Index mean?

In general, an IP rating will consist of two digits, occasionally followed by a letter denoting specific materials, hazards or testing scenarios. The most common way you’ll see such a rating given will be in the format ‘IP43’, ‘IP67’, or similar. The higher the number the better the protection.

The first digit will be a number between 0-6 and indicates the degree of protection from ingress of solid objects (the user themselves, and other potentially harmful particulates such as dust or dirt).

The second digit in an IP rating will be a number between 0-9, denoting the quality of resistance to moisture ingress at varying intensities, angles, depths and pressures of exposure or immersion.

IP rating denotes three key metrics:

  • Resistance to ingress, accidental or otherwise, by the user
  • Resistance to ingress from foreign bodies (dust, dirt etc)
  • Resistance to moisture ingress
  • where 'x' in mentioned it is not tested for this


IP ratings for lights

IP ratings for lights are a key area of consideration in both residential and commercial design when planning/installing a lighting setup, particularly in bathrooms, industrial kitchen spaces, outdoor areas and any other spaces likely to be exposed to particulates or moisture ingress from various sources (including weather).


While lighting systems use the same IP rating numbers and definitions as any other enclosure, it’s also important to be aware of different ‘zones’ in each room or area, and how they might impact on the IP demands your lights need to meet. This is of particular concern in bathroom applications, as we’ll see below.


IP ratings for outdoor lights

IP rating for outdoor lights is key to both the safety and proper functioning of any unit installed where condensation, rain or wind-blown foreign bodies might pose a potential risk to circuitry and users alike. This includes accent lighting and soffit spots, safety or task floods, PIR/security sensor lights and more.


The following are general industry rules of thumb for outdoor lighting, but it’s always wise to seek manufacturer or supplier advice for your specific application scenario before installation:

  • IPX3 will protect against continuous spray at up to a 60° angle, which is generally considered sufficient in partially enclosed or covered areas.
  • IPX4 is more commonly used as a minimum in more exposed spaces.
  • IPX5 is needed if the lights are likely to be cleaned using pressurised jets, they should be rated at this or above.
  • IPX6 rated protection is extremely waterproof, impenetrable by weather, waterfalls, and even a non-sustained total soaking.
  • IPX7 rating (or higher) is needed for any lighting intended for immersion (e.g. pond or pool lighting) up to a depth of 1, but always check explicitly with the manufacturer before installing any lighting below the surface of the water.
  • IPX8 rating will be for immersion at greater depths, and these should again be checked explicitly for precise ingress resistance capabilities before installation.


A technical look at IP ratings and lighting

IP (Ingress Protection) ratings play an integral part in ensuring the quality, longevity and compliance of lighting projects are achieved per specification. 

To accurately predict the correct light level is being distributed until the application lifetime of a project, maintenance factors are applied to lighting design calculations. It is important to remember that not all luminaires are made equal and maintenance factors cannot simply be defaulted to 0.7 or 0.8. 

A Maintenance Factor is formulated based on the Luminaire Maintenance Factor, Lamp Lumen Maintenance Factor, Lamp Survival Factor and Room Surface Maintenance Factor. Maintenance Factor (MF) = LMF x LLMF x LSF x RSMF

This accounts for not only the lamp (LED) depreciation in light output overtime, but also the luminaire degradation due to the impact of dust and dirt ingress. Dirt on lamps and luminaires will generally cause the greatest light loss and it is not uncommon to encounter significantly reduced light output due to dirt build-up during long intervals between cleaning.

The higher the IP rating, the higher the maintenance factor will be. As maintenance factors significantly affect the number of luminaires needed to produce the specified illuminance, careful consideration should always be given to luminaire IP ratings.

Selecting a luminaire with a higher IP rating minimises initial and running costs and ensures lighting performance longevity.

For exterior applications in particular, consideration should also be given to enclosure/optical surfaces with smooth glass having a superior light output over time compared to exposed PMMA or PC Optics. This is due primarily to contaminants (dirt/spider webs) clinging to the exposed OPTICS. Glass also protects the OPTICS from contaminants such as jet engine exhaust fumes on Aprons. 


IP ratings offer buyers, installers, and users a convenient and universally consistent way to assess the likely performance of a wide range of enclosures in many typical applications and environments. If you’re in any doubt as to what IP rating you need for the specific use you have in mind, then please don’t hesitate to contact Energylight:


(Resources: rs-components; rainford solutions, lighting style)

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