IP65 and IP66 are quoted interchangeably in tenders, and both get shortened to “waterproof” in the meeting. They are not the same promise. One is protected against jets, the other against powerful jets, and neither one says anything about the gland, the connector or the way the fixture was mounted — which is where most outdoor failures actually happen.
1. What the two digits mean
The first digit is solids, the second is liquids. Stage lighting lives almost entirely in three combinations plus one that matters for coastal work.
| Rating | Solids | Liquids | In practice |
|---|---|---|---|
| IP20 | Fingers and objects over 12 mm | None | Indoor stages, studios, theatres. Dust will get in; that is accepted. |
| IP44 | Objects over 1 mm | Splashing water | Covered terraces and humid rooms. Not for rain. |
| IP65 | Dust tight | Water jets from any direction | Rain-exposed and permanent outdoor installs. |
| IP66 | Dust tight | Powerful jets, e.g. sea spray, pressure washing | Coastal, washdown areas, exposed facades. |
“Dust tight” is the important difference between IP44 and IP65. A fixture that lets dust in loses output on the lens and eventually cooks its fans; a dust-tight fixture keeps its optical path clear for years.
2. Where each rating belongs
| Venue / position | Sensible rating | Why |
|---|---|---|
| Theatre, studio, indoor stage | IP20 | No water load; prioritise noise and optics instead |
| Covered outdoor stage, open-sided tent | IP44 minimum, IP65 if wind-driven rain reaches the truss | Roofs do not stop horizontal rain |
| Festival main stage | IP65 | Rain, mud and pressure from the audience side |
| Facade, park, night-tour install | IP65, IP66 near the coast | Permanent exposure plus salt or washdown |
3. The rating protects the fixture, not the installation
This is where most outdoor rigs fail, and it is not the fixture's fault:
- Cable glands and connectors. An IP65 fixture with an unsealed connector is an IP20 fixture. Use the supplied glands, torque them, and orient them downward.
- Drain loops. Water runs along a cable. A drip loop before the connector stops it entering the housing.
- Orientation. A fixture mounted lens-up collects water in the lens recess; the same fixture lens-down or lens-forward does not.
- Unused ports. Every blanking cap that is left off is a hole in the rating.
- Pressure washing. IP65 tolerates jets; it does not tolerate a 100 bar washer at 10 cm. IP66 exists for that reason.
4. What an IP rating does not cover
- Corrosion. IP says nothing about salt fog or the paint system. Coastal installs need a corrosion specification separately.
- UV ageing. Seals and plastics degrade in sunlight; ask what the gasket material is.
- Condensation. A sealed fixture that heats and cools in humid air pulls moisture in through breathing paths. A breather valve is a real design feature, not a gimmick.
- Thermal cycling. Ten years of expansion and contraction loosens what a lab test never touched.
- The cable itself. Ordinary rubber cable cracks in two seasons outdoors. Specify the jacket.
5. Coastal and permanent installs
Salt is the difference between “outdoor” and “coastal outdoor”. Within a few hundred metres of the sea, salt deposits on the lens, works into the seals and accelerates corrosion on every fastener. Two practical rules: choose IP66 rather than IP65 where spray is plausible, and put the fixture on a maintenance schedule instead of waiting for a failure. Stainless fasteners and a proper breather matter more than another 100 W of output.
6. Maintenance: what to check, how often
| Check | Interval (outdoor install) | Why |
|---|---|---|
| Glands and connectors | Every service visit | Loose glands are the number one water path |
| Seals and gaskets | Every 6–12 months | Rubber takes a set and stops sealing |
| Lens and front glass | Every 3 months, coastal monthly | Salt and dust cut output before they cause failure |
| Drainage paths | Before rainy season | Blocked drainage turns a sealed housing into a bucket |
| Fasteners and brackets | Every 12 months | Vibration plus corrosion equals a dropped fixture |
7. Questions worth asking a supplier
- Is the IP rating for the fixture as shipped, or for the fixture with the supplied glands fitted?
- What is the gasket material, and what is its expected service life outdoors?
- Does the housing have a breather valve, and is it replaceable?
- Which fasteners are stainless?
- What is the recommended service interval for a coastal install?
An IP rating is a starting point for a conversation about the installation, not a guarantee about the weather. The fixtures that survive ten winters are the ones specified with the mounting and the maintenance in mind.
8. How the test is actually run
The liquid test for the “5” digit is a 6.3 mm nozzle at 12.5 litres per minute from any direction, for at least three minutes. The “6” digit uses a 12.5 mm nozzle at 100 litres per minute — roughly eight times the water — also from any direction. Both are short, controlled exposures on a sample, at ambient temperature, with the fixture as supplied. None of that is the same as a two-week festival in horizontal rain, which is why the installation details in section 3 matter more than the number on the box.
9. A spec line you can paste into a tender
“Outdoor fixtures shall be minimum IP65 (dust tight, protected against water jets), with IP66 specified for coastal or washdown locations. Glands, blanking caps and connectors shall be supplied and rated to the same class as the fixture. Fixtures shall include a replaceable breather valve and stainless fasteners. Mounting orientation and drainage shall be documented in the installation drawing.”
That paragraph does more for a ten-year outdoor install than any single datasheet number, because it makes the accessories part of the specification instead of an afterthought.
Specifying an outdoor install? Tell us the exposure — covered stage, open festival, facade, coastal — and we will point you at the right IP class and the accessories that keep it sealed.