IP Ratings Explained: Why IP65 Is Your Best Friend (Even Indoors)

The silent killers of lighting fixtures are dust, haze, and humidity—not just rain.

In the specification sheets of modern lighting fixtures, one acronym stands out as a premium feature: IP65.

For the uninitiated, "IP" stands for Ingress Protection. To the average rental company or venue owner, an IP65 rating simply means "weatherproof." It is the box you check when you are doing an outdoor festival in monsoon season or lighting a bridge facade.

However, viewing IP ratings solely as "rain protection" is a rookie mistake. In reality, the most dangerous environment for a moving head fixture often isn't a rainy field; it is a nightclub, a theatre, or a dusty warehouse.

Decoding the Numbers

The IP system is not arbitrary. It is a two-digit code defined by international standard IEC 60529. Each digit represents a different form of defense.

The First Digit (Solids): Ranges from 0 (no protection) to 6 (dust-tight).
The Second Digit (Liquids): Ranges from 0 (no protection) to 9K (high-pressure steam jets).

Therefore, IP65 breaks down as:

6: Totally dust tight. No ingress of dust permitted.
5: Protected against low-pressure water jets from any direction.

The Real Enemy: The "Haze Sludge"

Why buy an IP65 fixture for an indoor arena? Because standard indoor fixtures (usually IP20) are essentially vacuum cleaners.

To keep their high-output LEDs or discharge lamps cool, IP20 fixtures use fans to pull massive amounts of air through the chassis. In a production environment, that air is filled with:

Haze & Fog Fluid: Sticky particulates that condense on internal parts.
Dust & Lint: From drapery, carpets, and general venue debris.
Confetti/Pyrotechnic Residue: Corrosive and extremely fine.

The Cycle of Destruction: When an IP20 fixture pulls this air in, the fog fluid acts as a glue, trapping the dust. Over just a few months, this forms a thick, insulating layer of "sludge" inside the head. This leads to overheating (shortening the LED engine life) and optical degradation (reducing brightness and sharpness).

The IP65 Solution: An IP65 fixture is a sealed ecosystem. The internal optics sit in a dust-free vacuum. You can run heavy haze every night, and the gobos will remain pristine because the air carrying the fluid never touches the internal glass.

Humidity and Corrosion

"Waterproof" does not just mean rainproof; it also implies resistance to ambient moisture.

In architectural applications, high humidity causes oxidation on the circuit boards (PCBs) and rust on the stepper motors of non-rated fixtures. Furthermore, fog fluid residue is often slightly acidic or conductive. A sealed IP65 chassis prevents this chemical interaction entirely, stopping short circuits before they happen.

The Economics of Maintenance

The primary argument against IP65 fixtures is weight and cost. However, the Total Cost of Ownership (TCO) is often lower:

Reduced Labor: An IP20 fixture requires a technician to open it up and clean lenses every few hundred hours. An IP65 fixture typically only requires a wipe-down of the external front lens.
Longevity: Internal components last longer because they aren't being "sandblasted" by dust or corroded by fluid.

Summary

When specifying a rig, stop thinking of IP65 as "the outdoor light." Think of it as "the low-maintenance light."

IP20: Open breathing. Sucks in dust, smoke, and grime. Requires frequent internal cleaning.
IP65: Hermetically sealed. Immune to dust, fog fluid, and humidity. Requires minimal maintenance.

If the venue uses haze, fog, or pyrotechnics, the air is hostile. Protect your investment by sealing it off.