Why “Washdown Rated” Must Be Defined Precisely
In food processing plants, car washes, and sanitation-heavy facilities, lighting failures are often caused by moisture ingress—not electrical defects. The term “washdown rated” is frequently misused, leading to premature fixture failure, contamination risk, and code violations.
Ingress Protection (IP) ratings provide measurable definitions for dust and water resistance. Understanding the differences between IP65, IP66, and IP69K is critical when specifying vapor tight lighting for high-pressure sanitation environments.
How IP Ratings Are Defined
IP ratings consist of two digits: one for solid ingress protection and one for liquid ingress protection.
| Digit | Meaning | Relevance |
|---|---|---|
| First digit | Protection against solids | Dust, debris |
| Second digit | Protection against liquids | Water exposure |
All three ratings discussed here are dust-tight (6). The difference is water exposure severity.
IP65 vs. IP66 vs. IP69K: Technical Comparison
| Rating | Water Exposure | Typical Use Case |
|---|---|---|
| IP65 | Low-pressure water jets | Damp industrial areas |
| IP66 | High-pressure water jets | Washdown zones |
| IP69K | High-pressure, high-temperature spray | Sanitation-critical areas |
IP69K is the only rating tested for high-temperature, close-range pressure washing.
Food Processing and Sanitation Requirements
Food plants routinely use hot water, detergents, and aggressive cleaning protocols.
- IP65 is insufficient for direct washdown
- IP66 may survive intermittent washdown
- IP69K is required for routine sanitation zones
| Area | Minimum Recommended Rating |
|---|---|
| Processing lines | IP69K |
| Packaging areas | IP66 |
| Cold storage | IP66 |
Sanitation zones require validation beyond marketing labels.
Car Wash and High-Pressure Spray Environments
Car wash tunnels expose fixtures to continuous high-pressure spray, chemicals, and vibration.
| Condition | Required Capability |
|---|---|
| Direct nozzle spray | IP69K |
| Chemical detergents | Sealed gaskets, corrosion resistance |
| Vibration | Secure mechanical fasteners |
IP66 fixtures often fail prematurely in tunnel installations.
Fixture Design Factors Beyond IP Rating
- Continuous silicone gaskets
- Compression-sealed end caps
- Stainless steel or reinforced polymer hardware
- Breather valves rated for washdown
An IP rating alone does not guarantee long-term survival without proper mechanical design.
Common Specification Errors in Washdown Lighting
- Specifying IP65 in sanitation zones
- Ignoring gasket material compatibility
- Using non-rated cable glands
- Assuming “vapor tight” equals washdown safe
Most washdown failures are predictable and avoidable.
Related Vapor Tight Lighting Categories
IP69K-rated fixtures are not optional in sanitation-critical environments. Understanding the limits of IP65 and IP66 prevents premature failure, contamination risk, and operational downtime.
Frequently Asked Questions
What is the Forward Throw of a Type III optic?
A Type III distribution is designed to push light forward and outward from the pole, typically in a batwing shape. It is engineered specifically for the perimeter. If you place a pole on the edge of a parking lot, a Type III optic ensures the light goes into the driving lanes and stalls, while minimizing the backlight that would otherwise spill onto a neighbor's property or into their windows.
When should I use a Type V symmetric optic?
Type V optics distribute light in an even, 360-degree circle around the pole. This is the ideal choice for interior poles—those located in the middle of a large parking lot surrounded by pavement. Because it is symmetric, it provides excellent uniformity and eliminates dark spots between poles. However, using a Type V on a perimeter pole is a primary cause of code violations, as 50% of the light will be directed behind the pole, often crossing the property line.
How do these distribution types impact Dark Sky compliance?
Dark Sky ordinances focus on reducing sky glow (uplight) and light trespass (spill).
- Type III: Easier to control near boundaries. When paired with a U0 (Zero Uplight) rating, it is the standard for perimeter compliance.
- Type V: While efficient for area coverage, it is harder to shield. In Dark Sky sensitive zones, Type V fixtures often require Internal House-Side Shields if they are located anywhere near the site boundary.
Can the wrong optic cause Glare complaints even if the light is on my property?
Yes. Glare is caused by high-angle light entering the eye at an uncomfortable level. A Type V fixture located near a property line might not put high foot-candles on the ground next door, but the luminous intensity (the brightness of the LED itself) can be visible from a neighbor's window. Type III optics are generally better at cutting off this high-angle light, keeping the source hidden from off-site view.
What is a House-Side Shield and do I need one?
A house-side shield is a physical barrier (internal or external) that blocks the light from traveling backwards. If you are forced to use a specific fixture that doesn't have a perfect Type III cutoff, or if your perimeter poles are extremely close to residential windows, a shield is your last line of defense. It chops the distribution pattern to ensure zero light crosses the property line, even if the optic's native throw would have allowed it.
Brandon Waldrop
As the lead technical specialist for our commercial lighting technical operations, Brandon Waldrop brings over 20 years of industry experience in product specification, outside sales, and industrial lighting applications.
His career began in physical lighting showrooms, where he focused on hands-on product performance and technical support. He later transitioned into commercial outside sales, working directly with architects, electrical contractors, and facility managers to translate complex lighting requirements into energy-efficient, code-compliant solutions.
Today, Brandon applies that industry experience to architect high-performance digital catalogs and technical content systems, helping commercial partners streamline the specification process and deploy lighting solutions with total technical confidence.