How to choose the right IP and Ex rating for hazardous-area lighting

Three different questions

Buyers often read an Ex marking and an IP rating as a single quality score. They are not. Each answers a different question, and a luminaire can be excellent at one and useless at the other.

• IP (Ingress Protection) answers: can dust and water get inside? IP66 means dust-tight and protected against heavy seas. IP67 adds short immersion.
• Ex marking answers: can the luminaire ignite the atmosphere around it? Ex db IIC T6 Gb describes the protection type, the gas group, the temperature class and the zone.
• Zone answers: how often is an explosive atmosphere present? Zone 0 continuously, Zone 1 in normal operation, Zone 2 only in abnormal conditions.

Reading an Ex marking

Part	Meaning
Ex db	Flameproof enclosure — the housing contains an internal explosion
IIC	Gas group: acetylene and hydrogen (the most demanding group)
T6	Maximum surface temperature 85 °C — safe for the most ignitable gases
Gb	Suitable for Zone 1 (EPL Gb)

Practical rules

• If the area is Zone 1, the luminaire must be EPL Gb or better. A Zone 2 fitting is not enough.
• If the process handles acetylene or hydrogen, you need group IIC, not IIB.
• IP does not replace Ex. A non-Ex IP67 fitting is still illegal in Zone 1.
• Always check the ambient temperature rating against the hottest spot on your site, not the annual average.

When in doubt, send us the area classification drawing. We will match the luminaire to the zone, the gas group and the temperature class before we quote.