NEMA and IP ratings are two systems that define the levels of safety and environmental protection provided by an enclosure. The enclosures themselves are usually fabricated from steel or durable plastic, but they need an opening for assembly or access to the equipment inside. That opening is sealed with a gasket, which is key to how the enclosure is rated.
NEMA vs IP Rating: Different standards, same goal
NEMA ratings define enclosure protection in terms of the environment. IP ratings, (the system used in Europe and elsewhere,) define ingress protection (hence “IP”) in terms of solid objects and liquids. These systems overlap and the most widely used ratings are as follows:
- NEMA 2 (Indoor use, protects against vertical drops) – broadly equivalent to IP11
- NEMA 3 (Outdoor use, protects against rain and snow) – comparable to IP54
- NEMA 4 (Protection against hose-directed water) – IP50
- NEMA 6 (Temporary immersion at limited depth) – IP67
Gasket Implications
The two factors to consider are the cutting method and material. A gasket cut from strip has joins, and that creates potential leak paths. A gasket cut by die, laser or waterjet has no such joins and so provides better protection.
The gasket material must be compressible to seal completely all around the opening. (Hinges and clamps sometimes create gaps that vary widely.) If the enclosure will be opened frequently the material should also resist taking a compression set. Cellular gasket materials are a popular choice, but a closed-cell structure is essential to prevent water penetration.
When selecting any gasket material, it’s important to consider the environment. Those used outdoors could suffer UV exposure and wide temperature swings. Gaskets used near high voltage electrical equipment need good ozone resistance. Flammability may also be a concern.
NEMA an IP Rated Gasket Material
Closed-cell silicone foam is often used for enclosure gaskets due to its low compression set and wide temperature range. EPDM can be a cost-effective alternative and has good UV resistance, but depending on the environment and protection needed there may be other options. To explore the range of gasket materials appropriate to your application, speak with a Hennig Gasket product specialist.
