NEMA Ratings Guide for Enclosures
What are NEMA Ratings?
NEMA (National Electrical Manufacturers Association) defines the types of environments in which an electrical enclosure can be used. The rating ensures protection of equipment inside and provides a degree of safety for personnel against incidental contact.
The first criteria is typically whether the enclosure is for indoor or outdoor use. Outdoor enclosures can also be used indoors, though they are usually more expensive.
The most common manufactured enclosures comply with these ratings: NEMA 1 and 12 (indoor use only) and NEMA 3R, 4, 4X (indoor or outdoor use).
NEMA Rating Simplified Version
Indoor
- NEMA 1 – Protection from falling dirt.
- NEMA 2 – Protection from falling dirt and water.
- NEMA 5 – Protection from dirt, dust, fibers, lint, falling water, and light splashing.
- NEMA 12 – Protection from dirt, dust, fibers, lint, falling water, and light splashing.
- NEMA 13 – Protection from dirt, dust, fibers, lint, water seepage, oil, and non-corrosive liquids.
Outdoor
- NEMA 3 – Protection from dust, dirt, rain, snow, sleet; ice formation resistant.
- NEMA 3R – Protection from dirt, snow, sleet; ice formation resistant.
- NEMA 3S – Protection from dirt, snow, sleet; remains operable when ice-laden.
- NEMA 4 – Protection from dust, dirt, rain, snow, sleet, splashing water, hose water; ice resistant.
- NEMA 4X – Same as NEMA 4 plus corrosion protection.
- NEMA 6 – Protection from dust, dirt, rain, snow, sleet, hose water, temporary submersion; ice resistant.
- NEMA 6P – Same as NEMA 6 but allows prolonged submersion; corrosion protection.
Hazardous Locations
- NEMA 7 – Indoor use; Class I Div. 1 (Groups A, B, C, D); explosion containment.
- NEMA 8 – Indoor/outdoor use; Class I Div. 1 (Groups A, B, C, D); oil-immersed equipment prevents combustion.
- NEMA 9 – Indoor use; Class II Div. 1 (Groups E, F, G); prevents ignition of dust.
- NEMA 10 – Indoor/outdoor use; meets MSHA 30 CFR Part 18 requirements.
NEMA Standards Code (Non-Hazardous Locations)
In non-hazardous locations, enclosure Types provide protection against hazardous part access, solid objects, water ingress, and environmental conditions. Examples include:
- Type 1: Indoor; protects against access to hazardous parts and falling dirt.
- Type 2: Indoor; protects against dirt and dripping/splashing water.
- Type 3: Indoor/outdoor; protects against dirt, dust, rain, sleet, snow, ice.
- Type 3R: Indoor/outdoor; protects against dirt, rain, sleet, snow, ice.
- Type 3S: Indoor/outdoor; same as 3, remains operable when ice laden.
- Type 3X / 3RX / 3SX: Indoor/outdoor; adds corrosion resistance.
- Type 4: Indoor/outdoor; protects against dust, dirt, rain, splashing water, hose water, ice.
- Type 4X: Same as 4 with added corrosion resistance.
- Type 5: Indoor; protects against dust, lint, fibers, dripping and splashing water.
- Type 6: Indoor/outdoor; protects against hose water, temporary submersion, ice.
- Type 6P: Same as 6 with prolonged submersion and corrosion resistance.
- Type 12 / 12K: Indoor; protects against dirt, dust, fibers, dripping/splashing water (with or without knockouts).
NEMA Standards Code (Hazardous Locations)
In hazardous locations, enclosure ratings are designed for explosion protection, dust ignition prevention, or oil-immersion safety.
- Type 7: Indoor; Class I Div. 1 (Groups A–D); contains internal explosions.
- Type 8: Indoor/outdoor; Class I Div. 1 (Groups A–D); oil-immersed combustion prevention.
- Type 9: Indoor; Class II Div. 1 (Groups E–G); prevents combustible dust ignition.
- Type 10: Meets Mine Safety and Health Administration (MSHA) requirements, 30 CFR Part 18.
