NEMA Enclosure Ratings Chart

Which enclosure survives which environment: the outdoor and indoor selection matrices behind NEC Table 110.28 (from NEMA 250), a per-type summary with approximate IP equivalents, and the IEC 60529 digit decoder. Find your worst environmental condition, read across to the types that check the box, and remember the conversion only runs one way — NEMA proves IP, never the reverse.

Outdoor locations

NEC 110.28

Enclosure types providing a degree of protection against outdoor environmental conditions (per NEC Table 110.28 / NEMA 250). A check means the type is rated for the condition; the X suffix adds corrosion protection to its base type.
Protection against	3	3X	3R	3RX	3S	3SX	4	4X	6	6P
Access to hazardous parts	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Rain, snow, and sleet	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Sleet — external mechanisms operable when ice-covered					✓	✓
Windblown dust, lint, fibers, and flyings	✓	✓			✓	✓	✓	✓	✓	✓
Hosedown							✓	✓	✓	✓
Corrosive agents		✓		✓		✓		✓		✓
Occasional temporary submersion									✓	✓
Occasional prolonged submersion										✓

Indoor locations

NEC 110.28

Enclosure types providing a degree of protection against indoor environmental conditions (per NEC Table 110.28 / NEMA 250). Types 4, 4X, 6, and 6P appear in both tables — they are rated indoor or outdoor.
Protection against	1	2	4	4X	5	6	6P	12	12K	13
Access to hazardous parts	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Falling dirt	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Dripping and light splashing liquids		✓	✓	✓	✓	✓	✓	✓	✓	✓
Circulating dust, lint, fibers, and flyings			✓	✓		✓	✓	✓	✓	✓
Settling airborne dust, lint, fibers, and flyings			✓	✓	✓	✓	✓	✓	✓	✓
Hosedown and splashing water			✓	✓		✓	✓
Oil and coolant seepage								✓	✓	✓
Oil or coolant spraying and splashing										✓
Corrosive agents				✓			✓
Occasional temporary submersion						✓	✓
Occasional prolonged submersion							✓

Type summary & approximate IP equivalents

NEMA 250 / IEC 60529

Where each type is used and the approximate IP rating it meets or exceeds. Published equivalence charts disagree for several types (the NEMA appendix prints conservative minimums; manufacturers publish tested values) — those cells show the span of published equivalents. Conversion is one-directional: an IP rating never demonstrates a NEMA type.
NEMA type	Use	Meets / exceeds (approx.)	In one line
1	Indoor	IP10–20	General purpose — contact and falling dirt only
2	Indoor	IP11–22	Adds dripping and light splashing
3	Indoor / outdoor	IP54–64	Rain, sleet, windblown dust
3R	Indoor / outdoor	IP14–24	Rain and sleet — no dust protection
3S	Indoor / outdoor	IP54–64	Type 3 + mechanisms operable under ice
3X	Indoor / outdoor	IP54–64	Type 3 + corrosion resistance (X applies to 3RX / 3SX too)
4	Indoor / outdoor	IP66	Hosedown-tight
4X	Indoor / outdoor	IP66	Hosedown-tight + corrosion (washdown, marine)
5	Indoor	IP52–54	Settling dust, drips
6	Indoor / outdoor	IP67	Temporary submersion
6P	Indoor / outdoor	IP67	Prolonged submersion + corrosion
12	Indoor	IP52–55	Industrial — circulating dust, drips, seepage (no knockouts)
12K	Indoor	IP52–55	Type 12 with knockouts
13	Indoor	IP54–65	Adds oil / coolant spray (machine tools)

Ranged cells (e.g. IP52–55 for Type 12) span the published charts; the low end is the NEMA-appendix minimum, the high end typical manufacturer-tested ratings. For a guaranteed IP number, read the specific product's label — dual-rated enclosures are the norm.

IP digit decoder

IEC 60529

What each IP digit means: first digit = solids and personnel contact, second digit = water (per IEC 60529). Higher digits include all lower protections through 6; a second digit of 7 or 8 covers immersion only and does not imply jet resistance unless dual-coded (e.g. IP66/IP68).
Digit	First digit — solids & contact	Second digit — water
0	No protection	No protection
1	Objects over 50 mm (back of hand)	Vertically dripping water
2	Objects over 12.5 mm (fingers)	Dripping water, enclosure tilted 15°
3	Objects over 2.5 mm (tools, wires)	Spraying water to 60° from vertical
4	Objects over 1 mm (fine tools, wires)	Splashing water from any direction
5	Dust-protected (limited ingress)	Low-pressure water jets, any direction
6	Dust-tight (no ingress)	Powerful water jets
7	—	Temporary immersion (0.15–1 m)
8	—	Continuous immersion per manufacturer

How to pick a type

Work from the nastiest condition the enclosure will ever see, not the average day. Rain alone is Type 3R territory; add windblown dust and it's a 3; add a pressure washer and nothing below a 4 survives; add chemicals or salt and the X suffix stops being optional. Indoors, the industrial default is Type 12 (dust and drips, no knockouts), and machine tools that mist coolant push you to 13. NEC 110.28 makes this enforceable: enclosures must be marked with a type number, and the marked type has to match the environment. One honest simplification here: hazardous-location enclosures (Types 7, 8, 9, 10, for classified areas) are a different subject with their own rules and are not in these tables.

Why NEMA→IP only runs one way

An IP code tests exactly two things: solid ingress and water ingress. A NEMA type tests those plus corrosion, gasket aging, external icing, and oil exposure, depending on the type — so a Type 4X demonstrably meets IP66, but an IP66 box has proven nothing about rust, ice, or coolant. Spec sheets that "convert" IP to NEMA are the classic submittal red flag. When both systems matter (imported gear, international specs), buy dual-rated enclosures and check both marks on the label.

Common questions

What is the difference between NEMA 4 and NEMA 4X?

One thing: corrosion. Both are hosedown-tight, dust-tight, and rated indoor or outdoor (≈IP66), but 4X adds the corrosion-protection test — which is why washdown food plants, wastewater sites, and marine work spec 4X (stainless or fiberglass) while a painted-steel 4 covers ordinary industrial hose-down. The same X logic applies outdoors: 3X, 3RX, and 3SX are their base types plus corrosion resistance.

Is NEMA 4X the same as IP66?

It meets or exceeds IP66 — but the reverse is not true, and that direction matters. The NEMA test regime includes corrosion, gasket aging, external icing, and oil tests that IEC 60529 never runs, so an IP66 enclosure cannot be assumed to satisfy a 4X spec. Convert NEMA→IP freely; never IP→NEMA.

Which NEMA type do I need for an outdoor panel?

Start at 3R for ordinary rain-tight service equipment (it tolerates rain and sleet but not windblown dust or hosedown), 3 where windblown dust is real, 4 where it will be hosed or heavily splashed, and add the X for corrosive sites. If it can flood, 6 (temporary) or 6P (prolonged submersion). NEC 110.28 requires the enclosure to be marked with its type and selected per this table.

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