NEMA 12 is for indoor dust and dripping liquid. NEMA 4 adds hose-down water and outdoor use. NEMA 4X is NEMA 4 plus a corrosion test, so it is the pick for washdown, salt and chemicals. The table shows what each rating is tested for, and the second table lists the Hammond and Stahlin series that carry each one.
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What each rating covers
| Protection (per NEMA 250) | Type 12 | Type 3R | Type 4 | Type 4X |
|---|---|---|---|---|
| Indoor use | Yes | Yes | Yes | Yes |
| Outdoor use | No | Yes | Yes | Yes |
| Circulating dust, lint, fibers | Yes | No | Yes (windblown dust) | Yes (windblown dust) |
| Dripping and light splashing liquid | Yes | Rain, sleet, snow | Yes | Yes |
| Hose-directed water | No | No | Yes | Yes |
| External ice does not damage it | No | Yes | Yes | Yes |
| Corrosion test | No | No | No | Yes |
| Knockouts allowed | No (12K has them) | Yes | No | No |
Source: NEMA 250, Enclosures for Electrical Equipment (1000 Volts Maximum), and UL 50E. The hose test sprays at least 65 gallons per minute through a 1 inch nozzle from 10 to 12 feet. Type 4X adds a corrosion test that Type 4 does not need to pass. Oil and coolant spray need Type 13; full submersion needs Type 6 or 6P.
Series that carry each rating
| Rating | Hammond series (examples) | Stahlin | Typical use |
|---|---|---|---|
| Type 12 | 1418 steel wallmount (1418A6), 1418Y freestanding (1418YD36, 72 x 36 x 36 in), 1414 junction boxes (1414A) | Stahlin parts on this site are 4X, see below | Control panels in clean, dry plant areas |
| Type 4 | 1418N4 steel wallmount (1418N4F8, 30 x 20 x 8 in), 1422N4 two door floormount (1422N4F12F), 1447SN4 disconnect (1447SN4B8) | See 4X | Outdoor panels and areas hosed down with plain water |
| Type 4X | 1418N4SS 304 stainless (1418N4SSB6), 1418N4S16 plus size code, 316 stainless (1418N4S16B6), 1418N4AL aluminum (1418N4ALB6), 1554 polycarbonate (1554B2GY) | Diamond Shield (DS60604W) and Classic (CL707W) fiberglass | Food and beverage washdown, wastewater, chemical and salt air |
Ratings shown are from the Hammond and Stahlin part data on each product page. Need a size that is not listed? Send the inside dimensions and rating and we get the part number from the factory.
Cooling has to match the rating
A fan or air conditioner mounted on the box must carry the same rating. Pfannenberg Filterfans come in NEMA 12 and NEMA 3R versions, so they fit Type 12 and 3R panels. For Type 4 and 4X, use a sealed air conditioner such as the DTS 3061 (NEMA 3R/4) or the DTS 3081 in 304 or 316 stainless (NEMA 4/4X). The enclosure cooling guide walks through the choice with numbers.
Common questions
Can a NEMA 4X box go in place of a NEMA 4 or 12?
Yes. A 4X enclosure passes every Type 4 test plus the corrosion test, and Type 4 covers what Type 12 covers for dust and dripping liquid. Going up a rating is always allowed. Going down is not.
Is stainless steel the only way to get 4X?
No. Fiberglass and polycarbonate boxes carry 4X too, like the Stahlin Diamond Shield and Classic series and the Hammond 1554 polycarbonate line. Aluminum Hammond 1418N4AL boxes are also listed 4X. Pick the material by the chemicals in the area.
304 or 316 stainless?
Both are 4X. 316 adds molybdenum, which holds up better against chlorides like salt and many cleaning chemicals. Hammond offers the 1418 wallmount in both: 1418N4SS parts (like 1418N4SSB6) are 304, and 1418N4S16 parts with a size code (like 1418N4S16B6) are 316.
Does the rating hold after I cut holes?
Only if every fitting, cooling unit and window you add carries the same rating. One NEMA 12 fan on a 4X box makes the panel a 12 at best.
Is NEMA 12 the same as IP54?
No. NEMA ratings can be converted to an IP code in one direction only, because IP codes do not test corrosion, ice, oil or gasket aging. If the spec calls out an IP code, send it and we match the enclosure that carries that code.
Get the enclosure quoted
Send the rating, size and material, or a competitor part number. We send back the Hammond or Stahlin match with lead time.
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Related: Hammond enclosures · Stahlin fiberglass enclosures · Enclosure cooling guide · Heat load calculator · All cross references
NEMA is a registered trademark of the National Electrical Manufacturers Association. UL is a registered trademark of UL LLC. This page summarizes the standards for selection only; check the current standard and the manufacturer datasheet before you specify.