NEMA Enclosure Types

NEMA Enclosure Types
Referencing the first character, 4, in the IP rating and the row designated “IP4_” in the leftmost column in the table; the blocks in Column “A” for NEMA Types 3,
3X, 3S, 3SX, 4, 4X, 5, 6, 6P, 12, 12K, and 13 are shaded. These NEMA ratings meet and exceed the IEC protection requirements against access to hazardous
parts and solid foreign objects.
Referencing the second character, 5, in the IP rating and the row designated “IP_5” in the rightmost column in the table; the blocks in Column “B” for NEMA
Types 3, 3X, 3S, 3SX, 4, 4X, 6, and 6P are shaded. These NEMA ratings meet and exceed the IEC requirements for protection against the ingress of water. The
absence of shading in Column “B” beneath the “NEMA Enclosure Type 5” indicates that Type 5 does not meet the IP 45 protection requirements against the
ingress of water. Likewise the absence of shading in Column “B” for NEMA Type 12, 12K and 13 enclosures indicates that these enclosures do not meet the IP
45 requirements for protection against the ingress of water. Only Types 3, 3X, 3S, 3SX, 4, 4X, 6, and 6P have both Column “A” in the “IP4_” row and Column “B”
in the “IP_5” row shaded and could be used in an IP45 application.
The NEMA Enclosure Type 3 not only meets the IP 45 Enclosure Rating, but also exceeds the IEC requirements because the NEMA Type
requires an outdoor corrosion test; a gasket aging test; a dust test; an external icing test; and no water penetration in the rain test. Slight
differences exist between the IEC and NEMA test methods, but the IEC rating
permits the penetration of water if “it does not deposit on
insulation parts, or reach live parts.” The IEC rating does
not require a corrosion test; gasket aging test; dust test or external icing test. Because
the NEMA ratings include additional test requirements, this table
cannot be used to select IP Designations for NEMA rated enclosure
specifications.
IEC 60529 specifies that an enclosure shall only be designated with a stated degree of protection indicated by the first characteristic numeral if it also complies
with all lower degrees of protection. Furthermore IEC 60529 states that an enclosure shall only be designated with a degree of protection indicated by the second
characteristic numeral if it also complies with all lower degrees of protection up to and including the second characteristic numeral 6. An enclosure designated
with a second characteristic numeral 7 or 8 only is considered unsuitable for exposure to water jets (designated by second characteristic numeral 5 or 6) and
need not comply with requirements for numeral 5 or 6 unless it is dual coded. Since the IEC protection requirements become more stringent with increasing IP
character value up through 6, once a NEMA Type rating meets the requirements for an IP designation up through 6, it will also meet the requirements for all
lower IP designations. This is apparent from the shaded areas shown in the table.
National Electrical Manufacturers Association Approved by NEMA Enclosures Section
1300 N. 17
th
Street, Suite 1752 November 2005
Rosslyn, VA 22209