Pay Attention to Enclosure Codes

The International Protection Rating code numbers specified in IEC 60529 will let you know about products you buy and will let you offer an “IP rating” for the products you design and manufacture. The two-digit code indicates the level of protection against the entry, or ingress, of solid objects and about protection of equipment against the entry of liquids. Manufacturers use a nomenclature such as IP65 to tell buyers their equipment comes in a dust-tight enclosure (5) that can withstand high-pressure water sprayed from a nozzle (6). The higher the numbers, the better, but usually at higher cost. (Codes range from IP00 as high as IP68.)

The numbers have specific meanings defined in the IEC 60529 document, but if you don’t have that document close at hand, you can find charts of the solid-object- and liquid-protection values in many places. The Wikipedia contains a helpful list of the codes en.wikipedia.org/wiki/IP_Code.

This Wikipedia entry also lists values for a third digit that manufacturers have used to indicate the level of protection against impact damage. Now, though, a newer standard, IEC 62262 (2002), uses an IK scale to rate resistance to impact damage for equipment that has a rated voltage not greater than 72.5 KV. See: < href=”http://en.wikipedia.org/wiki/EN_50102″>en.wikipedia.org/wiki/EN_50102.

The IEC 62262 document has the formal name, “Degrees of Protection Provided by Enclosures for Electrical Equipment Against External Mechanical Impacts (IK Code).” And you can find IEC 60529 as, “Degrees of Protection Provided by Enclosures (IP Code).” I find the IHS Web site useful for getting a short abstract of these types of standards. IHS also sells hardcopy of electronic versions of national and international standards: electronics.ihs.com.

NEMA has ratings, too.

NEMA also has enclosure standards for nonhazardous locations that range from Type 1 to Type 13, with several subranges. According to NEMA, a Type 5 enclosure is, “…constructed for indoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and settling airborne dust, lint, fibers, and flyings); and to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (dripping and light splashing).” (I have no idea what a flying is. Perhaps filings?)

This outdoor OSVP-14127 enclosure from DDB Unlimited has a NEMA Type 4 or Type 4X rating. www.ddbunlimited.com.

Engineers should consult the document, “Enclosures for Electrical Equipment (1000 Volts Maximum),” NEMA Standards Publication 250-2003, for complete details. NEMA does provide abbreviated information via its Web site at: www.nema.org/prod/be/enclosures/upload/NEMA_Enclosure_Types_11-05-2.doc. –Jon Titus