This document "A Brief Comparison of NEMA 250—Enclosures for Electrical Equipment (1000 Volts Maximum) and IEC 60529—Degrees of Protection Provided by Enclosures (IP Code) is a NEMA Standards Publication.
In most instances, IEC 60529 IP ratings is used in equipment ingress protection ratings. However, when a design is to developed using North American standards, NEMA standards will be used. One of this is NEMA 250 which covers electrical enclosures up to 1000 Volts.
It is important to note that ANSI has adopted IEC 60529 as ANSI/IEC 60529. This American National Standard is an adoption of IEC 60529, Edition 2.0, Degrees of protection provided by enclosures (IP Code) and was developed and approved in accordance with procedures set forth by the American National Standards Institute. This Standard contains all the original text from IEC 60529, Edition 2.0.
NEMA 250
The National Electrical Manufacturers Association (NEMA) creates standards for electrical equipment, including enclosures. The enclosure “type” refers to the types of conditions under which they provide optimal performance. When NEMA 250 applies a rating of 1,2, etc., it signifies what type of enclosure it is.
This Standard covers enclosures for electrical equipment rated not more than 1000 Volts and intended to be installed and used as follows:
- enclosures for indoor locations
- enclosures for indoor or outdoor locations
- enclosures for hazardous (classified) locations
This Standard covers the requirements to provide protection to the enclosed equipment against specific environmental conditions. The requirements of this Standard mandate that enclosures and equipment shall be installed and used in accordance with manufacturer’s instructions.
IEC 60529 Scope
IEC 60529 is a standard developed through the International Electrotechnical Commission (IEC) that describes a system for classifying the degrees of protection provided by an enclosure. An “enclosure” as used in IEC 60529 is defined as “a part providing protection of equipment against certain external influences and in any direction protection against direct contact.” As such, IEC 60529 may be applied to products other than just metal or polymeric enclosures for electrical equipment for particular environmental conditions as covered by NEMA 250. As an example, a circuit breaker, switch, contactor, etc. may have an IEC 60529 IP rating, until it is enclosed in a metal or polymeric enclosure, NEMA 250 would not apply.
IEC 60529 is NOT a “product standard” and does not cover enclosure requirements other than the “degree of protection” provided. For instance IEC 60529 does not specify the corrosion protection and other environmental operating requirements and tests defined in NEMA 250.
IP Codes can not be converted NEMA 250 ratings
- Construction requirements
- Door and cover securement
- Corrosion resistance
- Effects of icing
- Gasket aging and oil resistance
- Coolant effects
The Type designation in NEMA 250 specifies requirements for these additional performance protections. For this reason, the IEC enclosure IP Code designations cannot be converted to enclosure Type numbers. NEMA enclosure type numbers however could be directly converted into equivalent IP rating as shown in below table.
For a more detailed NEMA 250 and IEC 60529 comparison, download the document here.