ANSI NEMA 250-2020 PDF

Full title and description

ANSI/NEMA 250-2020 — Enclosures for Electrical Equipment (1,000 Volts Maximum). Standard that defines NEMA enclosure Types, construction, performance tests, markings and application guidance for enclosures used with electrical equipment rated not more than 1,000 V (including indoor, outdoor and hazardous-location types).

Abstract

ANSI/NEMA 250-2020 specifies the requirements for enclosures intended to protect electrical equipment (≤1000 V) from access to hazardous parts and from specific environmental conditions (dust, water, dripping, splashing, hose-directed water, submersion, corrosion, icing in some Types, etc.). It defines NEMA enclosure Type designations, required construction features, test procedures, marking and information for field modification and installation. The standard is aligned for use with manufacturer instructions and Section 110.3(B) of NFPA 70 (NEC).

General information

• Status: Superseded / rescinded as the active 250 series has been updated; the 2020 edition is a historical edition (see ANSI/NEMA EN 10250:2024 as the replacement).
• Publication date: 2020 (ANSI/NEMA 250-2020 edition).
• Publisher: National Electrical Manufacturers Association (NEMA); also published/available through ANSI webstore.
• ICS / categories: 29 — Electrical engineering (examples: 29.020 Electrical engineering in general; 29.100 Components for electrical equipment; 29.130 Switchgear and controlgear).
• Edition / version: 2020 edition (ANSI/NEMA 250-2020).
• Number of pages: Approximately 61 pages (publisher format may vary).

Scope

Applies to enclosures for electrical equipment rated not more than 1,000 volts intended for: (a) indoor locations (Types 1, 2, 5, 12, 12K, 13); (b) indoor or outdoor locations (Types 3, 3X, 3R, 3RX, 3S, 3SX, 4, 4X, 6, 6P); and (c) hazardous (classified) locations (Types 7 and 9). The scope covers construction, required features, performance and design tests, markings, allowable field modifications and intended applications; it does not address every possible environmental hazard (for example, specific condensation control, gas vapor ignition characteristics, or certain contamination scenarios may be outside its direct coverage).

Key topics and requirements

• Definition and description of NEMA enclosure Types and the environmental/operational protections each Type provides.
• Construction and material requirements for enclosures (frames, gaskets, doors, latches, finish and corrosion resistance considerations).
• Required design and performance tests (e.g., ingress of solid foreign objects, water-spray/hose tests, rain/ice and submersion tests for specified Types, impact and load tests as applicable).
• Marking, nameplate and documentation requirements, including Type designation and any ancillary ratings (for example PW for high-pressure power-wash cleaning).
• Guidance on field modification, repair, and installation practices to maintain the intended degree of protection.
• Limits and exclusions — conditions not fully covered by the standard and the need to follow manufacturer instructions and NEC (ANSI/NFPA 70) where applicable.
• Relationship and comparison considerations with IEC 60529 (IP codes) — mapping guidance and notes on non-equivalence of the two systems.

Typical use and users

Used by enclosure and electrical equipment manufacturers, product designers and engineers, electrical inspectors and authorities having jurisdiction (AHJs), testing laboratories, OEMs, specification writers, distributors and facility/maintenance personnel who select and install enclosures for industrial, commercial and certain hazardous-area applications. It is a primary reference when specifying NEMA enclosure Types and when documenting required environmental protection for low-voltage electrical equipment (≤1,000 V).

Related standards

Commonly referenced standards and guidance include: IEC 60529 / EN 60529 (IP Code — ingress protection), ANSI/IEC 60529 (U.S. adoption of IP code), UL/CSA enclosure standards (e.g., UL 50 / UL 50E and related UL documents), NFPA 70 (NEC) — section 110.3(B) for installation and manufacturer instructions, NEMA technical bulletins and comparison guides (NEMA guidance comparing NEMA 250 and IEC 60529), and the newer consolidated edition ANSI/NEMA EN 10250:2024 which supersedes the 2020 edition.

Keywords

NEMA 250, ANSI/NEMA 250-2020, electrical enclosures, NEMA enclosure Types, ingress protection, IP code, enclosure tests, 1,000 volts maximum, enclosure marking, PW rating, enclosure construction, NEC 110.3(B).

FAQ

Q: What is this standard?

A: ANSI/NEMA 250-2020 is the NEMA standard that defines enclosure Types and the construction, testing and marking requirements for enclosures used with electrical equipment rated up to 1,000 volts.

Q: What does it cover?

A: It covers the classification of enclosure Types (indoor, outdoor, hazardous), required construction and materials, performance and design tests to verify protection against solids and liquids, marking and documentation, and guidance for field modification and installation. It does not replace installation rules in the NEC and does not address every environmental hazard (users should follow manufacturer instructions and applicable codes).

Q: Who typically uses it?

A: Manufacturers, product designers, electrical engineers, testing laboratories, specification writers, AHJs and maintenance staff who need to select, test, specify or approve enclosures for electrical equipment up to 1,000 V.

Q: Is it current or superseded?

A: The 2020 edition is a historical edition. NEMA has moved the 250 series forward and published a revised consolidation under ANSI/NEMA EN 10250:2024 (published August 9, 2024). Many organizations now reference the 2024 consolidated edition; verify which edition is required by your project or authority having jurisdiction and use the currently mandated edition.

Q: Is it part of a series?

A: Yes. NEMA 250 is part of the NEMA standards addressing equipment and enclosure performance. It is commonly used alongside related NEMA publications and cross-referenced standards (IEC/EN 60529 for IP codes, UL enclosure standards, and NEC requirements). Newer NEMA/ANSI consolidated editions (for example ANSI/NEMA EN 10250:2024) integrate updates and harmonization with IEC guidance.

Q: What are the key keywords?

A: NEMA 250, enclosure Types, NEMA rating, ingress protection, IP code, enclosures for electrical equipment, 1000 V maximum, enclosure testing, construction, marking, ANSI/NEMA EN 10250-2024.