Boxes, Enclosures, and Accessories Materials Selection & Requirements

This article is about Boxes, Enclosures, and Accessories Materials Selection & Requirements of Electrical Power System Systems as per International Codes and standards for Commercial Buildings, Plants and Refinery Projects.

Boxes, Enclosures, and Accessories Materials Selection & Requirements

Certifications

Boxes for use in Hazardous (Classified) locations shall be listed or labeled as meeting the requirements of UL 886.

General Material Requirements

Boxes and Enclosure Certification:
In outdoor plant areas, boxes and enclosures shall be certified by the manufacturer as:
(a) NEMA 250/NEMA ICS 6 Type 4; or
(b) NEMA Type 3 manufactured copper free cast aluminum (0.4 of 1% maximum), or plastic (including fiberglass); or
(c) IEC 60529 Type IP54 or better”
Box and Enclosure Certification:
In outdoor plant areas, outside the perimeter of process units, and other industrial areas, boxes and enclosures shall be certified by the manufacturer as:
(a) NEMA Type 3 or 4; or
(b) IEC 60529 Type IP54 or better”
Box and Enclosure Certification:
In outdoor plant and other industrial areas located in severe corrosive environments, boxes and enclosures shall be certified by the manufacturer as:
(a) NEMA Type 4X (except galvanized and/or painted or coated carbon steel sheet metal enclosures are not permitted); or
(b) NEMA Type 3 or 4, manufactured of copper free cast aluminum (0.4 of 1% copper maximum), or plastic (including fiberglass); or
(c) IEC 60529 Type IP 54 or better, manufactured of stainless steel (Type 304 or better), copper free cast aluminum, or plastic (including fiberglass).
Commentary Note:
In outdoor plant and other industrial areas located in severe corrosive environments, paragraph 7.3 supersedes paragraphs 7.1 and 7.2.”
Box and Enclosure Certification:
In outdoor non-industrial areas, boxes and enclosures shall be certified by the manufacturer as:
(a) NEMA Type 3R, 3 or 4; or
(b) IEC 60529 Type IP34 or better”
In outdoor locations, enclosures for small dry-type transformers shall be totally enclosed NEMA Type 3R. In severe corrosion environments, enclosure material shall be suitable for the application.
In hazardous (classified) locations, enclosures that are required to be approved for Class I locations by NEC Article 501 or 505, shall meet the hazardous area equipment application requirements of SAES-P-100 and the NEC.
“Enclosures that are rated:
(a) NEMA Type 3, 4 or 4X, or
(b) IEC 60529 Type IP54, or better, shall have Type 300 Series stainless steel hardware.
Exception: Aluminum enclosures may have aluminum or aluminum alloy hinges and operating handles.
Enclosures and junction boxes having an internal volume exceeding 2,000 cm³ shall be provided with Type 300 Series stainless steel breather and drain fittings, or a combination breather and drain fitting.
Unless otherwise specified, enclosures may meet water and dust tightness requirements (paragraphs 7.1 to 7.4) with openings for breathers and drains plugged.
Electrical materials shall be new and unused.
Electrical materials shall be in accordance with the Saudi Aramco-approved project-specific design drawings, diagrams, schedules, lists, databases, and associated documents (in particular, raceway type and trade size as shown on electrical BOM and raceway schedules).
Electrical materials shall be free of damage.
Electrical materials shall be identified by using tags, stamps, color coding, stencils or labels.
Electrical materials shall be traceable from the manufacturer and supplier through delivery, storage, fabrication, erection, installation, repair, modification and use.
Grounding Provisions:
A means shall be provided in each metal box for the connection of an equipment grounding conductor. The means shall be permitted to be a tapped hole or equivalent.
[NFPA 70, NEC 314.40 (D)]”
Covers:
Metal covers shall be of the same material as the box or conduit body with which they are used.
[NFPA 70, NEC 314.41]”
Bushings:
Where individual conductors pass through a metal cover, a separate hole equipped with a bushing of suitable insulating material shall be provided for each conductor.
[NFPA 70, NEC 314.42]”
Marking:
All boxes shall be durably and legibly marked with the manufacturer’s name or trademark. [NFPA 70, NEC 314.44]
Electrical materials shall conform to all applicable requirements, standards, and specifications prior to release to be used as part of the work.

Specific Material Requirements for Enclosures

The features of each enclosure type are applicable only when the enclosure is completely and properly installed. Enclosure type shall be as specified in attachment 1. [NEMA 250 Sec. 2]
IP Designations:
The degree of protection provided by an enclosure indicated by IP code shall be in accordance with attachments 2 and 3. [IEC 60529 Sec. 4]
Each enclosure shall be permanently marked with the manufacturer’s or private labeler’s name, trademark, or other descriptive marking by which the organization responsible for the product may be identified. [UL 886 Sec. 35.1(a)]
If a manufacturer produces boxes or fittings at more than one factory, each product shall have a distinctive marking, by which it may be identified as the product of a particular factory. [UL 886 Sec. 35.14]
A box may be marked with one or more enclosure type designations. [UL 886 Sec. 35.15]
A box may be marked “”Raintight””. [UL 886 Sec. 35.16]”
An enclosure shall not be thinner than specified in Table 3 or Table 4 (See Attachment 5). [UL 50 Sec. 6.4.1.1]
A sheet-metal door, front, cover, or auxiliary door shall not be thinner than as specified in Table 5 (See Attachment 6). [UL 50 Sec. 6.7.2.1]

Specific Material Requirements for Metallic Boxes

The features of each enclosure type are applicable only when the enclosure is completely and properly installed. Enclosure type shall be as specified in attachment 1. [NEMA 250 Sec. 2]
IP Designations:
The degree of protection provided by an enclosure indicated by IP code shall be in accordance with attachments 2 and 3. [IEC 60529 Sec. 4]
Each enclosure shall be permanently marked with the manufacturer’s or private labeler’s name, trademark, or other descriptive marking by which the organization responsible for the product may be identified. [UL 886 Sec. 35.1(a)]
If a manufacturer produces boxes or fittings at more than one factory, each product shall have a distinctive marking, by which it may be identified as the product of a particular factory. [UL 886 Sec. 35.14]
A box may be marked with one or more enclosure type designations. [UL 886 Sec. 35.15]
A box may be marked “”Raintight””. [UL 886 Sec. 35.16]
An enclosure shall not be thinner than specified in Table 3 or Table 4 (See Attachment 5). [UL 50 Sec. 6.4.1.1]
A sheet-metal door, front, cover, or auxiliary door shall not be thinner than as specified in Table 5 (See Attachment 6). [UL 50 Sec. 6.7.2.1]

Specific Material Requirements for Metallic Boxes

Standard BoA23:BA32arked with their volume shall be as given in Table 314.16(A) (Attachment 4). [NFPA 70, NEC 314.16(A)(1)]
Other Boxes:
Boxes 1650 cm³ (100 in.³) or less, other than those described in Table 314.16(A), and nonmetallic boxes shall be durably and legibly marked by the manufacturer with their volume. Boxes described in Table 314.16(A) (Attachment 4) that have a volume larger than is designated in the table shall be permitted to have their volume marked as required by this section. [NFPA 70, NEC 314.16(A)(2)]
Corrosion Resistant:
Metal boxes, conduit bodies, and fittings shall be corrosion resistant or shall be wellgalvanized, enameled, or otherwise properly coated inside
and out to prevent corrosion. [NFPA 70, NEC 314.40(A)]
Thickness of Metal:
Sheet steel boxes not over 1650 cm³ (100 in.³) in size shall be made from steel not less than 1.59 mm (0.0625 in.) thick. The wall of a malleable iron box or conduit body and a die-cast or permanent-mold cast aluminum, brass, bronze, or zinc box or conduit body shall not be less than 2.38 mm (3⁄32 in.) thick. Other cast metal boxes or conduit bodies shall have a wall thickness not less than 3.17 mm (1⁄8 in.). [NFPA 70, NEC 314.40(B)]
Metal Boxes Over 1650 cm³ (100 in.³):
Metal boxes over 1650 cm³ (100 in.³) in size shall be constructed so as
to be of ample strength and rigidity. If of sheet steel, the metal thickness shall not be less than 1.35 mm (0.053 in.) uncoated. [NFPA 70, NEC 314.40(C)]
Marking – Box Volume:
A cast metal box having a volume of 1640 cm³ (100 in³) or less, an extension ring, or a raised cover shall be permanently and legibly marked with a volume that does not exceed its actual volume. The marking shall be visible after installation. [UL 514A Sec. 5.5.1]

Specific Material Requirements for Nonmetallic Boxes

The inner and outer surfaces of a box or cover shall not be subject to peeling, scaling or flaking and shall be smooth and free from blisters, cracks, and other defects. In the case of a molded product, excess
flashing shall be removed from the mold line of all interior surfaces so that there are no sharp edges or undue obstructions to the passage of wiring or mating of parts in the intended use of the product. [UL 514C Sec. 5.1.2]
Thickness:
A blank cover, an outlet box cover, and the sides, end walls, and bottom of a box shall have athickness not less than that specified in Table 60.1 (Attachment 7). [UL 514C Sec. 60.2.1]

International Standard and Codes for Boxes, Enclosures, and Accessories

3. NFPA 70 – National Electrical Code (NEC).
4. SAES-P-104 – Wiring Methods and Materials.
5. SAES-P-100 – Basic Power System Design Criteria.
6. ANSI/IEC 60529 – American National Standard, Degrees of protection provided by enclosures (IP Code).
7. NEMA ICS 6 – Industrial Control and Systems: Enclosures.
8. NEMA 250 – Enclosures for Electrical Equipment (1000 Volts Maximum).
9. UL 50 – UL Standard for Enclosure for Electrical Equipments.
10. UL 514A – Metallic Outlet Boxes.
11. UL 514C – Nonmetallic Outlet Boxes, Flush-Device Boxes, and Covers.
12. UL 886 – Outlet Boxes and Fittings for Use in Hazardous (Classified) Locations.