Equipment intended to interrupt current at fault levels shall have a minimum interrupting rating of 10,000 amperes. Equipment intended to interrupt current at levels other than fault levels shall have an interrupting rating at nominal circuit voltage of not less than the current that must be interrupted. (110.9)
The overcurrent protective devices, total impedance, equipment short-circuit current ratings and other characteristics of the circuit to be protected shall be so selected and coordinated as to permit the circuit protective devices that are used to clear a fault to do so without extensive damage to the electrical equipment of the circuit. This fault shall be assumed to be either between two or more of the circuit conductors or between any circuit conductor and the equipment grounding conductors permitted in Section E3908.8. Listed equipment applied in accordance with its listing shall be considered to meet the requirements of this section. (110.10)
Enclosures, other than surrounding fences or walls, of panelboards, meter sockets, enclosed switches, transfer switches, circuit breakers, pullout switches and motor controllers, rated not over 600 volts nominal and intended for such locations, shall be marked with an enclosure-type number as shown in Table E3404.4.
Table E3404.4 shall be used for selecting these enclosures for use in specific locations other than hazardous (classified) locations. The enclosures are not intended to protect against conditions such as condensation, icing, corrosion, or contamination that might occur within the enclosure or enter through the conduit or unsealed openings. (110.28)
TABLE E3404.4 (Table 110.28) ENCLOSURE SELECTION
Table E3404.4 shall be used for selecting these enclosures for use in specific locations other than hazardous (classified) locations. The enclosures are not intended to protect against conditions such as condensation, icing, corrosion, or contamination that might occur within the enclosure or enter through the conduit or unsealed openings. (110.28)
TABLE E3404.4 (Table 110.28) ENCLOSURE SELECTION
| PROVIDES A DEGREE OF PROTECTION AGAINST THE FOLLOWING ENVIRONMENTAL CONDITIONS | FOR OUTDOOR USE | |||||||||
| Enclosure-type Number | ||||||||||
| 3 | 3R | 3S | 3X | 3RX | 3SX | 4 | 4X | 6 | 6P | |
| Incidental contact with the enclosed equipment | X | X | X | X | X | X | X | X | X | X |
| Rain, snow and sleet | X | X | X | X | X | X | X | X | X | X |
| Sleeta | ‒ | ‒ | X | ‒ | ‒ | X | ‒ | ‒ | ‒ | ‒ |
| Windblown dust | X | ‒ | X | X | ‒ | X | X | X | X | X |
| Hosedown | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | X | X | X | X |
| Corrosive agents | ‒ | ‒ | ‒ | X | X | X | ‒ | X | ‒ | X |
| Temporary submersion | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | X | X |
| Prolonged submersion | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | X |
| PROVIDES A DEGREE OF PROTECTION AGAINST THE FOLLOWING ENVIRONMENTAL CONDITIONS | FOR INDOOR USE | |||||||||
| Enclosure-type Number | ||||||||||
| 1 | 2 | 4 | 4X | 5 | 6 | 6P | 12 | 12K | 13 | |
| Incidental contact with the enclosed equipment | X | X | X | X | X | X | X | X | X | X |
| Falling dirt | X | X | X | X | X | X | X | X | X | X |
| Falling liquids and light splashing | ‒ | X | X | X | X | X | X | X | X | X |
| Circulating dust, lint, fibers and flyings | ‒ | ‒ | X | X | ‒ | X | X | X | X | X |
| Settling airborne dust, lint, fibers and flings | ‒ | ‒ | X | X | X | X | X | X | X | X |
| Hosedown and splashing water | ‒ | ‒ | X | X | ‒ | X | X | ‒ | ‒ | ‒ |
| Oil and coolant seepage | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | X | X | X |
| Oil or coolant spraying and splashing | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | X |
| Corrosive agents | ‒ | ‒ | ‒ | X | ‒ | ‒ | X | ‒ | ‒ | ‒ |
| Temporary submersion | ‒ | ‒ | ‒ | ‒ | ‒ | X | X | ‒ | ‒ | ‒ |
| Prolonged submersion | ‒ | ‒ | ‒ | ‒ | ‒ | ‒ | X | ‒ | ‒ | ‒ |
| a. Mechanism shall be operable when ice covered. |
| Note 1: The term raintight is typically used in conjunction with Enclosure Types 3, 3S, 3SX, 3X, 4, 4X, 6 and 6P. The term rainproof is typically used in conjunction with Enclosure Types 3R and 3RX. The term watertight is typically used in conjunction with Enclosure Types 4, 4X, 6 and 6P. The term driptight is typically used in conjunction with Enclosure Types 2, 5, 12, 12K and 13. The term dusttight is typically used in conjunction with Enclosure Types 3, 3S, 3SX, 3X, 5, 12, 12K and 13. |
| Note 2: Ingress protection (IP) ratings are found in ANSI/NEMA 60529, Degrees of Protection Provided by Enclosures. IP ratings are not a substitute for enclosure-type ratings. |
Unused openings, other than those intended for the operation of equipment, those intended for mounting purposes, and those permitted as part of the design for listed equipment, shall be closed to afford protection substantially equivalent to the wall of the equipment. Where metallic plugs or plates are used with nonmetallic enclosures they shall be recessed at least 1/4 inch (6.4 mm) from the outer surface of the enclosure. [110.12(A)]
Internal parts of electrical equipment, including busbars, wiring terminals, insulators and other surfaces, shall not be damaged or contaminated by foreign materials such as paint, plaster, cleaners or abrasives, and corrosive residues. There shall not be any damaged parts that might adversely affect safe operation or mechanical strength of the equipment such as parts that are broken; bent; cut; deteriorated by corrosion, chemical action, or overheating. Foreign debris shall be removed from equipment. [110.12(B)]
Approved enclosures shall guard energized parts that are operating at 50 volts or more against accidental contact. [110.27(A)]
In locations where electrical equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage. [110.27(B)]
The manufacturer's name, trademark or other descriptive marking by which the organization responsible for the product can be identified shall be placed on all electric equipment. Other markings shall be provided that indicate voltage, current, wattage or other ratings as specified elsewhere in Chapters 34 through 43. The marking shall have the durability to withstand the environment involved. [110.21(A)]
Where caution, warning, or danger signs or labels are required by this code, the labels shall meet the following requirements:
1. The marking shall adequately warn of the hazard using effective words, colors, or symbols or combinations of such.
2. Labels shall be permanently affixed to the equipment or wiring method.
3. Labels shall not be hand written except for portions of labels or markings that are variable, or that could be subject to changes. Labels shall be legible.
4. Labels shall be of sufficient durability to withstand the environment involved. [110.21(B)]
1. The marking shall adequately warn of the hazard using effective words, colors, or symbols or combinations of such.
2. Labels shall be permanently affixed to the equipment or wiring method.
3. Labels shall not be hand written except for portions of labels or markings that are variable, or that could be subject to changes. Labels shall be legible.
4. Labels shall be of sufficient durability to withstand the environment involved. [110.21(B)]
Each disconnecting means shall be legibly marked to indicate its purpose, except where located and arranged so that the purpose is evident. The marking shall have the durability to withstand the environment involved. [110.22(A)]