Resolución 2535: adopta el Código Eléctrico Nacional, versión 1993. (Sustituye el Anejo A del Reglamento 4435)

D. Disconnecting and Guarding 240-40. Disconnecting Means for Fuses. Disconnecting means shall be provided on the supply side of all fuses in circuits of over 150 volts to ground and cartridge fuses in circuits of any voltage, where accessible to other than qualified persons, so that each individual circuit containing fuses can be independently disconnected from the source of electric energy. Exception No. 1: A device provided for current-limiting on the supply side of the service disconnecting means as permitted by Section 230-82. Exception No. 2: A single disconnecting means shall be permitted on the supply side of more than one set of fuses as provided by Section 430- 112 for group operation of motors and in Section 424-22 for fixed electric space heating equipment. 70-100 NATIONAL ELECTRICAL CODE 240-41. Arcing or Suddenly Moving Parts. Arcing or suddenly moving parts shall comply with (a) and (b) below. (a) Location. Fuses and circuit breakers shall be so located or shielded that persons will not be burned or otherwise injured by their operation. (b) Suddenly Moving Parts. Handles or levers of circuit breakers, and similar parts that may move suddenly in such a way that persons in the vicinity are likely to be injured by being struck by them, shall be guarded or isolated. E. Plug Fuses, Fuseholders, and Adapters 240-50. General. (a) Maximum Voltage. Plug fuses and fuseholders shall not be used in circuits exceeding 125 volts between conductors. Exception: In circuits supplied by a system having a grounded neutral and having no conductor at over 150 volts to ground. (b) Marking. Each fuse, fuseholder, and adapter shall be marked with its ampere rating. (c) Hexagonal Configuration. Plug fuses of 15-ampere and lower rating shall be identified by a hexagonal configuration of the window, cap, or other prominent part to distinguish them from fuses of higher ampere ratings. (d) No Energized Parts. Plug fuses, fuseholders, and adapters shall have no exposed energized parts after fuses or fuses and adapters have been installed. (e) Screw Shell. The screw shell of a plug-type fuseholder shall be connected to the load side of the circuit. 240-51. Edison-Base Fuses. (a) Classification. Plug fuses of the Edison-base type shall be classified at not over 125 volts and 30 amperes and below. (b) Replacement Only. Plug fuses of the Edison-base type shall be used only for replacements in existing installations where there is no evidence of overfusing or tampering. 240-52. Edison-Base Fuseholders. Fuseholders of the Edison-base type shall be installed only where they are made to accept Type S fuses by the use of adapters. 240-53. Type S Fuses. Type S fuses shall be of the plug type and shall comply with (a) and (b) below. (a) Classification. Type S fuses shall be classified at not over 125 volts and 0 to 15 amperes, 16 to 20 amperes, and 21 to 30 amperes. (b) Noninterchangeable. Type S fuses of an ampere classification as specified in (a) above shall not be interchangeable with a lower ampere classification. They shall be so designed that they cannot be used in any fuseholder other than a Type S fuseholder or a fuseholder with a Type S adapter inserted. ARTICLE 240 - OVERCURRENT PROTECTION 70-101 240-54. Type S Fuses, Adapters, and Fuseholders. (a) To Fit Edison-Base Fuseholders. Type S adapters shall fit Edisonbase fuseholders. (b) To Fit Type S Fuses Only. Type S fuseholders and adapters shall be so designed that either the fuseholder itself or the fuseholder with a Type S adapter inserted cannot be used for any fuse other than a Type S fuse. (c) Nonremovable. Type S adapters shall be so designed that once inserted in a fuseholder, they cannot be removed. (d) Nontamperable. Type S fuses, fuseholders, and adapters shall be so designed that tampering or shunting (bridging) would be difficult. (e) Interchangeability. Dimensions of Type S fuses, fuseholders, and adapters shall be standardized to permit interchangeability regardless of the manufacturer. F. Cartridge Fuses and Fuseholders 240-60. General. (a) Maximum Voltage-300-Volt Type. Cartridge fuses and fuseholders of the 300-volt type shall not be used in circuits of over 300 volts between conductors. Exception: In single-phase line-to-neutral circuits supplied from 3-phase, 4-wire, solidly grounded neutral systems where the line-to-neutral voltage does not exceed 300V. (b) Noninterchangeable-0-6000 Ampere Cartridge Fuseholders. Fuseholders shall be so designed that it will be difficult to put a fuse of any given class into a fuseholder that is designed for a current lower, or voltage higher, than that of the class to which the fuse belongs. Fuseholders for current-limiting fuses shall not permit insertion of fuses that are not current-limiting. (c) Marking. Fuses shall be plainly marked, either by printing on the fuse barrel or by a label attached to the barrel, showing the following: (1) ampere rating; (2) voltage rating; (3) interrupting rating where other than 10,000 amperes; (4) "current-limiting" where applicable; and (5) the name or trademark of the manufacturer. Exception: Interrupting rating marking shall not be required on fuses used for supplementary protection. 240-61. Classification. Cartridge fuses and fuseholders shall be classified according to voltage and amperage ranges. Fuses rated 600 volts, nominal, or less, shall be permitted to be used for voltages at or below their ratings. G. Circuit Breakers 240-80. Method of Operation. Circuit breakers shall be trip free and capable of being closed and opened by manual operation. Their normal method of operation by other than manual means, such as electrical or pneumatic, shall be permitted if means for manual operation is also provided. 70-102 NATIONAL ELECTRICAL CODE Exception: As provided in Section 230-76(2) for circuit breakers used as service disconnecting means. 240-81. Indicating. Circuit breakers shall clearly indicate whether they are in the open "off" or closed "on" position. Where circuit breaker handles are operated vertically rather than rotationally or horizontally, the "up" position of the handle shall be the "on" position. 240-82. Nontamperable. A circuit breaker shall be of such design that any alteration of its trip point (calibration) or the time required for its operation will require dismantling of the device or breaking of a seal for other than intended adjustments. 240-83. Marking. (a) Durable and Visible. Circuit breakers shall be marked with their ampere rating in a manner that will be durable and visible after installation. Such marking shall be permitted to be made visible by removal of a trim or cover. (b) Location. Circuit breakers rated at 100 amperes or less and 600 volts or less shall have the ampere rating molded, stamped, etched, or similarly marked into their handles or escutcheon areas. (c) Interrupting Rating. Every circuit breaker having an interrupting rating other than 5000 amperes shall have its interrupting rating shown on the circuit breaker. Exception: Interrupting rating marking shall not be required on circuit breakers used for supplementary protection. If a circuit breaker is used on a circuit having an available fault current higher than its marked interrupting rating by being connected on the load side of an acceptable overcurrent-protective device having the higher rating, this additional series combination interrupting rating shall be marked on the end use equipment, such as switchboards and panelboards. (d) Circuit Breakers Used as Switches. Where used as switches in 120- volt and 277-volt fluorescent lighting circuits, circuit breakers shall be listed and shall be marked "SWD." (e) Voltage Marking. Circuit breakers shall be marked with a voltage rating no less than the nominal system voltage that is indicative of their capability to interrupt fault currents between phases or phase to ground. (FPN): A circuit breaker with a straight voltage rating, e.g., 240V or 480V, may be applied in a circuit in which the nominal voltage between any two conductors does not exceed the circuit breaker's voltage rating; except that a two-pole circuit breaker is not suitable for protecting a 3-phase corner-grounded delta circuit unless it is marked 1-phase/3-phase to indicate such suitability. A circuit breaker with a slash rating, e.g., 120/240V or 480Y/277V, may only be applied in a circuit in which the nominal voltage to ground from any conductor does not exceed the lower of the two values of the circuit breaker's voltage rating and the nominal voltage between any two conductors does not exceed the higher value of the circuit breaker's voltage rating.