INDUSTRIAL MACHINERY

670-1. Scope. This article covers the definition of, the size and overcurrent protection of supply conductors to, and the nameplate data required on industrial metalworking machine tools, woodworking machinery, plastics machinery, and mass production equipment, not portable by hand. (FPN): For further information, see Electrical Standard for Industrial Machinery, NFPA 79-1991 (ANSI). 670-2. Definition of Industrial Machinery. For the purposes of this article, a machine tool is defined as a power-driven machine not portable by hand, used to shape or form metal or plastic by cutting, impact, pressure, electrical techniques, or a combination of these processes. Plastics machinery is defined as a power-driven machine not portable by hand, used to shape or form plastic by application of thermal and/or mechanical energy, by cutting, impact, pressure, or a combination of these processes. Mass production industrial equipment is defined as a systematic array of one or more machine tools, plastics machinery, or assembly machines that is not portable by hand and that includes any associated material handling, manipulating, gaging, measuring, or inspection equipment. 670-3. Machine Nameplate Data. (a) Permanent Nameplate. A permanent nameplate that lists supply voltage, phase, frequency, full-load current, the maximum ampere rating of the short-circuit and ground-fault protective device, ampere rating of largest motor or load, short-circuit interrupting capacity of the machine overcurrent-protective device, if furnished, and diagram number shall be attached to the control equipment enclosure or machine where plainly visible after installation. The full-load current shown on the nameplate shall not be less than the sum of the full-load currents required for all motors and other equipment that may be in operation at the same time under normal conditions of use. Where unusual type loads, duty cycles, etc., require oversized conductors, the required capacity shall be included in the marked "full-load current." Where more than one incoming supply circuit is to be provided, the nameplate shall state the above information for each circuit. (b) Overcurrent Protection. Where overcurrent protection is provided in accordance with Section 670-4(b), the machine shall be marked "overcurrent protection provided at machine supply terminals." 670-4. Supply Conductors and Overcurrent Protection. (a) Size. The size of the supply conductor shall be such as to have an ampacity not less than 125 percent of the full-load current rating of all resistance heating loads plus 125 percent of the full-load current rating of highest rated motor plus the sum of the full-load current ratings of all other connected motors and apparatus that may be in operation at the same time. (FPN): See the 0-2000 volt ampacity tables of Article 310 for ampacity of conductors rated 600 volts and below. 70-690 NATIONAL ELECTRICAL CODE (b) Overcurrent Protection. A machine shall be considered as an individual unit and therefore shall be provided with a disconnecting means. The disconnecting means shall be permitted to be supplied by branch circuits protected by either fuses or circuit breakers. The disconnecting means shall not be required to incorporate overcurrent protection. Where furnished as part of the machine, overcurrent protection shall consist of a single circuit breaker or set of fuses, the machine shall bear the marking required in Section 670-3, and the supply conductors shall be considered either as feeders or taps as covered by Section 240-21. The rating or setting of the overcurrent-protective device for the circuit supplying the machine shall not be greater than the sum of the largest rating or setting of the branch-circuit short-circuit and ground-fault protective device provided with the machine, plus 125 percent of the full-load current rating of all resistance heating loads, plus the sum of the full-load currents of all other motors and apparatus that may be in operation at the same time. Exception: Where one or more instantaneous trip circuit breakers or motor short-circuit protectors are used for motor branch-circuit shortcircuit and ground-fault protection as permitted by Section 430-52(a), the procedure specified above for determining the maximum rating of the protective device for the circuit supplying the machine shall apply with the following provision. For the purpose of the calculation, each instantaneous trip circuit breaker or motor short-circuit protector shall be assumed to have a rating not exceeding the maximum percentage of motor full-load current permitted by Table 430-152 for the type of machine supply circuit protective device employed. Where no branch-circuit short-circuit and ground-fault protective device is provided with the machine, the rating or setting of the overcurrent-protective device shall be based on Sections 430-52 and 430-53 as applicable. 670-5. Clearance. Where the conditions of maintenance and supervision assure that only qualified persons will service the installation, the dimensions of the working space in the direction of access to live parts operating at not over 150 volts that are likely to require examination, adjustment, servicing, or maintenance while energized shall be a minimum of 2½ feet (762 mm). Where controls are enclosed in cabinets, the door(s) shall open at least 90 degrees or be removable. Exception: Where the enclosure requires a tool to open, and where only diagnostic and troubleshooting testing is involved on live parts operating at not over 150 volts, line-to-line, the clearances shall be permitted to be less than 2½ feet (762 mm).