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Ebook Industrial control panels for the north american market: Part 2

(BQ) Part 1 book "Industrial control panels for the north american market" has contents: Supply circuit disconnecting device, configuring and sizing combination motor controllers according to UL 508A, device selection according to technical data, device selection, color coding of conductors in the power circuit,.and other contents. | 6 Devices 6.1 Supply circuit disconnecting device (Main Disconnecting Means) 6.1.1 Regulations for the main disconnecting means Systems according to NFPA In accordance with NFPA 79 Chapter 5 and UL 508A Art. 30: Each system shall be fitted with a main disconnecting means. Two or more main disconnecting means shall be installed where there are two or more systems. The main disconnecting means shall switch off all electric circuits, including the control circuits. Exception: Separate circuits such as service receptacles and panel lighting. Main disconnecting means General: In the USA, it is standard practice to design the devices and cables from the load upwards. The main disconnecting means can be fitted in the industrial control panel, or the panel is provided with a label stating that a main disconnecting means needs to be connected upstream during installation. All the devices used shall be approved. If there is no need to safely shut down (isolate) other industrial control panels for maintenance and repair purposes, no other disconnecting means need to be installed. However if the individual panels need to be switched off separately, the industrial control equipment referred to under sub-part 6.1.2 can be used. A redundantly driven magnetic controller with an electrical interlock can also be used if it is approved (listed) for this isolating function. NFPA 79 Chapter 5.5.4 (3) For systems with 2 hp or less, the main disconnecting means may be fitted at a distance of not more than 6 m (20 ft), provided that it is visible and can be easily reached. Regulations, approvals, structure Country-specific Documentation, Version 11/2010, A5E02118900-01 121 Devices 6.1 Supply circuit disconnecting device EMERGENCY STOP If main disconnecting means are used as emergency stop switches, these shall: (NFPA 79 Chapter 10.7.5) ● Be visible and easy to access, ● The operating handle shall be red and the background around the handle shall be yellow, ● The switch shall be