Safety Standards

Standards for machines driven by 120v and 140v motors.

Occupational Safety & Health Administration

29 CFR #1910.213(b)(3)*: “On applications where injury to the operator might result if motors were to restart after a power failure, provisions shall be made to prevent machines from automatically restarting upon restoration of power.” *Electrical Controls for Wood Working Machinery

National Fire Protection Agency 79

Electrical Standard for Industrial Machinery, 2018 Edition

7.5.1 Voltage Supply Interruption: “Where a supply interruption or a voltage reduction can cause a hazardous condition or damage to the machine or to the work in progress, under voltage protection shall be provided (e.g., to switch off the machine) at a predetermined voltage level.”

7.5.3 Restarting: “Upon restoration of the voltage or upon switching on the incoming supply, automatic or unintentional restarting of the machine shall be prevented when such a restart causes a hazardous condition”

Annex A: A.3.3.105 Undervoltage Protection: “The principal objective of this device is to prevent automatic restarting of the equipment.”

National Electrical Code 2020

NFPA 70: NEC, International Electrical Code Series

430.43 Automatic Restarting: “A motor overload device that can restart a motor automatically after overload tripping shall not be installed if automatic restarting of the motor can result in injury to persons.”

Canadian Standards Association

Canadian Electrical Code

C22.1-98 Undervoltage Protection Required for Motors: “When automatic restarting is liable to create a hazard, the motor control device shall provide low-voltage protection.”

Part 1, 28-312 Automatic Restart after Overload: “Where automatic restarting of a motor after a shutdown on overload could cause injury to persons, the overload or overheating devices protecting the motor shall be arranged so that automatic restarting cannot occur.”