When are low-voltage control equipment, relays, motors and the like permitted to be installed in compartments with exposed high-voltage energized parts or high-voltage wiring with respect to equipment that is operating at over 600V?

  1. When the access means is interlocked with the high-voltage switch or disconnecting means to prevent the access means from being opened or removed.
  2. When the high-voltage switch or disconnecting means is in the isolating position.
  3. Option A or B is permitted
  4. It is never permitted to do this in applications over 600V nominal

Answer: C

As noted in 490.35(B), "Low-voltage control equipment, relays, motors and the like shall not be installed in compartments with exposed high-voltage energized parts or high-voltage wiring unless either of the following conditions is met:

  1. The access means is interlocked with the high-voltage switch or disconnecting means to prevent the access means from being opened or removed.
  2. The high-voltage switch or disconnecting means is in the isolating position.

Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at necexpert@aol.com.