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Maintenance Mode / ARMS - ARC Flash reduction techniques for Breaker (NG - Frame)

The breaker can be put into maintenance mode in two ways (both methods are described in the instructions of trip units 310+ type :

  1. Locally, by using a small screwdriver to turn the instantaneous setting to 2.5 or 4 times In (the instantaneous setting is boxed in the below image)

  1. Remotely, by applying a 24VDC signal using the yellow and black wires on the left side of the breaker (wiring diagram included below)

 

Maintenance mode/ARMS is a way to reduce the incident arc flash energy.

The National Electric Code (NEC) requires that breakers 1200A and larger have a means of reducing the incident arc flash energy. Maintenance mode/ARMS is one method that achieves this, and is designed to be used by personnel when they are required to perform work on energized electrical equipment (we recommend all work be done on de-energized equipment, but NFPA 70E allows this). This white paper talks about arc energy reduction techniques: https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/molded-case-circuit-breakers/power-defense-molded-case-circuit-breakers/safer-by-design-arc-energy-reduction-techniques-wp012007en1.pdf