Nortel 7400 Hardware Installation page 523

Procedure steps
1 Toggle on the appropriate circuit breaker at the power source that feeds
each power supply that was turned off.
2 Toggle to the on position the power control on the power supply.
The LED on the power supply of a Nortel Networks Multiservice
Switch 7460 device lights green to indicate power is on. Unlit means the
power source is still off.
Multiservice Switch 7400 Hardware Installation, Maintenance, and Upgrade 6.1S2
Chapter 39 Hardware procedures 523