Skip to main content
Electronic Theatre Controls Inc

ArcSystem Emergency Sense and Maintained Inputs Must be Supplied from the Same Phase

The installation documentation for ArcSystem fixtures and drivers carries the following warning:

Important-Icon.png WARNING: Sense (normal) and Maintained (normal/emergency) feeds must have the same phase.


The Maintained and Sense lines must be provided by the same phase in order for a driver to properly track emergency state.

Consider the following scenario: an ArcSystem fixture's maintained line is powered from an SC1008 which handles switching the power from a normal source--on phase A--to an emergency source when normal power is lost. However, its normal sense line is powered from a breaker on phase B. In this case, if only phase A fails due to an errant rodent chewing through a feeder, the SC1008 will do its job and switch the power for the driver to the emergency source. If the normal phase B stays energized, the driver will detect that and remain in normal mode, which could present a life safety risk. The only way that the driver can detect a partial power failure which affects it is to have the sense line come from the same phase as its maintained line.

Related Links/References

  • Was this article helpful?