---
title: Automatic Transfer Switches
…352 unchanged lines
### The power switching mechanism shall be a single, integrated double-throw device — not two independent breakers tied together by an external interlock.
−### Mechanical interlocking shall prevent simultaneous connection of both sources to the load, except in closed-transition operation, where overlapping connection is permitted for a controlled, brief interval (see [[#Transfer Type]] below).
+### Mechanical interlocking shall prevent simultaneous connection of both sources to the load, except in closed-transition operation, where overlapping connection is permitted for a controlled, brief interval (see the Transfer Type requirements below).
### The switching contacts shall be silver-alloy, designed for the inrush and interrupting duty associated with the connected load, and shall be inspectable and replaceable as a field-serviceable assembly.
…652 unchanged lines
## Spare parts shall be stored in a clearly labeled cabinet or container in the electrical room or generator room, accessible to maintenance personnel without specialized tools.