Electric Power Generation, Transmission, and Distribution eTool
Disabling reclosers. Many transmission and distribution (T&D) lines and circuits use overcurrent devices (for example, breakers) with automatic reclosing devices and reclosers, which automatically reenergize a line that is deenergized by a fault. Disabling of reclosers under certain conditions is required in the "269" standard because of the increased potential hazards from electric arc, shock hazards, or burns if the recloser resets while work is being performed on energized lines or circuits.
If a line or circuit trips because of an overcurrent, the automatic recloser opens, deenergizing the line or circuit. After a preset time, the device closes again, which reenergizes the line or circuit. If the condition that caused the overcurrent is still present, the device opens again. This sequence is repeated a predetermined number of times until the condition has cleared or the device locks out.
1910.269(q)(2)(iii) requires the automatic reclosing feature to be disabled (set to non-reclosing) when conductors being installed or removed cross over energized conductors in excess of 600 volts (design features permitting).
When any live line/bare hand work is to be performed on high-voltage lines or circuits with reclosers, 1910.269(q)(3)(iv) requires that the reclosing feature be disabled (set to non-reclosing) before the work is done.
Disabling remotely operated switches. Remotely operated switches are often installed along T&D lines and circuits. A system operator in a control center or office can operate these devices to transfer heavy loads or reenergize customer lines after an outage. 1910.269(m)(3)(iii) and (iv) requires that if deenergized work is to be performed, any remote control features of switches be rendered inoperable and tagged to avoid the possibility of the unit closing (becoming energized) and to indicate that workers are at work. These devices function by radio waves and have been known to operate because of stray radio waves, thus posing an electric shock hazard.