Static Transfer Switch Safety Configuration

Friend,

A static switch is basically electronic semiconductors connected so the transition from off-on (or on-off) takes place in milliseconds or even less time. All semiconductors have some residual leakage, which is frequently dissipated through a properly-sized resistor. You must assume that the "off" side of a static switch is live at all times. I suspect that nearby live terminals exist.

"Can I work safely on the one input of static transfer switch..." Only under some very limited conditions as identified in the 2018 NFPA 70E Standard for Electrical Safety in the Workplace. It specifies six steps to be taken to minimize risk: Elimination, Substitution, Engineering Controls, Awareness, Administrative Controls, and Personal Protective Equipment. In Article 130(A)(2) it says: "Energized work shall be permitted where the employer can demonstrate that the task to be performed is infeasible in a de-energized state due to equipment design or operational limitations." If you are going to work on energized equipment then you must fill out an energized work permit and get it signed by the people doing the work and management (not just your boss). A few exceptions exist to this but I'll leave you to decide if any of them apply (see 130.2(B)(3)).

As others have already said, insist on working safely. If the supervisor or boss says to proceed then, if the exceptions do not apply, fill out the permit, have them sign it, and provide you with the necessary PPE. Accidents will happen and some of the results from them are lethal or life-changing.

--JMM