Meh, for 120V or 220V worst can happen is you get a little shock or trip the breakers. I don't bother shutting off power to household circuits either.
I heard from HV vets that one acquires a habit of keeping one hand in the back pocket when working on substations, industrial installations, and such. :-)
Not sure where there would be 300V for light switches/fixtures though. Some bespoke factory setup?
The lights were using some higher voltage. The Operations Manager mentioned it to me, while the work was being done. Apparently, it's standard. Something like 320 volts (don't remember the exact number). I had not heard of it, beforehand.
230V AC is the RMS (root mean square) voltage; if you rectify it to DC, it comes out to 325V. Put another way, the /highest/ absolute potential difference between line and neutral in a 230VAC system is 325V.
I heard from HV vets that one acquires a habit of keeping one hand in the back pocket when working on substations, industrial installations, and such. :-)
Not sure where there would be 300V for light switches/fixtures though. Some bespoke factory setup?