Isolate All Power to the Fixture

>> Mhm. And often times, even when you turn the light switch off, this is still being fed with power, right? >> Yeah. >> And you want to make sure when you work on these fixtures that you can isolate this emergency power. >> Oh. >> And one of the ways you can do it is you disassemble this switch. >> Okay? >> That's usually attached to a drop ceiling. >> And there's a disconnect inside that. >> You can you can locate these wires. And you can see here these two wires. There's a male and a female. >> Okay. >> And when these are together, this battery is actually putting out 277 volts. >> Okay. Yeah. >> Cuz we are in commercial lighting. That's the other tip. Determine are they using 120 volt or 277 volt. >> Yeah. >> Often it's 277 volt. Do you know why? Um because commercial buildings are 277 volt because uh because of the equipment they use. No, it's because the higher the voltage, the lower the current. So when we use a 480 volt panel, single pole to neutral or ground, what voltage do we read? >> Uh 120 volts. >> 277 volts. >> No, 277 volts. >> Yes. Okay. >> On a 480 vol panel, one face to ground is 277. >> Okay. >> If we use Ohm's law as 277 volts in our load calculation, our current does what? Does our current increase or decrease? When our voltage increases or decreases. >> When the when the voltage increases, the current decreases. >> Correct. So, what does that mean? uh that means uh >> we can use smaller wire or we can put more load on standard building wire. Okay. Therefore, it's always more beneficial to use 277 volt. However, getting hit by 277 volt versus 120 volt is always an issue. So, my first advice to you is don't just take the light switches off. >> Okay? Why in a commercial building? Because we're a creature of habit, right? How many times have we worked on a facility, we turn the power off, but