I was working in an office building in Providence and was asked by a customer to install a recepteacle for another computer. I looked above the suspended ceiling snd saw a 4 square no markings so I snaked a new circuit cut in a box & put in the receptacle. Lastly I tied in the new black & white to the existing black & white. But when I plugged in the new computer poof! Then I checked with my meter 277!
