Originally Posted by michael m
i know that, but when your working in a computer lab in the floor a plug-in tester would be faster
That part when you describe computer lab and you mention 208 volts this is a very good chance that is a commercal building and the best answer is have the electrician to do this.
The reason why due that a very good chance you may have triphase supply in there and it have to be balanced properly so the electrician can able sort it out very quick.
I have my own tester for this purpose but it for myself only.