I was on a show recently when I was asked to look at the electrical supply and find out whether there was enough overhead to expand the lighting system in the coming years. Since I was the lighting director and not the electrician on this particular gig, I didn't have my tools with me, so I asked the head electrician to help. When I saw his meter, I asked him if it was a true RMS meter. It wasn't. Oh no! We took readings but without a true RMS meter, there's no sure way to tell how accurate they were. So I wrote this article about meters: