Hi Ben; I'll put in my $0.02. Having been an industrial electrician for a couple of years back in the 1970's I might know a thing or two. I worked in a wire drawing mill where 208 Y and 480 Y 3 phase were common voltages we worked with every day. If you want to discuss more info on the project you are working on, feel free to contact me off list. My only caution is to insure safe signal return commons to the power lines you are working on, along with proper insulation of your phase line current transformers. Depending on how the power is brought into your facility, and how old the facility is, the grounds can be VERY ratty!!! Although I am not trying to volunteer him, Bill Dromgoole may be another resource to contact as he just made up a breadboard to load up the 3 phase 400 cyle MG set for the Univac targeting computer. That shipboard power was part of his "bread & butter" when he was working. Bill Inderrieden In a message dated 7/11/2017 12:02:05 P.M. Eastern Daylight Time, vcf-midatlantic-request@lists.vintagecomputerfederation.org writes: Message: 2 Date: Mon, 10 Jul 2017 14:01:01 -0400 From: Ben Greenfield <ben@cogs.com> To: vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> Cc: Herb Johnson <hjohnson@retrotechnology.info> Subject: Re: [vcf-midatlantic] Off topic-testing 3 phase power Message-ID: <850FDE4F-74C2-471D-A3C4-BF8A74D9C38E@cogs.com> Content-Type: text/plain; charset=utf-8 Hey Herb, The only thing I can say in my defense is that one can be both naive and have respect for electricity. As for a professional, I have one involved. Unfortunately my natural curiorsity keeps me from being passive during integration of this project. I could have gotten into all sorts of esoteric details about what I?m really trying to troubleshoot but I really wanted a simple answer, which I got from Bill Dudley. Bill?s answer was simple and re-enforced my beliefs on the subject. Regarding testing equipment. I believe the Fluke I referenced was proper testing equipment and I wanted to see what others thought. I included a link to it?s page it is rugged 4 channel 100 Mhz portable oscilloscope. This looks like the ultimate tool for this type of work and I wanted to know what other?s thought. http://en-us.fluke.com/products/portable-oscilloscopes/fluke-190-ii-portable -oscilloscope-190-104.html I followed list guidelines by marking the post off-topic. I felt it was a fair question in a hacker environment and I thought others may have first hand experience they could share. I was satisfied with answers I did receive and I love that the list exists as resource for hacking questions for all sorts of technology. Thanks, Ben