I found an interesting web page about a 50 AMP service tester and decided to build myself one... The
page I found has a great explanation of how it works. It was also something I could build, using only a couple of tools and while sitting in my recliner. Here's a picture of my new 50 AMP tester....
BTW: I made a 30 AMP tester a couple of years ago and it's now available... The flashlight, voltmeter and the polarity tester aren't included... The flashlight stays in my garage and the meter/tester are being used on the new 50 AMP tester...