As a surveyor in the construction industry (and having worked in both imperial and metric in the UK, the US, Canada and South Africa), something about this story doesn't quite ring true.
1. In-the-field tolerances are never less than 1/16" imperial (1.6 mm), or 1 mm metric (at least I've never come across tolerances tighter than that, and that includes a lot of precision hospital work). The 2/100ths of an inch is almost exactly 0.5 mm, a tolerance virtually impossible to achieve on a construction site. 2. The 2.52" is almost exactly 64 mm. Allowing for a tolerance of say +/- 1 mm, the trench should have been specified at 65 mm. 3. I'm no electrical expert, but I do know that cables when conducting electricity heat up and expand. Was no allowance made for this? And would it not have been wise to allow a tiny bit of airpace between the cable and trench walls to allow air circulation and help the cable to stay cool(er)? I wonder if there's more to this story than is being told? Cheers John F-L ----- Original Message ----- From: ezra.steinb...@comcast.net To: U.S. Metric Association Sent: Thursday, August 06, 2009 12:07 AM Subject: [USMA:45529] I blew it! (The conversion of 2/100ths of an inch, that is) OK, I got my conversion wrong. But I bet we would be using whole numbers in millimiters if we were using and familiar with metric and had adopted millimeters for construction as Pat has observed works best in industry. -- Ezra
