ECN Forum Forums Code Related Discussion NEC & other Code issues Torque Requirements

Joe,
Does Bob have any technical data that says the cold flow effect will produce less than a 15% torque change?
Don

Joe, I knew you would email me before I got to the office this morning. I was in Joe's class (Understanding the Basics of Building Electrical Inspeciton) this week and asked the guestion, "How does one check to see if an electrical contractor torqued a termination to the manufacturers' specification?". I remembered that Bob Nolan (from my Grounding and Bonding Seminar) had made reference to a method, but I could not remember the method completely. Joe suggested that we try the website for comments. Thanks everyone for the insights you gave me. Bob, responded with his answer in the form of an email which Joe sent out to all respondents last night. Again, thanks. Joe, I have registered and look forward to many more discussions like this.

Don: no technical data, on this job the electrical engineers, contractor and myself agreed to the 15% as the torque inspection would be done about 1 hour after the installation. The system was new never energized, the torque was on bolted lugs with copper conductors, and the temperature in the area was contolled.
No one felt cold flow, thread lubricants, or differences in wreaches as something that would effect the installation or my inspection settings.
After inspecting 1100 plus terminations everyont felt the process was OK.

Bob,
Thanks. I was just wondering if there was any published data for this. I know that even without loading and temperature changes there is some cold flow over a period of time that will allow a partial turn before the original torque is reached when you check the torque. I don't think there would be much change in the one hour time frame that you were working with, but wonder about how much change there would be after a week or two.

Don(resqcapt19)