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Ask Any Electrician if Tight Connections are Important, and the Answer Will Be Yes.

Ask almost any electrician or maintenance tech how to check if a connection is tight, and you probably won’t get the correct answer. In fact, it’s a trick question.

The only time you can check the tightness of a connection is when you make the connection. The reason is the mechanical physics involved.

A bolt obtains maximum clamping power when it’s stretched to the upper limit of its “elastic limit.” Stretching it more just reduces its clamping power. When you “retighten” a bolt, you actually make the connection weaker.

What if you loosen a bolt, then tighten it? Unfortunately, that initial tightening resulted in “strain,” which means the elastic limit of the bolt will significantly decrease (typically, by 50%) as soon as the bolt is relaxed. That’s why you don’t re-use fasteners on critical connections.

What if you just check the bolt with a torque wrench? Two problems:

  1. You must exceed the specified torque to “break” the wrench.
  2. The published torque tables are generic and rely on assumptions that may not apply to your application.

To see which connections need replacing, you have two methods:

  1. Conduct a thermographic scan while things are energized.
  2. Conduct resistance tests across the connection using a high ohms meter at nominal voltage (don’t use a 9V DMM for this test).

Final tip: To tighten new busbar fasteners, use the torque values for that particular hardware kit.

Source: Mark Lamendola | Mindconnection