Measuring Circuit Breaker Trip Bar Force

In NFPA 70B Table 15.3.4 MCCB,ICCB, and LVPCB Mechanical Servicing, No.5 task states:

Measuring and recording TRIP BAR FORCE. This being an " offline enhanced test"

Now the question: What is this test? and why can I not find it anywhere in terms of how to perform it.

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I can definitely think of a way to measure the force it takes to operate the trip bar. I think this test is only pertinent for refurbished/repaired breakers or breakers that have had trip mechanism issues.
Something as simple as a Digital Newton Meter
can be used. I don’t have any experience with this meter but wanted to reference something to look at.


This is good, a place to start! thank you for your input.

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Do they give you any information on acceptable results? Seems like the Newton meter is what you need, I found this excerpt from a Digitrip Retrofit manual for ITE LG breakers (IL 33-LGH-1):

Measure the force necessary to trip the Breaker at the point where the Trip Shaft contacts the Trip Finger on the Direct Trip Actuator. The force necessary to trip the Breaker MUST NOT EXCEED THREE (3) lbs.

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