Updating to circuit breakers
The stab is the part that connects to the buss bar through spring tension.It is the most common point of failure and also the hardest to detect because it is on the back side of the breaker and can only be seen if removed.Some are bolted into place and others slide or snap in like smaller breakers.
To verify that your breaker is working properly you will need to measure the voltage on both sides of your breaker known as line and load.The line side will be live even if the breaker is shut off, so be careful.A reading of about 240 volts should be measured between the two line side feeders.When this spring tension weakens the connection becomes loose and heat, sparking and burning can occur damaging your panel’s buss bar.If the stab on your breaker is failing timely repairs are important because as the arcing and burning continues there is more damage being done to your buss bar.
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Often times there will be signs that your main breaker is about to fail and other times they just completely fail without warning.