When you are checking a unit of any kind you should be keeping your eyes open for signs of arcing and melting at all of your wire connections and contact points. We find issues with melting terminals on contactors and in disconnects regularly, but rarely do we think about the relationship between circuit ampacity and wire size and the connections to our equipment.
First, consider the fact that a #10 wire doesn’t always have an ampacity of 30 amps, it has an ampacity of 30 amps with a 60° Celsius rated assembly at 30° Celsius ambient.
The wire (conductor) is rated at 90° and the contactor is rated at 75° when torqued down to 22 in/lbs on screw type terminals and 40 in/lbs on lug type.
So the entire assembly is only as good as the weakest link and the weakest link is the terminals and the terminals are only as good as the contact they are making.
Conclusion: The termination points are usually the weakest point of the circuit
When sizing conductors don’t forget ALL of the termination points. From the breaker to the disconnect to the unit, every termination point should be properly connected and the rating checked if you intend to use any ampacity other than 60° Celsius.
Check those terminations.
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