Al's Annual Inspection Thread 2015

[Mr V]

Circuit breakers are circuit protection devices, that means they exist to protect the wire. What they protect the wire from is the insulation getting so hot it melts. There are many types of insulation with many different melting points and the rating for the wire and insulation is dependent on the conditions it is used in. That means there is no universal rating for say a 12ga wire. The CIM wires enter the motor where the temps will be much higher than ambient. Because of that they use high temp insulation which means that particular 14ga wire can safely carry a 40a load.

It is not practical for all inspectors to be trained to identify all types of insulation, know their temp ratings and to have to check the type of insulation on a robot by robot basis. So FIRST makes the assumption that a motor MFG knows what they are doing when they selected the attached wire and that the average team will be using wire with low temp insulation and set the rules accordingly.