Required. An explanation of the Causes of MCB Intermittent Tripping due to Loose Connections

Hello Everybody


I wish to gain a greater knowledge as to the causes of MCB intermittent tripping due to loose connections, so any help would be greatly appreciated and the more in-depth the better as that is what I want to understand, the physics behind it.

Thermal Tripping  I can understand that a loose connection can generate heat due to resistance, IR2, and I can appreciate that it could cause an MCB to thermal trip if the loose connection is at the actual MCB Terminal (OR even an MCB either side IF THIS IS POSSIBLE) but how can a loose connection further downstream, say 8 -9 metres away cause a thermal trip.  I find it hard to believe that enough heat could dissipate far enough to reach MCB and be hot enough to trip MCB.

Magnetic Tripping  How can a loose connection cause a magnetic trip.  Intuitively I guess it must be due to arcing and arc voltages but that suggests that air is a better conductor than copper (that would also suggest that air dielectric capacitors wouldn't work I think) to allow enough Amps to flow to trip MCB or there is a sudden increase in voltage over a very short period in time dv/dt and therefore perhaps capacitance plays a part.  Basically how does an MCB magnetic trip due to a loose connection downstream?


All contributions greatly appreciated


Regards The Woodster