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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

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0 The Woodster over 5 years ago

Wi Fi Router not Woodworking router. Installation had no problems until the face plates on three sockets were changed and a new spurred socket added, with reversed polarity. On two of three face plates that were changed, either the line or the neutral terminals were loose. The wi fi router was the only thing plugged into the reversed polarity spur and was left on constantly obviously. Ever since MCB intermittently trips but not before any of the above changes.

Loose connections rectified and socket polarity corrected, problem disappeared. BUT which of the faults was the culprit causing intermittent tripping of MCB. I have known about loose connections causing problems and have had my own theories and guess I wanted to ask the forum about the physics behind the phenomenon. Just about the only challenge I find with Domestic Electrics is fault finding, it helps to relief the boredom of fitting ext fans and cookers and PIR sensors and switches and sockets and .....

I used to be a Software Engineer and loved debugging until retraining at the ripe old age of 42 to be a Spark following redundancy.

The Woodster
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0 The Woodster over 5 years ago

Wi Fi Router not Woodworking router. Installation had no problems until the face plates on three sockets were changed and a new spurred socket added, with reversed polarity. On two of three face plates that were changed, either the line or the neutral terminals were loose. The wi fi router was the only thing plugged into the reversed polarity spur and was left on constantly obviously. Ever since MCB intermittently trips but not before any of the above changes.

Loose connections rectified and socket polarity corrected, problem disappeared. BUT which of the faults was the culprit causing intermittent tripping of MCB. I have known about loose connections causing problems and have had my own theories and guess I wanted to ask the forum about the physics behind the phenomenon. Just about the only challenge I find with Domestic Electrics is fault finding, it helps to relief the boredom of fitting ext fans and cookers and PIR sensors and switches and sockets and .....

I used to be a Software Engineer and loved debugging until retraining at the ripe old age of 42 to be a Spark following redundancy.

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

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