After reading at least a couple of topics elsewhere on RCDs/RCBOs etc going bang and smoking when pressing the test button, isn't the test button linked between the phase and neutral contacts internally via a high value resistor to create an imbalance?
If so, then my theory on this is the resistor probably losing it's value dramatically and going very low resistance hence when the button is pressed creating a direct short circuit - in a consumer unit RCD this would mean a short across the meter tails.........
If so, then my theory on this is the resistor probably losing it's value dramatically and going very low resistance hence when the button is pressed creating a direct short circuit - in a consumer unit RCD this would mean a short across the meter tails.........