ELCB problem

[tekee]

I am having problems with my ELCB randomly tripping. I have had the ELCB tested when I had a new kitchen installed and all was tested ok. However, it keeps tripping normally more in the evenings but can be during the day as well. I have tried to see if there is a pattern to when it trip e.g. things turning on/off or specific times etc., but have not been able to find anything.

I also have an earth pipe instead of earth to mains, but I don’t think that would have any relevance to the problem. I’m not sure where to start as there’s no obvious appliances showing faults.

I thought about investing on a single ELCB that I could plug each appliance into and see if that tripped at the same time as the main ELCB, however, that wouldn’t work very well for things directly wired into the system e.g. cookers etc.

I looked at a similar thread posted earlier but that appeared to be connected to water leakage problems, unfortunately my trip happens in the dry as well !

Any idea’s to get me going would be appreciated.

Thanks in advance.

 

[Skogsgurra]

This sounds like it could be a VFD problem. VFDs have high switching frequencies and cause a great deal of HF stray current leaking thriugh cable capacitance and motor/ground capacitance.

The ELCB (I prefer RCD*) cannot distinguish between those capacitive currents and "true" earth leakage. Look for VFDs, they can be anywhere. Speed controlled fans and pumps, washing machines, dryers, refrigerators are some possible places where you find them. Also, some dimmers can give you this problem. But that is unusual.

*Earth Leakage Circuit Breaker is actually a lot better than Residual Current Device, but most guys tend to use the TLA instead of the FLA nowadays.

Gunnar Englund

http://www.gke.org

 

[waross]

First step;
Try to cycle your appliances on and off to locate the source of the problem. You mentioned your kitchen. You may have a heating element failing. You may be able to find a "leaky" element by checking each one to ground with a multimeter. If you can find one or more elements with ground leakage that is probably the problem. If you don't find a problem with a multi meter, don't assume the elements are good until they are checked with a megger.
Depending on the switching, the heating elements on a stove may only have excess leakage at some but not all switch settings. To make the problem more random, you may have leakage from more than one element so that the ELCB only trips when two elements are in use at particular switch settings.
Another way you may be able to test is to put a very small light bulb in series with the ground connections of the appliances one by one, and check the voltage across the light bulb.
You may also use a resistor instead of a lamp for testing.
The voltage measured across the lamp or resistor divided by the resistance of the lamp or resistor will equal the leakage current.
If you suspect that your ground connection may not be dependable, you may try running a ground wire from the mains ground in the panel to each appliance for testing. This is a good idea for testing in any event.
Make a few tests and let us know what you find.
yours

 

[matwong]

I'll suspect the leakage current from neutral to ground. Firstly, you may check all cables of your electric appliances, eg. kettle, fridge, heater, oven etc whether there is any damage. Next, you may check on all the connection at the sockets or appliances end to confirm the condition is still good. Lastly, you may seek the internal wiring contractor's help to verify the extension work that they have done is perfectly done.