How to isolate an earth leakage problem

[AndyD]

Don't worry about the Decabit device, it's a ripple relay that allows the supply authority to shed the load of your geyser during peak usage times. Decabit refers to the type of signal that's injected into the high voltage supply at source so it's definately a remotely operated loadshedding relay.

If you have a very old earth leakage unit or even a VOELCB then it's possible it's just nuisance tripping when there an arc. This however is fairly unlikely and the frst step is to do some insulation testing on the installation and the items that are plugged in or otherwise connected. There's little other option than to find yourself an experianced electrician who has the approprate test equipment.

[Sparks]

Fundi, you will save a lot of time and money besides the headache by following the guidelines set out from the beginning of this thread. We are qualified guys with years of experience who are trying to help. As Andy pointed out, an accumulation of faulty items can cause an excessive earth fault. Unplugging everything is a quick way to isolate a circuit with a fault. You will also note that the lighting circuits are not required to have earth leakage protection. If they are supplied through the ELCB you will need to isolate them by removing their neutral supplies one by one should the fault be on a lighting circuit. Switching the live supply off does not isolate the circuit. Your "sticky green substance" can definitely cause an earth fault big enough to trip the ELCB if it is supplied through it. Old ballasts are know to develop earth faults so they are always suspect. Any light switch, socket outlet switch or circuit breaker which does not "cleanly make and break contact" will fail compliance and needs to be replaced. You run the risk of electric shock until the day you replace those switches, the scary thing is, so does your family.

[fundi]

Fundi, you will save a lot of time and money besides the headache by following the guidelines set out from the beginning of this thread. We are qualified guys with years of experience who are trying to help. As Andy pointed out, an accumulation of faulty items can cause an excessive earth fault. Unplugging everything is a quick way to isolate a circuit with a fault. You will also note that the lighting circuits are not required to have earth leakage protection. If they are supplied through the ELCB you will need to isolate them by removing their neutral supplies one by one should the fault be on a lighting circuit. Switching the live supply off does not isolate the circuit. Your "sticky green substance" can definitely cause an earth fault big enough to trip the ELCB if it is supplied through it. Old ballasts are know to develop earth faults so they are always suspect. Any light switch, socket outlet switch or circuit breaker which does not "cleanly make and break contact" will fail compliance and needs to be replaced. You run the risk of electric shock until the day you replace those switches, the scary thing is, so does your family.

Sparks, I posted here exactly because I wanted folks like your help, otherwise I would have sought help elsewhere. So I would like to thank Leecat, AndyB and you for replying to my post. Much appreciated. I will start with the guidelines.

[Sparks]

Fundi, while the guidelines will assist you in saving time and possibly finding the fault, they are by no means all that needs to be done. Unless you are fortunate enough to find the fault using the guidelines, you will need an insulation tester/megohm meter/megger to test the final "dirty" circuit. These are not cheap testers which you can buy at the corner hardware store or hyper. They can also cause electrical shock and be lethal in the wrong hands at the wrong time. Be aware that the ELCB is the only item in the DB board which is designed for the safety of the consumer. All the other breakers are there to protect the installation. It is important that you find the fault and if need be replace the ELCB asap. It is your only watchdog against electrocution.

[fundi]

Fundi, while the guidelines will assist you in saving time and possibly finding the fault, they are by no means all that needs to be done. Unless you are fortunate enough to find the fault using the guidelines, you will need an insulation tester/megohm meter/megger to test the final "dirty" circuit. These are not cheap testers which you can buy at the corner hardware store or hyper. They can also cause electrical shock and be lethal in the wrong hands at the wrong time. Be aware that the ELCB is the only item in the DB board which is designed for the safety of the consumer. All the other breakers are there to protect the installation. It is important that you find the fault and if need be replace the ELCB asap. It is your only watchdog against electrocution.

points taken, thank you and I will report back on my findings

[ELECT 1]

There is no substitute for experience.
I have a system that i use for finding an earth leakage fault.
Its very basic, but in most cases i solve the problem.
As in IANS post, which is self explanatory .
Unplug all appliances, turnoff underfloor heating, turn off pool (by their DP isolators)
Most of the time the fault is now cleared. Then i check each appliance out that was disconnected, i megger them out. I also systematically put the pool back on, then the UFH and so on.
Now if all is disconnected and isolated, then its a Neutral. Now i remove each neutral from the bar, and more often than not its the last one that is down to earth. I have already checked the lives and they are ok.
Cut a long story short i trace out and locate the problem eventually.
The other nuisance trip is a fridge, middle of the night it usually happens, this is usually a heater in the fridge getting moisture into it.
Some times i put the fridge on a dedicated circuit. hehee.

What i cant understand, and dont have the knowledge to make a comment is why some times the earth leakage works on a .2ohm when it should trip. Any thing less than 1 Meg ohm should in theory trip. ??

[AndyD]

Any appliance with an IR reading of < 1Mohm (1 million ohms) when tested at 250 volts should be considered suspect and likely to cause problems in the near future. The earth leakage (RCD) will only trip when the total IR of all the circuits connected to it goes below 7333.3 ohms if the supply voltage is 220v.

[ELECT 1]

This is correct, BUT !!! but even some Telkom plug in transformers and surge arestors have very low IR, some times nothing trips, and all still works, but as you say, these should be disconnected from the system.

[AndyD]

Earth currents from surge arrestors aren't necessarily a fault current. If the telkom item is classII it can be supplied by a dedicated circuit and red socket which is not RCD protected. Also the test voltage used when you insulation test something with internal surge arrestors will have a big effect on the test result, especially on telecoms equipment the surge arrestor clamping voltage can be fairly low.

[fundi]

This is correct, BUT !!! but even some Telkom plug in transformers and surge arestors have very low IR, some times nothing trips, and all still works, but as you say, these should be disconnected from the system.

I know this is off topic, but we experience a lot of power surges in this area, lights dimming and brighter. These surge arrestors/protectors for televisions, are they any good?