How to isolate an earth leakage problem

[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?

[AndyD]

Dimming lights is probably caused by voltage dips during peak load times. This is completely different to surges. Surge arrestors won't help protect against voltage dips I'm afraid.

Most decent electronic items have their own built-in surge protection, if you're living in an area that's notorious for lightning strikes then supplimentary surge protection can't hurt but look at protecting the entire installation by having them installed in your DB rather than just protecting individual appliances with a 'piggy-back' type unit at the plug.

[fundi]

Step 1 : switch off the main switch, earth leakage unit and all the circuit breakers, unplug everything and switch off isolators (stoves, pool, geyser, etc)

Step 2 : switch on the earth leakage unit first then switch on the main switch, if the earth leakage trips chances are you have a neutral fault, you need to call an electrician. If the earth leakage unit stays up/on go to step 3

Step 3 : Switch on one circuit breaker at a time and wait a second or 2 as you switch them on, if the earth leakage trips as you switch on a circuit breaker, leave the circuit breaker down/off and move to the next circuit breaker, if the rest of the circuit breakers are reset without tripping the earth leakage unit then you have identified the circuit then you can start plugging appliance back in and switching on isolators, you will find some appliance don't work, you will need to get an electrician to trace the fault. If all the circuit breakers reset without tripping the earth leakage unit, then go to step 4

Step 4 : Start plugging in appliances and switch on isolators one at a time until the cable/ appliance trips the earth leakage, unplug the appliance which trips the earth leakage and leave it unplugged, you have identified the problem, you don't need to call an electrician, just replace the appliance, if you switch on the pool isolator and it trips the earth leakage you know it is the pool causing the problem.

Note!!!!
This is a very basic explanation of what might be causing the earth leakage unit trip and if in doubt call your local electrician.
Finding an "electrician" capable of tracing faults could be just as tricky as the fault itself

I have followed the steps above. First time the EL tripped was when I plugged back in the power to my gate motor/lights
So the potential culprits seems to be my gate motor and/or two lights at my gate which are switched on/off by a light sensor positioned back at the house and wired into the power cable going to the gate.
I left that unplugged and when I reset the EL it stayed up first time whereas previously I had to do it a few times.

[fundi]

I have followed the steps above. First time the EL tripped was when I plugged back in the power to my gate motor/lights
So the potential culprits seems to be my gate motor and/or two lights at my gate which are switched on/off by a light sensor positioned back at the house and wired into the power cable going to the gate.
I left that unplugged and when I reset the EL it stayed up first time whereas previously I had to do it a few times.

sorry forgot to mention the gate plug was the last one to be plugged in as it is in my garage.

[F.Viljoen]

If only the 2 lights at the gate are controlled by the photocell, good. If your gate motor is also controlled by it, that 7aH battery is not going to last long.

[Sparks]

Why have lights @ the gate controlled by a switch @ the back of the house? Mount the switch by the gate. You can get power from the motor, you also have the option of having the gate switching the lights on when it opens, if you do not require the lights to burn all night. This way you will be aware of your gate opening at night by someone other than yourself.

[fundi]

Why have lights @ the gate controlled by a switch @ the back of the house? Mount the switch by the gate. You can get power from the motor, you also have the option of having the gate switching the lights on when it opens, if you do not require the lights to burn all night. This way you will be aware of your gate opening at night by someone other than yourself.

I said back at the house, not at the back of the house, it's actually positioned at the front of the house, but it's a good idea you have, thank u. I actually would prefer the lights not to be on all night as I have a municipal one right at my entrance.

[Kevlaz01]

I've done as prescribed and I have located one circuit to be suspect, problem is, I have no appliance connected to any of the plugs

[Sparks]

Do you have and extension or multiplug plugged in? Is it a mixed circuit with outside lights on it? Does the circuit go outside? Is there a joint outside? Did you have rain just before it tripped? Was a plug changed recently? These questions will also help identify the fault.

[Kevlaz01]

I have disconnected everything and switched the CB off. Weird thing, after I disconnected the feed to the plugs and reconnected, the breaker tripped once and a after I reset the EL it stayed on until now. So it is working but I'm still baffled as to what caused the EL trip in the first place, but thanx for your input.

[MullerR]

Hi Everyone. Im new to the Forum. I am also an Electrician, not long in the trade, so Im still learning alot from experienced guys. I sit with a very confusing problem regarding an earth leakage device. The earth leakage will trip for no apparent reason anytime of the day and when I switch it back on again, it trips instantly. When I switch off the plugs circuits, it switches on again and then I can Switch on again the plug circuits. The Unit trips when pressing the test button, BUT when I do a test with the ELCB tester, it does not trip. In the kitchen is a ready board, feeding from the main DB with an earth leakage and that one trips when testing with the push button and the ELCB Tester. In the garage is also an Earth Leakage device which operates 100% correct. So I changed the Earth Leakage in the house with the one in the garage, cause I though maybe the one in the house is faulty, but it still does the same, does not want to trip when testing with ELCB tester and the one in the garage still work 100%. What can the cause be that it does not want to trip when testing with ELCB tester, but it trips randomly for no reason?