Earth leakage trip 7 min past the hour every hour

[ians]

If you have had lightning or power surges recently, the caps could be faulty, you reset and there is no problem, but it will normally just trip randomly, not ever hour, but you never know, i have seen stranger thing happen.

[Leecatt]

Earth leakage trip 7 min past the hour every hour. How do I locate the problem? This started after I replaced the old Earth leakage. Driving me mad. The problem is on one of about 7 circuit breakers or combination of them. This tends to happen only at night, but does happen here and there during day hours.

Ok here's my 5 cents worth:
1. You have something in your circuit that is on a timer and it comes on every hour at 7 minutes past the hour for an unspecified time. Pool motor perhaps? Jaccuzzi heater?
2. This item does not produce enough "earth leakage" to trip the ELCB
3. During the night you have lights that come on, and they produce enough additional "earth leakage", which when combined with the above fault cause the ELCB to trip every time the above fault occurs.
4. During the day the lights are off but there may be additional "earth leakage" faults caused intermittently, and briefly, by other contributors such as the stove, geyser, appliances etc.

Or your neighbour is having a lot of fun at your expense...

[bergie]

the hourly tripping is weird. maybe the house is haunted.
but seriously i wouldnt look for the fault yet . install a 2nd earth leakage relay. split the circuits over both. then see what happens. in future it will also help with other fault finding. i have done this so many times and sometimes the fault doesnt come back. it could just be accumalative earth faults.

[IMHO]

bergie, I will ask my electrician to do that tomorrow. A second elcb sounds like the answer, if it will split the accumulative fault. But can it be done? All the earth wires is on one common bar, is it not?

In the meantime I have now unplugged all the laundry equipment. Still trip. Then I switched the pool pump off with its own isolator at the pump. Still trip. Now I have unplugged all fridges and freezers. Waiting for the next trip.....

[IMHO]

BTW Andy, our sparkie does not want to use the meggar. He is scared he may blow up something of mine. He is advising me to play the eliminating game, till we find the culprit.

[AndyD]

If he's got a decent mega tester there shouldn't be a problem if he uses the 250volt testing scale to test any circuits with PC's or other IT equipment.

The eliminating game would be a possibility if it was just 1 or 2 circuits causing the tripping. To play the eliminating game though you need to disconnect circuits on both the live and the neutral side, at the moment you're only disconnecting the lives when you use the breakers (MCB's) so that's where a lot of your confusing results will be coming from. RCD's (earth leakage breakers) are monitoring the live and neutral simultaneously so they can still trip to a fault on a circuit even if it's no longer live after you've knocked down the single pole breaker and this was kinda where my joke about the binary message was coming from.

The other way of monitoring actual leakage current is to use a suitably sensitive clamp meter around the live and neutral together. The current it will display is the difference between the current through the live and the current through the neutral which is basically the current leaking to earth.

A second elcb sounds like the answer, if it will split the accumulative fault. But can it be done? All the earth wires is on one common bar, is it not?

The earth wires all stay connected to the main earth bar no matter how many RCD's are installed. It's the neutrals that need to be identified and split up accordingly. Installing a second RCD isn't always plausible due to space constraints. You need enough room for the RCD itself plus enough room for an extra neutral bar.

Installing a second RCD can help if your problem is due to the cumulative effect of many small leakage faults but it can also actually highlight faults that were previously not causing problems. You need to check each circuit for borrowed or crossed neutrals otherwise it can actually cause extra complications.

[IMHO]

You need to check each circuit for borrowed or crossed neutrals otherwise it can actually cause extra complications.

Exactly what the electrician told me.

[bergie]

Exactly what the electrician told me.

its still worth doing. take the 3 easiest circuits to do.pool db,etc . if there is surfix used,then its easy to see which live and neutral go together. if its cumalative you dont have a choice.

[IMHO]

When I switch off the 6 breakers mentioned earlier, the tripping stops. It is the only way I can make it stop.


I got exited last night. I unplugged all the refrigeration. The hourly trip did not occur, but changed to 2 hourly! Damn!

Well, the electrician is on his way. Will see what he comes up with. Will subtly en quire about the 250v mega. He mention 500v, so he probably does not have the 250v unit.

[AndyD]

I got exited last night. I unplugged all the refrigeration. The hourly trip did not occur, but changed to 2 hourly! Damn!

Lol, as I stated above, just switching circuits off using the single-pole breaker doesn't work with an earth leakage fault it's just going to add to the confusion.

To play the eliminating game though you need to disconnect circuits on both the live and the neutral side, at the moment you're only disconnecting the lives when you use the breakers (MCB's) so that's where a lot of your confusing results will be coming from.

[Sparks]

As you have discovered which 6 circuits the fault originates from I suggest you remove 5 of the correspomding neutrals. If the remaining one trips you have found the faulty circuit. If not, whatever is causing the fault should immediately trip when you connect the neutrals back one at a time provided the neutrals have been disconnected for long enough.

[IMHO]

Feedback on the current status. We connected a second earth trip switch. We moved three of the six circuits to the new ELCB, which is not tripping.. The fourth is a geyser that is not on any ELCB. The fifth is the pool, which has its own ELCB at the pump, which I switched off. The sixth one is still on the old ELCB. This sixth one is feeding plugs to one area of the house. I can leave it on during day hours, but at night it trips the ELCB. Not on the hour, every hour anymore. It now takes between two and four hours. The 'sparky' will be back Monday to investigate further. At least we have narrowed it down to one breaker now. The other breakers probably still have faults, but this must be the biggest contributer.

[ians]

What were the results of the insulation resitance test on that circuit, L-N / N-E / L-E ?

What are the circuits wired with, house wire, flat twin +e, round surfix?

Do the cables run straight down the wall and have you installed cupboards or shelves or anything recently?

What is plugged into the sockets?

[IMHO]

Well, the circuit did not trip overnight!
ians, as far as your questions go, the first one I can not answer.
The wire is the round red and black wire used in DB's.
The cables goes into pipes in the wall, I suppose down.
Nothing recently installed. The problem surfaced when I replaced the old ELCB.
Plugged into the sockets is TV's and bed lamps.
This is an old problem, since more than a year ago, when I also tried to replace the old ELCB. I was unsuccessful in finding the fault and had to put the old ELCB back.

[ians]

what make of e/leakage unit did you install (new) and what make is the old unit?