strange tripping problem

[homesolutions]

dear all

 

would appreciate your advice on the following

 

my electrical supply was running well for about 2 months before it started to give problems

 

the water heater started to trip after operating for maybe 10 minutes on a rainy day

 

the tripping time decreased while the frequency increased. now it trips immediately upon starting so i have disconnected it(both the live and neutral wire)

 

then the kettle started tripping after about 10 minutes. then the iron, also after about the same time.

 

the water heater(now disconnected) was on a separate mcb, the kettle was on shared mcb with the microwave, the iron was on a shared mcb with the fridge.

 

the tripping occurs with almost no load, except maybe the water pump, light circuit and the TV on standby.

 

there is no problem with the microwave, washer, fridge and TV during operation, except sometimes the main breaker trips when nothing is turned on but on standby(MCB is on but appliance is not operating)

 

today the iron tripped again after about 10minutes. i have tried running a new earth wire but the problem remains.

 

I measured the voltage it shows Live to Earth 225V, Live to Neutral 223V, Neutral to Earth 0V

 

the main breaker which trips has both a Live and Neutral connection so when it trips the neutral wire is disconnected too.

 

thank you

 

 

[bankruatsteve]

A photo of your breaker box would help.  Is the main breaker RCBO? What are the amp ratings for the breakers?  It sounds like you have at least 2-3 circuits on separate breakers.  Do the individual breakers trip or only the main?  What is your meter rating?  What size wire from meter to your CU?  What size wire for your sockets?  Within the 2 months, what changed?  IE: did you add a shower unit or new construction?  

[homesolutions]

yes the main breaker is rcbo. it is 125A.

 

individual breakers range from 10A(light) to 40A(water heater).

 

only the main breaker trips, not the individuals.

 

meter rating is 30/100.

 

wire size from meter to CU 25mm2.

 

wire size for socket 2.5mm2-4mm2

 

nothing changed except for the weather(more rain) during the 2 months. and the 1st trip occurred during rainy weather. so i thought it had something to do with the earth wire not being connected properly, or rain water entering the circuit.

 

but the trips started occurring during dry weather as well, and mainly to appliances which has a heating element(water heater, kettle, iron). however the circuit can be restarted immediately by disconnecting the problem appliance, like the iron or kettle, so water in the circuit is also excluded

 

 

[bankruatsteve]

Then you probably have N-E fault or L-E fault on one or more of your circuits and/or appliance that is activated by high humidity and/or ants/bugs/dust/gecko eggs.  If a trip can be isolated to a single appliance, then give it a good clean, look for bugs, dust, etc. which may require taking things apart. If tripping occurs without appliance 'on', then check sockets for ants, bugs, dust, etc.  It's got to be something like that.

[Crossy]

RCD / RCBO tripping on load is a classic N-E fault scenario, possibly exacerbated by the damp weather improving your ground connection.

 

Finding it may be fun.

 

Try this.

1. With the power off and all breakers open disconnect all the neutrals from the neutral bar, unplug all appliances and turn off all light switches.
2. Then, with your meter on the highest resistance range it does, check each neutral to the grounds still in the ground bar.
3. With luck you should find one that's a lot lower than all the others.
4. Put the neutrals back except the low resistance one (insulate the end with some tape).
5. Turn the power back on and see if you still get a trip
6. Assuming you don't, investigate the circuit you've disconnected

Hopefully the fault is low enough resistance to show on a normal meter, otherwise you'll be needing an insulation tester :(

 

 

 

[IMHO]

Do you have any 220V garden lights, outdoor sockets, or any other lines going to outdoors?

 

If yes, isolate the breakers for these first than see if it helps.. switches only cut the active line - if water has got into these, you can still get a neutral to earth fault even if switched off.

[homesolutions]

RCD / RCBO tripping on load is a classic N-E fault scenario, possibly exacerbated by the damp weather improving your ground connection.

 

Finding it may be fun.

 

Try this.

1. With the power off and all breakers open disconnect all the neutrals from the neutral bar, unplug all appliances and turn off all light switches.
2. Then, with your meter on the highest resistance range it does, check each neutral to the grounds still in the ground bar.
3. With luck you should find one that's a lot lower than all the others.
4. Put the neutrals back except the low resistance one (insulate the end with some tape).
5. Turn the power back on and see if you still get a trip
6. Assuming you don't, investigate the circuit you've disconnected

Hopefully the fault is low enough resistance to show on a normal meter, otherwise you'll be needing an insulation tester

 

thanks will try it out tomorrow and report back on the progress

 

 

 

[RichCor]

My 'guess' is that your main RCBO is failing and opening under a normal load.  

 

If Crossy's tests don't have you locating a resistance with all the wires pulled from their terminals then try putting in a new RCBO.

 

Can you post pictures?

[homesolutions]

problem solved

 

i have gained from the experience and thanks to all post contributors

[Crossy]

problem solved

 

i have gained from the experience and thanks to all post contributors

 

Come on, spill the beans, what was the problem?

 

Seriously, we don't bite and the information may be good for others with similar issues.
 

[Forkinhades]

RCD / RCBO tripping on load is a classic N-E fault scenario, possibly exacerbated by the damp weather improving your ground connection.

 

Finding it may be fun.

 

Try this.

1. With the power off and all breakers open disconnect all the neutrals from the neutral bar, unplug all appliances and turn off all light switches.
2. Then, with your meter on the highest resistance range it does, check each neutral to the grounds still in the ground bar.
3. With luck you should find one that's a lot lower than all the others.
4. Put the neutrals back except the low resistance one (insulate the end with some tape).
5. Turn the power back on and see if you still get a trip
6. Assuming you don't, investigate the circuit you've disconnected

Hopefully the fault is low enough resistance to show on a normal meter, otherwise you'll be needing an insulation tester

 

 

 

 

 

Just to add that the switches should be in the 'on' position otherwise that part of the circuitry will not be tested. Water ingress in light fixtures can be a good culprit of this type of fault, and it can be a build up of 'high' resistances on several fixtures, and when added together will cause the Safe-t-cut to open. 

A DMM will only pick up 'dead shorts', and not the high resistances that water tracking can have in fixtures.

Other than that it could be degradation of insulation covering the cable that could have maybe a 'fault' of 10K ohms on it between conductors. Which on its own is not enough to open the safe-t-cut, but with another appliance plugged in and switched on will open the Safe-t-cut.

[Forkinhades]

 

problem solved

 

i have gained from the experience and thanks to all post contributors

 

Come on, spill the beans, what was the problem?

 

Seriously, we don't bite and the information may be good for others with similar issues.
 

 

 

Yes a reply would be good

[Forkinhades]

^ Point to add as well, the 'fault' could be on the 'live' 'hot' 'phase' cable as well, and these should be tested to earth also.

[wayned]

Don't you just love these guys that post a weird problem and ask for help and then tell you it's solved but not what the problem was.  When you ask they go silent!

[Artisi]

Don't you just love these guys that post a weird problem and ask for help and then tell you it's solved but not what the problem was.  When you ask they go silent!

Maybe from embarrassment resulting from something stupid on their part.