Mains circuit breaker occasionally trips

[laislica]

We live in a two story house, end of terrace in a moobaan.

It's maybe 5 years old and was the show house.

Once every few months the main circuit breaker trips for no apparent reason.

Resetting the breaker sorts the problem.

Strange- what could the problem be?

It just happened again this evening.

Not been raining.

Only one aircon running in a bedroom and not hard at that, set to 27 degrees (not likely to be the problem, see below)..

No TV on.

A couple of lights and the fridge plus this laptop.

We did have a t-cut fitted but they would not install the earth!

(Thai electricity not same as in your home country LOL)

I did find out that the aircons are in fact wired to the mains Before the main CB.....

When we return next year, I would like the whole house to be rewired, all sockets to have an earth.....

We sometimes hear noises coming from the downstairs ceiling space like lizards running about but tonight, no noises.

Any ideas would be welcome.

[cheeryble]

There may be a sensitivity adjustment knob on the box.

[Crossy]

It could be one of a dozen things.

Does the breaker that trips have a 'Test' button (is it an RCD / RCBO)?

What current rating is it?

What meter rating do you have (the meter will be marked 5/15, 15/45, 30/100).

Post photos if you're not sure.

[lopburi3]

Did you say you have a Safe-t-cut installed? They do not require a ground to operate so if that is the breaker that trips it is likely a momentary short to ground causing it - they normally have adjustable sensitivity and 5ma lowest setting is often a problem - 15-20-30 settings should still protect life and likely be more reliable (you do not want power loss when out of home to spoil freezer items).

And yes a re-wire is in order and get those air conditioners on the downside of your main breaker. Can not believe they are still doing this only five years ago - know they did several decades ago.

.

[laislica]

It could be one of a dozen things.

Does the breaker that trips have a 'Test' button (is it an RCD / RCBO)? NO

What current rating is it?

What meter rating do you have (the meter will be marked 5/15, 15/45, 30/100).

Post photos if you're not sure.

The main breaker The twin on the right was open.

I closed it and Bang.

Then I opened all breakers and t cut.

Closed t cut

Closed the twin

Closed the singles, first left, then right.

Everything works, no further fault.

[laislica]

Did you say you have a Safe-t-cut installed? They do not require a ground to operate so if that is the breaker that trips it is likely a momentary short to ground causing it - they normally have adjustable sensitivity and 5ma lowest setting is often a problem - 15-20-30 settings should still protect life and likely be more reliable (you do not want power loss when out of home to spoil freezer items).

And yes a re-wire is in order and get those air conditioners on the downside of your main breaker. Can not believe they are still doing this only five years ago - know they did several decades ago.

.

It's not the T Cut tripping but the main breaker.

[lopburi3]

That main breaker at 40 amps is too small for the meter you are using and probably the reason they wired air conditioners before it.

[Crossy]

That main breaker at 40 amps is too small for the meter you are using and probably the reason they wired air conditioners before it.

True, but something pretty Watty or faulty is causing it to open.

Since it's not opening on earth leakage I'd be looking for bad joints fizzing quietly away in some dark place (yup, it's going to be a nightmare).

It's also possible that the breaker itself is faulty, simple 2-pole MCBs are cheap could be worth swapping it out for a 50A unit (to suit your 15/45 meter).

EDIT. I see you note that there was a bang when you closed the breaker. You need to locate the source of the bang, gekko or rat across the supply (now blown off) is a good bet, perhaps that's why the scurrying has stopped.

[cheeryble]

Instead of getting a "bang" from the breaker as you turn it on (you might be holding it slightly in the ON position and dam again it?) next time maybe better to switch all electrics around the house off then turn on breaker then turn on outlets/switches around the house one by one.

Might learn something too.

[IMHO]

Am I the only one looking at the photos thinking that just two circuits for a 2 storey house in a mooban (a show house no less) seems a little strange?

[Crossy]

Am I the only one looking at the photos thinking that just two circuits for a 2 storey house in a mooban (a show house no less) seems a little strange?

Two 32A circuits no less, no you're not the only one but our OP is talking about a rewire in the near future.

[laislica]

We have two houses by the same builder.

They ate both wired the same!

As my wife says, in Thailand, the workers don't care about safety.

Strangely, I can only remember the tripping problem after dark.

The ceiling space with occasional scurrying has no access to the house or outside vents so I have no ides how anything could get in.

But an animal of some sort does fit the bill.

We leave in a couple of weeks so maybe I just change the main breaker for the 50A and get a proper job done next year.

The problem with a rewire is that the wiring was done, then wallpaper was added.

To rewire totally would be a very disruptive and expensive nightmare.

The mains enter the house just under the roof so it might be possible to trace where the aircon(s) are connected and re-route them to a proper distribution board with t cut installed.

Not a job I can do any more, eyes not good enough in dim lighting and not agile enough to be climbing about in roof spaces

We need to find a reliable electrician who knows what he is doing and will do a proper job without cutting corners - easy eh? LOL

Thanks for all the advice.

[lopburi3]

One thing that may not trip RCD is short from L to N as from a rat eating insulation on the wire - have had that happen myself. Rewire and upgrade entry box seems to be a priority.

[lj cm]

Good idea to rewire the whole house. Just be sure you are there to "supervise" the electricians.

We did it two years ago in our 15 year old house. The original wiring was a complete mess. It looked like a spider web.

And this is a "Land and House" project!.

[laislica]

Yes, whilst it would be more convenient to have the job done while we were away, there is every chance that they would replace one rats nest with another!

[LindaLovelace]

We have two houses by the same builder.

They ate both wired the same!

As my wife says, in Thailand, the workers don't care about safety.

Strangely, I can only remember the tripping problem after dark.

The ceiling space with occasional scurrying has no access to the house or outside vents so I have no ides how anything could get in.

But an animal of some sort does fit the bill.

We leave in a couple of weeks so maybe I just change the main breaker for the 50A and get a proper job done next year.

The problem with a rewire is that the wiring was done, then wallpaper was added.

To rewire totally would be a very disruptive and expensive nightmare.

The mains enter the house just under the roof so it might be possible to trace where the aircon(s) are connected and re-route them to a proper distribution board with t cut installed.

Not a job I can do any more, eyes not good enough in dim lighting and not agile enough to be climbing about in roof spaces

We need to find a reliable electrician who knows what he is doing and will do a proper job without cutting corners - easy eh? LOL

Thanks for all the advice.

I know this can't help the OP, but it might help somebody else.

I was going to add that his is exactly why folks planning to build a house should educate themselves and do it themselves so it's done right and they know it's done right. However, I understand there are people like the OP who simply cannot do this sort of thing anymore.

Some Thai electricians can wire a 3-way switch. I have never heard of a Thai electrician that ever even heard of a 4-way switch. Few use wire nuts. Polarity is typically given no consideration whatsoever. Grounds are often sloppy, not connected, or non-existent. And even where grounds are wired correctly in the house, they are often not properly connected to the rod, or the panel to rod wire is too small.

In my opinion, anyone planning to build a house would have money well spent on a [retired?] farang electrician consultant to ride herd on the Thai electricians. And by "ride herd," I mean watch every move and insist that things are done a certain way. It would improve safety, quality of life and a lot of future grief. Such a consultant can also make suggestions for the future that a Thai would never consider, such as a wire in a conduit for future outdoor lighting, etc.

Of course you could only hire a Thai that agreed to this arrangement before hand. Otherwise, most would simply walk off the job and never look back.

[LindaLovelace]

Yes, whilst it would be more convenient to have the job done while we were away, there is every chance that they would replace one rats nest with another!

Whoa!!!! While yo are away???? NEVER do that. Rule number one: Always be there.

One of my favorite TV ironies, if my memory serves me, was the need for Crossy to be back in the UK while his home was being wired, and when he returned . . . maybe he can tell the story.

[laislica]

Yes, whilst it would be more convenient to have the job done while we were away, there is every chance that they would replace one rats nest with another!

Whoa!!!! While yo are away???? NEVER do that. Rule number one: Always be there.

One of my favorite TV ironies, if my memory serves me, was the need for Crossy to be back in the UK while his home was being wired, and when he returned . . . maybe he can tell the story.

Do not worry, have another read at the post LOL