RCBO tripping why?

[Swiss1960]

As title says,  my RCBO starts tripping, sometimes not for hours, sometimes every few mins, mostly when it is damn hot. Doesn't matter whether it is on 5mA, 15mA, 25mA or direct.

 

Worked flawless for weeks, no new devices added, no cable works done, never worried what was running concurrently. Washing machine,  pool pump,  TV, fridge, poll robot, small oven, 2 fans,  treadmill all behind the safety.

 

So far, did not see any pattern for tripping. Could it be the heat?

[bankruatsteve]

That appears to be RCD only (not RCBO).  Don't know why it is labelled "Current Coil".  (?)

Anyway...

We had a thread a while back where it turned out the unit got a bit fried because of loose connection making it defective.  Maybe check for that?  

The "Test" button also causes trip, right?

[Crossy]

If it's opening on "Direct" (RCD function disabled) and it's not an RCBO (opening on over-current) then it's busted.

 

Time for a new unit methinks.

 

[bankruatsteve]

Didn't notice before, but looks like 50 is stamped next to A.  So, whose know.

[lopburi3]

1 hour ago, Swiss1960 said:

Washing machine,  pool pump,  TV, fridge, poll robot, small oven, 2 fans,  treadmill all behind the safety.

Those wires appear very small, especially at top for anything drawing much current (but perhaps just my eyesight). As said could well be defective unit but really would look into larger/more wires as ovens can pull a lot of current although if really rated 50 amps seems strange - have you noticed how hot the wires are getting (be careful to to touch anything bare).  

[Metropolitian]

7 hours ago, Swiss1960 said:

Worked flawless for weeks, no new devices added, no cable works done, never worried what was running concurrently. Washing machine,  pool pump,  TV, fridge, poll robot, small oven, 2 fans,  treadmill all behind the safety.

No consumer unit ? 

If so, also check the washing machine,  pool pump, fridge, small oven, and treadmill.

 

There was a setup at parents-in-laws with only a knife switch and one main breaker (50A) which tripped. (the knife switch fuse only got hot before the main breaker tripped)

After deductions the culprit was found and finger pointing to the old fridge. Disconnected and everything was okaydokey after.

Wiring was all 1.5mm

 

 

[Metropolitian]

5 hours ago, lopburi3 said:

Those wires appear very small, especially at top

Right, and the top should be the main input. Wondering were the real mains is perhaps the OP can tell us more about his situation.

Top wiring looks like they are 1.5mm and the out wiring 2.5mm (colored conform European standards brown and blue, so installed by foreigner probably)

[Crossy]

If it is a 50A RCBO and is tripping on "Direct" then it's the over-current trip that's opening.

 

The fact that it's doing it when it's very hot suggests that the thermal section of the trip may be the culprit. Once again it's time for as new unit.

 

I'm assuming that our OP isn't pulling 50A or anything like (wires look a bit puny for that)

[Swiss1960]

Sorry guys for the late reply. Thanks for your contributions so far and here my answers:

• Yes, next to "CURRENT" it has 50 engraved. 
• Using the "TEST" button, it trips on 5, 15 and 25mA but not on "DIRECT" (guess that is normal?)
• Cables you seen on top are coming from the house to the RCBO, are there since ages. They have their own fuse in the kitchen, see attached pic, right-most fuse is for outside and only outside. 
• Cable from the RCBO to the first plug was 2x1.5, but that burnt through some weeks ago (burnt exactly where they come out of the RCBO) and I had them replaced with 2x2.5, that is what you now see coming out in red and brown
• Still have to check whether it will trip when on "DIRECT", but now everything runs stable
• Heat I have to check next time it trips, so far this morning (cool morning with only around 33 degrees), no heat at all. SOME cables run in their tubes behind the oven and probably pretty hot when I am baking, could that cause the tripping? 

Finally, if I have to replace, what kind of would you suggest and where to buy?

[lopburi3]

If trips your 50 amp breaker on direct (which OP says) but not your 16 amp breaker upstream it must need replacement (but strongly advise replacing those wires from breaker panel at same time as they are too small).  Safe-t-cut is the original Thai company making such units (from 1978 or so) and I would go with them even if a bit more expensive (mine from 1978 still working fine).  If all working OK now avoid using direct (no protection) but as said get that wire from main panel replaced with at least 2.5mm.  Do you have any ground for other wires?  That is also worthwhile having.

[Metropolitian]

4 hours ago, Crossy said:

The fact that it's doing it when it's very hot suggests that the thermal section of the trip may be the culprit

Not arguing on that.  It's very reasonable to say that the breaker is failing, it looks aged.

 

Another fact is that fridges are working harder and more when it's very hot. ????

And a compressor nearing it's lifespan and failing has a very high current usage.

 

Still want to know if there are more breakers, especially behind the RCBO, if yes, then it's 100% the RCBO failing.

Unless we get the whole picture we only could guess, yours is a good one.

 

[Metropolitian]

29 minutes ago, Swiss1960 said:

Sorry guys for the late reply. Thanks for your contributions so far and here my answers:

• Yes, next to "CURRENT" it has 50 engraved. 
• Using the "TEST" button, it trips on 5, 15 and 25mA but not on "DIRECT" (guess that is normal?)

Yes.

 

29 minutes ago, Swiss1960 said:

• Cables you seen on top are coming from the house to the RCBO, are there since ages. They have their own fuse in the kitchen, see attached pic, right-most fuse is for outside and only outside. 

[pool-washing-patio]

And that is connected to the RCBO before going outside?

 

And did you say that ' Washing machine,  pool pump,  TV, fridge, poll robot, small oven, 2 fans,  treadmill' are behind it? Sure?

Do check the grouping (by turning off the right-most 'fuse' (breaker) and turning on the fans, oven, tv,..

 

It's either protecting the outside are and not the tv fridge oven and fans or all these devices are outside on the patio.

 

 

 

29 minutes ago, Swiss1960 said:

• Cable from the RCBO to the first plug was 2x1.5, but that burnt through some weeks ago (burnt exactly where they come out of the RCBO) and I had them replaced with 2x2.5, that is what you now see coming out in red and brown
• Still have to check whether it will trip when on "DIRECT", but now everything runs stable

 

Ohh.. so it's not sure that it would be an overcurrent issue but possibly an earth leaking issue.

 

Please to tell if NO trip occurs while in the 'DIRECT' position. 

As this then means there's an earth leak failure somewhere which can be dangerous, and you're then not protected with the dial in 'direct'.

 

 

29 minutes ago, Swiss1960 said:

• Heat I have to check next time it trips, so far this morning (cool morning with only around 33 degrees), no heat at all. SOME cables run in their tubes behind the oven and probably pretty hot when I am baking, could that cause the tripping? 

Finally, if I have to replace, what kind of would you suggest and where to buy?

 

[Swiss1960]

Sorry again for late reply, tried to find out more about why it trips and why not... but can not find a culprit like i.e. pool-pump starting or using oven.. now for few days - yes, some rain and lower outside temps - no trips at all, so clearly seems to be the RCBO problem itself.

 

@lopburi3 Yes, the current RCBO is getting quite a bit hot when too many things are in use at any one time, so that might well be the issue. Where would I find a replacement for my RCBO? I don't want to buy some fake Chinese product over Lazada

 

@Metropolitian Sorry that I was unclear before. All the devices I mentioned are in the pool area behind the RCBO. So the flow is from the kitchen fuse panel to the RCBO to the washing machine, the pool pump and all those devices in the Patio area (my patio is MY kingdom, so everything is there I need..). For your question about earthing, I think the fuse box in the kitchen has proper earthing, I remember @Crossy confirmed in another thread that it looks like the earthing-wires are there at least. 

 

So i guess to be on the safe side, replacement it is, question is from where and how much, what would you specialists recommend?

[Crossy]

4 hours ago, Swiss1960 said:

So i guess to be on the safe side, replacement it is, question is from where and how much, what would you specialists recommend?

 

Since it's already on a sub-circuit you don't need anything flash. 

 

Haco and others do some neat little RCBO's 

https://www.hacothailand.com/product/earth-leakage-breaker-2p-1e-with-blue-lamp/ 

All the big DIY places have them, 450 Baht or so with a neat little plastic box.

 

NOTE:- Unlike many RCD/RCBOs these must be connected the right way round, you can't swap the Line and Load terminals. They still work, until you push the Test button then the magic smoke comes out. Ask me how I know

 

[Crossy]

OR

 

You could replace the breaker in your consumer unit and do away with the external box altogether, 1,170 Baht.

 

https://www.homepro.co.th/p/1023274

 

[BritManToo]

Complete unit with 8 fuses ...... 800bht.

https://shopee.co.th/ตู้ไฟกันดูด-ตู้โหลดNANO-แท้100-ตู้กันดูด-ขนาด-6-ช่อง-63A-RCBO-(สีขาว)-พร้อมส่งทันทีครับ-i.6357509.6133432962

[Swiss1960]

Thanks @Crossy

Just been made aware that the magnetic circuit breaker in my pool panel has problems, horrible sound like a bee hive, when the pump starts, takes almost 15 seconds. Sound goes away when I press the black square in the middle. Could this cause the issues with the breaker? So far, it does not seem to be connected, but what do I know

[Crossy]

3 minutes ago, Swiss1960 said:

Could this cause the issues with the breaker? So far, it does not seem to be connected, but what do I know

 

Probably not, but a buzzing contactor can be a sign of low supply voltage.

[Crossy]

2 hours ago, BritManToo said:

Complete unit with 8 fuses ...... 800bht.

https://shopee.co.th/ตู้ไฟกันดูด-ตู้โหลดNANO-แท้100-ตู้กันดูด-ขนาด-6-ช่อง-63A-RCBO-(สีขาว)-พร้อมส่งทันทีครับ-i.6357509.6133432962

 

That's pretty cheap, I wonder what the build quality is like.

 

It even has sensible ratings for the MCBs.

[BritManToo]

Just now, Crossy said:

That's pretty cheap, I wonder what the build quality is like.

It even has sensible ratings for the MCBs.

The individual fuses (35bht each) seem as solid and reliable as any other make I've tried.

[lopburi3]

It really is amazing how cheap some items are these days - just bought below 99 baht scale to replace a 200 baht model that worked great for several years (until someone dropped water cooler jug full of water on it from about 1.5 meter high).  

https://shopee.co.th/product/158271599/5932271274

[Swiss1960]

16 minutes ago, Crossy said:

 

Probably not, but a buzzing contactor can be a sign of low supply voltage.

Phase protector does not show supply problems and when I press the square in the middle of the breaker, the sound goes away

[Crossy]

5 minutes ago, Swiss1960 said:

Phase protector does not show supply problems and when I press the square in the middle of the breaker, the sound goes away

 

We have one that makes a godawful racket even at 205V which should be well within its operating range.

 

Check the actual voltage at the coil connections of the contactor, could be a high resistance contact somewhere.

 

Failing that, time for a new contactor ????

 

 

 

 

[Metropolitian]

1 hour ago, Crossy said:

 

That's pretty cheap, I wonder what the build quality is like.

 

It even has sensible ratings for the MCBs.

Have them here too.

Pretty good quality but a few design flaws.

Pros

• Metal casing (plastic cover)
• Made in thailand, so the prices are kept low (no imports)
• MCB comes with their own colored levers. (easier telling missus pulling down that one mcb)
• You can pop out a square hole just flat at the back plate. Happy trunking.

Cons

• Bus bar is too short, with my 11-slots CU only has a busbar with 6 points.
• Tightening the terminal screws too much the breaker splits easy (but not breaks)
• The Led light is not a led but neon
• It came with too less stickers (as opposed in the sales pictures)

The bus bar 'problem' I solved with using another bus bar, stickers from another CU and who doesn't love neon ????

 

[Metropolitian]

1 hour ago, BritManToo said:

The individual fuses (35bht each) seem as solid and reliable as any other make I've tried.

Agree. (even on the 'seem' aspect) They haven't failed me till now.

  

 

 

 

[Blue Muton]

When I see threads like these I've come to think they should be titled "Dear Crossy...."

[Metropolitian]

5 hours ago, Crossy said:

.. you can't swap the Line and Load terminals. They still work, until you push the Test button then the magic smoke comes out.
Ask me how I know

 

          How  ?    ????

 

 

 

BTW. It's the same as with the RCBO from the Nano products line. A sticker put on the terminal warning you which one is the lead and the load. 

We have to hope never have someone trying to push the test button just in the few seconds after the grid went off (..and the solar still feeding)

[Metropolitian]

10 hours ago, Swiss1960 said:

All the devices I mentioned are in the pool area behind the RCBO. So the flow is from the kitchen fuse panel to the RCBO to ..

Plus

Quote

Yes, the current RCBO is getting quite a bit hot when too many things are in use at any one time,

A great indication the RCBO has to be replaced.

It was rated as 50A and getting hot with a load not even exceeding 16A while sitting behind the kitchen fuse/mcb which is rated 16A is a signal 'replace me'.

 

 

 

10 hours ago, Swiss1960 said:

     Metropolitian: " would be an overcurrent issue but possibly an earth leaking issue. "

 

For your question about earthing, I think the fuse box in the kitchen has proper earthing, I remember @Crossy confirmed in another thread that it looks like the earthing-wires are there at least. 

Some misunderstanding I think. What I meant with 'Earth leaking issue' is a connection between the live and the earth wire which you need to have for the RCBO to trip.

They sense imbalance as the current doesn't flow back from live to neutral but pass the earth and bypassing the RCBO T-core, that's I called 'Earth Leak Issue'.

 

[Metropolitian]

17 minutes ago, Blue Muton said:

When I see threads like these I've come to think they should be titled "Dear Crossy...."

Thanks. Now I remember the page in Seventeens starting with 'Dear Mona...' ????

 

[lopburi3]

3 minutes ago, Metropolitian said:

What I meant with 'Earth leaking issue' is a connection between the live and the earth wire which you need to have for the RCBO to trip.

They sense imbalance as the current doesn't flow back from live to neutral but pass the earth and bypassing the RCBO T-core, that's I called 'Earth Leak Issue'.

But you do not need any earth wire for a difference to be detected between L and N.  RCBO will operate fine without ground wire and is a prime reason to have here where many homes do not have proper earth ground and you become the potential ground path (but of course best to have both).