Udon Thani dentist

[tlcwaterfall]

Need some help please.

 

Our safety switch is switching off the power every day between 11am and midday. When we try to push the switch up to the correct position it will not go up.

I have tried the different sensitivity positions but it still goes off each day. After two to three hours we can then push the safety switch up to the correct position and power is restored and remains on until the next day and then goes off again between 11am and midday.

 

Can anyone please offer some suggestions as to why this is happening and a solution.

[yeahbutif]

Could be a wiring fault to make power trip .. the switch maybe not tripping fast enough so  overheating. And the switch getting week.    Get electrician to check.. 

[London Lowf]

A long shot - is the switch exposed to dirct sunlight and getting heated up as the day warms up? It shouldn't make that much difference but this is straw-clutching from afar.

[blackcab]

Do you have a device that is activated around about that time every day? Do you have a pump on a timer, or does a human always make a cup of tea or turn on a device at that particular time?

 

Perhaps you could work out exactly what is powered by that circuit and narrow down any possible devices by using a process of elimination?

[bluejets]

Get a lecky to disconnect and test the load with a megger.

"our safety switch" makes me think you have only the one, and any loads connected will "add up" the leakage of each circuit.

As others have commented, is there anything in particular that switches at that time.

(Even though being connected via the neutral is enought for a faulty device to cause a trip at any time.)

Perhaps someting gets "plugged in" at that time or perhaps just a co-incidence.

Not using electrically noisy devices at that time...?? welders etc.

[carlyai]

Also, as well as the above, have you pressed the 'test' button, then reset the switch 'on'. 

Just testing that the switch is not faulty. If the switch is difficult to reset, then it could be a faulty switch.

[Dazinoz]

It sounds as though a set up like mine that has one "safety switch" feeding all circuits through individual breakers.

 

I doubt it is a faulty switch as it happens same time everyday.

 

Suggest when it trips next time try once to reset. If it doesn't, switch all other breakers off and try reset. If it resets turn all breakers on one at a time allowing several seconds between turning each on. If it trips when a circuit is switched on. Then try and find what's on that circuit.

 

If that doesn't work, back to the drawing board.

[carlyai]

 

'I doubt it is a faulty switch as it happens same time everyday.'

But it won't reset until after a while. Yes the fault may still be there or switch trouble. Easy enough to check.

[Artisi]

tomorrow morning at just prior to 11 turn everything in the house OFF and see what happens. 

It could be something else local that is triggering the trip. 

I had a problem a few years back, every evening when the streetlights turned on the neutral incoming line increased to 25 / 30 volts, this fooled my RCBO and it wouldn't trip on test - come morning and the lights went off, everything back to normal.

 

[The Theory]

Is the RCBO old type or new ? 
If it is an old type and there is a selector with 3 levels, just wash it by "Electronic cleaner spray"(move the selectors to both ends while sprayed). If it's a newer type then you need to have some sense of electrical troubleshooting. For start as already mentioned turn of all breakers before the time. See what happens. 
but my guess is perhaps you need to replace it with a new one. It has become sensitive. 

Edited February 25, 2023 by The Theory

[The Theory]

If one of lines have problem that cause RCBO trip then you need to find that line, try one by one. How many breakers ? You need to test one by one.

Next day if RCBO trip and you can not turn it back on. Try to turn off breakers one by one and for each breaker you turn off test the RCBO, if it holds. 
and if you find a bad line, then you can find the possible bad user on that line. 
 

 

Edited February 25, 2023 by The Theory

[nauseus]

From what you say it will be heat-related.

 

Solution could be to replace the switch.

 

Any warranty?

[Crossy]

@tlcwaterfall can you post a decent photo of the breaker after it has tripped, there are indicators that tell you whether it went on over current or earth leakage.

 

The result will tell us which direction your investigation should go.

[carlyai]

6 minutes ago, Crossy said:

@tlcwaterfall can you post a decent photo of the breaker after it has tripped, there are indicators that tell you whether it went on over current or earth leakage.

 

The result will tell us which direction your investigation should go.

What are the indications?

[Crossy]

3 minutes ago, carlyai said:

What are the indications?

 

It depends upon the exact model (hence asking for the photo) but it's generally a mechanical indicator on the RCD section which shows when that section caused the trip.

 

Indicator shows = earth leakage issue, indicator does not show = overload issue.

 

[bluejets]

23 hours ago, carlyai said:

But it won't reset until after a while.

Sounds like overcurrent........but then, what is "after a while"?

[carlyai]

1 hour ago, bluejets said:

Sounds like overcurrent........but then, what is "after a while"?

OP said several hours.

[JBChiangRai]

Does one of your neighbours have grid-tied solar power?  If they have check the voltage at the time it trips, maybe it's too high in which case you would need the next breaker size up.

[tlcwaterfall]

5 hours ago, Crossy said:

@tlcwaterfall can you post a decent photo of the breaker after it has tripped, there are indicators that tell you whether it went on over current or earth leakage.

 

The result will tell us which direction your investigation should go.

Photos taken after power went off at 11.06am. I pushed the safety switch back up at 11.08am and now waiting to see what happens.

 

Edited February 26, 2023 by tlcwaterfall

[Crossy]

OK, typical you have a model without the indicator ???? 

 

Does the sensitivity switch move to the red area? Is that marked "off" or "bypass"? And if it does, does the unit still trip?

 

I'd certainly set the beast to 25mA, although you suggest it makes no difference.

[tlcwaterfall]

3 minutes ago, Crossy said:

OK, typical you have a model without the indicator ???? 

 

Does the sensitivity switch move to the red area? Is that marked "off" or "bypass"?

 

I'd certainly set the beast to 25mA, although you suggest it makes no difference.

Thank you for your help.

 

I can move the the switch to the red area and it it is marked as "Direct"

 

Power has remained on since 11.08am so that is a good thing.

[Crossy]

OK, does it trip in "direct" mode is the next question?

 

When it trips again, switch to Direct and report please.

 

Note that Direct actually disables the earth-leakage detection so you lose some safety.

 

The newer units don't have it so it's pretty old and may actually be dying, could be time for a new one anyway.

 

EDIT I also note that you have only 32A breakers, are there any cooking appliances / water heaters / big pumps that fire up at the same time each day? What size meter do you have (post a photo if you don't know). You may actually be exceeding the 32A rating.

 

[tlcwaterfall]

2 hours ago, Crossy said:

OK, does it trip in "direct" mode is the next question?

 

When it trips again, switch to Direct and report please.

 

Note that Direct actually disables the earth-leakage detection so you lose some safety.

 

The newer units don't have it so it's pretty old and may actually be dying, could be time for a new one anyway.

 

EDIT I also note that you have only 32A breakers, are there any cooking appliances / water heaters / big pumps that fire up at the same time each day? What size meter do you have (post a photo if you don't know). You may actually be exceeding the 32A rating.

 

Placed the safety switch to direct  and so far it has not tripped. No items are turned on at the same time each day.

 

An electrician checked out all the wiring and the safety switch and he has no idea what is triggering the safety switch.

[Crossy]

OK, you have a 15/45 meter which would normally have a 50A main breaker, if it does turn out to be overload then there's an upgrade route (subject to your incoming cable being suitable).

 

Leave it on Direct for a while, if it no longer trips out then we have an earth leak to locate, these can be "fun", not.

 

[bluejets]

If no one circuit at fault, then it has to be cumulative.

 

"An electrician checked out all the wiring and the safety switch" ....... without knowing exactly what they did, one cannot comment.

 

Edited February 27, 2023 by bluejets

[tlcwaterfall]

On 2/26/2023 at 2:35 PM, Crossy said:

OK, you have a 15/45 meter which would normally have a 50A main breaker, if it does turn out to be overload then there's an upgrade route (subject to your incoming cable being suitable).

 

Leave it on Direct for a while, if it no longer trips out then we have an earth leak to locate, these can be "fun", not.

 

Placed it on to Direct at 9am this morning and now as at 12.45pm power has remained on.

[Artisi]

8 minutes ago, tlcwaterfall said:

Placed it on to Direct at 9am this morning and now as at 12.45pm power has remained on.

Note to Crossy - any chance that something external is triggering the trip?  

[NotEinstein]

Could very easily beat a nearby house if the others around don't have earth leakage detect, or even an earth. In effect, yours becomes the only point that can react to a short circuit. I recently updated an old house's supply, fitting a breaker box and earth - when I connected the earth, which is tied to neutral, there was a spark, telling me the other houses are not earth tied to neutral.

[bluejets]

16 hours ago, NotEinstein said:

Could very easily beat a nearby house

Not likely on earth leakage as it requires the imbalance to be detected on the "load" side of the torroid.

 

[carlyai]

Not too sure where the OP is up to in their fault finding progression, but, to me, a few things don't add up, or maybe I missed something?

Firstly the fault seemed to come on about the same time and the breaker couldn't be reset for a few hours.

Then while testing the breaker could be reset, not having to wait. What changed?

Placing the unit in Direct mode stopped the unit from tripping, OK could be a leakage fault, but initially, if it is/was a leakage fault, it seemed to clear after a few hours and the breaker could be reset. Strange fault (Ahhhh, those red ants) as the leakage fault seems to clear.

So at the moment, the SafetyCut doesn't trip in the Direct switch connection.

Now the OP is looking for a leakage fault by isolating loads and turning off breakers. Is that correct.

I'd still replace that SafetyCut with a newer unit.