Jump to content
BANGKOK
Susco

Another RCBO tripping

Recommended Posts

I enable breaker from aircon, it is open by default because I never use aircon in that room, open the aircon and after about 10 minutes the RCBO trips.

 

Since then I just enable the breaker, without the aircon running, and after 15 seconds RCBO trips each time.

 

Where should I start looking?

Share this post


Link to post
Share on other sites

Is it a plain breaker or a RCBO.

 

Many breakers for the aircons here in Thailand do look like those :

39656.jpg.d44c3d8cb6628d12a784d895c2096e64.jpg

 

And RCBO's come in many forms and sizes, they share one specific thing and that's having an -TEST- button.

7e608e6bb0f126f0bab7e0efba1e0016_tn.jpg.407998bb97a4efdc23e7a401e7850029.jpg

Share this post


Link to post
Share on other sites

Personally I'd suspect a bad breaker and suggest you disconnect the load wire and see if it still trips.

Share this post


Link to post
Share on other sites
9 minutes ago, RichCor said:

Personally I'd suspect a bad breaker and suggest you disconnect the load wire and see if it still trips.

If I disconnect the load wire from the breaker the rcbo obviously can not trip any more, or do I miss something?

 

But how would that determine if the breaker is bad or not?

Share this post


Link to post
Share on other sites

 

1 hour ago, Susco said:

I enable breaker from aircon, it is open by default because I never use aircon in that room, open the aircon and after about 10 minutes the RCBO trips.

 

Since then I just enable the breaker, without the aircon running, and after 15 seconds RCBO trips each time.

 

Where should I start looking?

 

 

I can read this in two ways:

 

Breaker for the aircon on the wall turned on (enabled) and it turned on the aircon for 10 minutes and then the RCBO in the consumer unit tripped.

And after that, without operating the aircon, by turning the breaker for the aircon on the RCBO in the consumer unit tripped.

   ->  The breaker has probably failed, it worked for ten minutes and then something inside the breaker went bad and consequentially tripping the RCBO in the consumer unit.

   = replace the breaker (but do read the footnote * )

 

The breaker on the wall, and assumed as an RCBO which it probably isn't (but not impossible because RCBO themself CAN be used as an 'breaker-on-the-wall' for aircons), trips after ten minutes of operating of the aircon and afterwards failing after 15 seconds then the story is the same as above = replace the breaker/rcbo.

 

* There is another possibility and that's when the problem is in the feed from the breaker to the aircon or at the aircon itself.

To eliminate that probability you could disconnect the wire going to the aircon at the breaker.

If problem persist, it is the breaker.

If there's no tripping, do check the wiring and the terminals at the aircon.

 

Share this post


Link to post
Share on other sites

There is no breaker on the wall, we are talking here about a proper consumer unit with ABB MCB's and a RCBO

  • Like 1

Share this post


Link to post
Share on other sites
5 minutes ago, Metropolitian said:

The breaker on the wall, and assumed as an RCBO which it probably isn't (but not impossible because RCBO themself CAN be used as an 'breaker-on-the-wall' for aircons)

A stand-alone RCBO on the wall isn’t at all difficult to imagine. They look very similar to the switches at the top in your first picture and are around 350 baht depending on the rating. The test button is the only giveaway from a distance. I use one as an on/off switch on my homemade polishing wheel and wire brush, it’s probably unnecessary but the difference in cost is minimal.

Share this post


Link to post
Share on other sites
8 minutes ago, Susco said:

There is no breaker on the wall, we are talking here about a proper consumer unit with ABB MCB's and a RCBO

 

(MAKE SURE THE ELECTRIC IS OFF AND DO SO EACH NUMBERED STEP)

 

1. check the wiring and connection at the terminal in the aircon

 

test..

 

If trips, then

 

2. disconnect the wiring in the aircon and tape off the ends.  (to eliminate the problem being inside the aircon or outdoor unit itself)

 

test..

 

If trips, then

 

3. Check the wiring/connection and the rcbo in the consumer unit (discoloration of the rcbo/loose screws/burn marks/molten insulation at the terminals)

 

Looks good?

 

4. Disconnect the wiring from the RCBO, that goes to the aircon, in the consumer unit (to eliminate the problem in the wiring from CU to the AC)

 

test..

 

If trips, then

 

5. Replace the RCBO.

 

 

  • Like 1

Share this post


Link to post
Share on other sites

If we are talking about two separate breakers in the consumer unit, the one being the RCBO and the other the breaker then..

 

 

 

3. Check the wiring/connection and the breaker in the consumer unit (discoloration of the breaker/loose screws/burn marks/molten insulation at the terminals)

 

Looks good?

 

4. Disconnect the wiring from the breaker, that goes to the aircon, in the consumer unit (to eliminate the problem in the wiring from CU to the AC)

 

test..

 

If trips, then if behind the RCBO are more breakers and the RCBO works fine with them, then..

 

5. Replace the breaker.

Share this post


Link to post
Share on other sites
2 hours ago, Susco said:

Where should I start looking?

It would be good for us to help you if you provided us with a photo of the actual consumer unit (front and later we can ask for the inside if you are able to handle that) and the aircon.

Share this post


Link to post
Share on other sites
29 minutes ago, Susco said:

If I disconnect the load wire from the breaker the rcbo obviously can not trip any more, or do I miss something?

 

But how would that determine if the breaker is bad or not?

 

The 'trip' could be indicative of an actual fault, a failing breaker, or a nuisance (indeterminate) borderline fault.

 

Without proper test gear we are forced to resort to simplified order elimination or replacement and hope when the issue stops being an issue we've solved it (and not buried the fault to later bite us in the a$$).

 

Metropolitian seems to have you covered for the moment.

  • Like 2

Share this post


Link to post
Share on other sites
Posted (edited)
11 minutes ago, Metropolitian said:

If trips, then

 

5. Replace the RCBO.

There is no wiring that goes from the RCBO to the aircon, wiring goes from the MCB to the aircon. There are 12 MCB's behind that specific RCBO..

 

I have to say that occasionally the  RCBO has tripped spontaneously in the past, without the aircon breaker engaged, but then I just switch on again and it may trip again in a month or two

 

Edit to correct without

Edited by Susco

Share this post


Link to post
Share on other sites
3 minutes ago, Susco said:

There is no wiring that goes from the RCBO to the aircon, wiring goes from the MCB to the aircon. There are 12 MCB's behind that specific RCBO..

 

I have to say that occasionally the  RCBO has tripped spontaneously in the past, without the aircon breaker engaged, but then I just switch on again and it may trip again in a month or two

 

Edit to correct without

Check post #9 😉  a follow up of the steps mentioned in post #8 but #9 is now the right list for you.


It -can- be the faulty breaker (MCB) that cause the RCBO trip.

 

As you said there's 12 MCB's behind that one RCBO and in normal use it only trips once in a month or two then for now we should look at the MCB for the aircon or the wiring to the aircon.

So again check the steps in post #9 to eliminate the fault from end to begin.

  • Like 1

Share this post


Link to post
Share on other sites

Last time this came up recently it was a loose wire connection on the back of the rcbo if I remember correctly. Days of speculation before pulling the breaker and seeing the back scorched a little. 
You can see the thread in the electrical forum. 

Share this post


Link to post
Share on other sites
14 minutes ago, Metropolitian said:

4. Disconnect the wiring from the breaker, that goes to the aircon, in the consumer unit (to eliminate the problem in the wiring from CU to the AC)

 

 

I don't have the consumer unit open right now, but if I remember correctly, all breaker at the bottom are interconnected by a bus bar, and at the top are all the red wires.

 

The red wire is the one that I have to disconnect, right?

 

 

  • Like 2

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...