RCBO installed - issues

[topt]

After some recent threads I finally got around to having a Safe-T-Cut installed last week.

 

Some observations - 

Neither of the 2 Home Pro stores in Pattaya or Thai Watsadu appear to sell a Safe T Cut for 3 phases. Neither had anybody on several different visits who could give me any useful information and neither Home Pro store were able to advise an electrician/fitter - can only do for water heaters and a couple of other things.

Their 2 pole 50Amp Safe- T-Cut RCBO was over 5k baht.

 

Local electrical shop Pornchai on Pattaya Nua sold the model in the link below for 4,000 baht and when asked I was given contact details for 2 electricians. The lady owner in the left hand side (retail) shop speaks quite good English.

http://safe-t-cut.com/en/products/specail-a-3phese.html

 

Please see installed pictures below.

 

 

Issues -

Last night tried to use the extractor fan. Pressing any fan button or the light and the RCBO immediately tripped. There did not appear to be an issue with any other connections as everything had been working normally for a couple of days.

This morning the gf was using the hairdryer for quite a while and then seemingly for no other reason it tripped again.

 

The electrician has suggested that the tripping this morning is because of the heavy rain we had/dampness in the air .................but I do not really understand the explanation as neither his or my gf's English was up to the necessary detail.

 

Anybody have any suggestions particularly regarding the extractor?

Any obvious problems with the installation?

 

PS - the cream box top left contains all the TV co ax wires/connections - when the house was built they put a lot of sockets in all over the house. 

All sockets are 3 pin.

[bankruatsteve]

Does the RCBO have adjustable trip current settings?  Like, if it is set to 5ma, try the next higher setting.

 

Humidity can set them off - especially if the unit has dust webs or the like.  The extractor fan might have a gecko or ants laying eggs and creating a fault when power is applied.  (?)

 

Just some things to look for.  When you have an RCD in front of 3 phases the nuisance trips can be frustrating.  

[Crossy]

That it doesn't trip most of the time suggests it's wired correctly.

 

What mA range have you got it set to? Try the highest, usually 30mA.

 

It's possible the fan is faulty, or wired incorrectly (N to E). Check the fan wiring is correct, replace the fan with a lamp (disconnect the fan) and see if the problem goes away.

 

 

[Crossy]

Just now, bankruatsteve said:

When you have an RCD in front of 3 phases the nuisance trips can be frustrating.  

But are much less inconvenient than being dead.

[bankruatsteve]

12 minutes ago, Crossy said:

But are much less inconvenient than being dead.

Is "being dead" an oxymoron?  Point made in any case.

[Rally123]

Check to make sure your Negative/Neutral is not connected to your Earth. If it doesn't solve your probs go along to your Electric Company office and ask if they can send a reliable electrician to your house to check it out. They are Uni trained. They sorted out my similar problem and I wasn't charged.

[topt]

 

Quote

Humidity can set them off

So I guess that is what he was referring to 

Thanks

 

10 minutes ago, Crossy said:

What mA range have you got it set to? Try the highest, usually 30mA.

I and he tried that - still trips

 

11 minutes ago, Crossy said:

It's possible the fan is faulty, or wired incorrectly (N to E). Check the fan wiring is correct, replace the fan with a lamp (disconnect the fan) and see if the problem goes away.

That was my thought (that it must be wrong in some way as everything else seemed ok) and I will get him to check that - unfortunately I am going away so will have to wait.

[SomchaiDIY]

My idea can save much head pain with this problem

Go to electric supply store and ask for good electrician with insulation test equipments - many who work in commercial work have this

 

We use this test at our hotel resort locations and is best fast way to find leakage problem in circuits

 

Good idea you have all circuits checked with correct test or leakage breaker will make you crazy

 

If you have Thai translate problem put - insulation tester thailand - in google and show result in thai language 

[wgdanson]

1 hour ago, Rally123 said:

Check to make sure your Negative/Neutral is not connected to your Earth

My neutral is conneceted to Earth in the fuse cabinet. Is this dangerous or not please?

[jenny2017]

1 hour ago, Rally123 said:

Check to make sure your Negative/Neutral is not connected to your Earth. If it doesn't solve your probs go along to your Electric Company office and ask if they can send a reliable electrician to your house to check it out. They are Uni trained. They sorted out my similar problem and I wasn't charged.

Uni trained? I beg your pardon. Our son studied three years electronics at the local technical college and couldn't even replace a light bulb. 

 

  It's hard to find a good electrician who knows what he's doing. 

[stud858]

10 minutes ago, wgdanson said:

My neutral is conneceted to Earth in the fuse cabinet. Is this dangerous or not please?

Can you confirm where the "Earth" line you mention goes to.  Is it really an earth that travels down a thick cable to actual planet earth?

 

If it is, that's the reason of tripping.

Neutral should not be connected to earth.

[Crossy]

10 minutes ago, wgdanson said:

My neutral is conneceted to Earth in the fuse cabinet. Is this dangerous or not please?

It is correct assuming it's connected before your incoming breaker.

 

[bankruatsteve]

10 minutes ago, wgdanson said:

My neutral is conneceted to Earth in the fuse cabinet. Is this dangerous or not please?

Not.  That's correct for a "MEN" installation. 

[jenny2017]

12 minutes ago, wgdanson said:

My neutral is conneceted to Earth in the fuse cabinet. Is this dangerous or not please?

Here's a great explanation:

 

   https://scottiestech.info/2009/05/16/the-difference-between-neutral-and-earth-ground-in-ac-installations/

 

  Crossy, would you please have a look if that's right? Thank you very much!!! 

[wgdanson]

5 minutes ago, stud858 said:

Neutral should not be connected to earth.

 

3 minutes ago, Crossy said:

It is correct assuming it's connected before your incoming breaker.

 

Which one please? Neutral can be connected to my earth, which IS a bloody great cable going into the ground, if it is before the main breaker, yes?

 

[Crossy]

1 minute ago, Arjen said:

When this should be tje case it is even impossible to close the RCB(O)

OK. IMPORTANT NOTE.

 

Thailand is 3-phase 4-wire TNC-S with MEN. Have a look on Wikipedia for earthing systems.

N and E ARE connected at the transformer, and in your distribution board before the main breaker. The neutral is also grounded at every 3rd power pole.

 

If you have a N-E connection AFTER your RCBO it won't stay on or will trip randomly.

[Crossy]

2 minutes ago, wgdanson said:

Which one please? Neutral can be connected to my earth, which IS a bloody great cable going into the ground, if it is before the main breaker, yes?

As you have it is correct.

[wgdanson]

1 minute ago, Crossy said:

As you have it is correct.

Cheers Crossy, thanks.

[bankruatsteve]

1 minute ago, Crossy said:

If you have a N-E connection AFTER your RCBO it won't stay on or will trip randomly.

I think there also needs to be a load for that case.  (?)  IE: if no load then there couldn't be a N-E fault.

[Crossy]

Just now, bankruatsteve said:

I think there also needs to be a load for that case.  (?)  IE: if no load then there couldn't be a N-E fault.

Yeah, with no load the RCBO will likely stay on, but a load anywhere (not necessarily on that circuit) may get the N-E potential high enough to get >30mA flowing, trip time ?

 

[stud858]

4 minutes ago, wgdanson said:

 

 

Which one please? Neutral can be connected to my earth, which IS a bloody great cable going into the ground, if it is before the main breaker, yes?

 

My concern was for having neutral joined to earth after the breaker which wouldnt allow all the inflow current to match the flow back through the neutral. Some would divert away from the breaker and go through ground earth,  hence tripping the breaker every time.

You should get someone to check with a multimeter if neutral is joined to earth after the breaker.

Otherwise, other advice regarding swapping over loads and cleaning is good.

[bankruatsteve]

2 minutes ago, stud858 said:

My concern was for having neutral joined to earth after the breaker which wouldnt allow all the inflow current to match the flow back through the neutral. Some would divert away from the breaker and go through ground earth,  hence tripping the breaker every time.

You should get someone to check with a multimeter if neutral is joined to earth after the breaker.

Otherwise, other advice regarding swapping over loads and cleaning is good.

Ya.  Except joining N-E somewhere in the circuit is not a normal practice, even in Thailand.  Like L-E faults, a N-E fault is usually critter or dust related.

[Crossy]

5 minutes ago, bankruatsteve said:

Except joining N-E somewhere in the circuit is not a normal practice, even in Thailand.

Wanna bet? One of our sparkies connected N-E in the back of the outlets even though there was a ground wire. At least it meant I took off all the outlets and put them the right way up (and fixed a couple that were reverse polarity.

[bankruatsteve]

2 minutes ago, Crossy said:

Wanna bet? One of our sparkies connected N-E in the back of the outlets even though there was a ground wire. At least it meant I took off all the outlets and put them the right way up (and fixed a couple that were reverse polarity.

Oh dear.  Can I get credit for saying it's not "normal" practice.  

[upu2]

is your incoming supply actually a 3 phase supply? It just looks like the normal L, N and E

 

Three phase would normally be 4 wires i.e. Ph1, Ph2, Ph3 and Earth

[stud858]

18 minutes ago, upu2 said:

is your incoming supply actually a 3 phase supply? It just looks like the normal L, N and E

 

Three phase would normally be 4 wires i.e. Ph1, Ph2, Ph3 and Earth

I saw 4 wires enter at top in his picture . 3 phase I reckon.

[bankruatsteve]

20 minutes ago, upu2 said:

is your incoming supply actually a 3 phase supply? It just looks like the normal L, N and E

 

Three phase would normally be 4 wires i.e. Ph1, Ph2, Ph3 and Earth

That would be neutral (not earth) that isn't going through the breaker.

[wgdanson]

43 minutes ago, upu2 said:

is your incoming supply actually a 3 phase supply? It just looks like the normal L, N and E

 

Three phase would normally be 4 wires i.e. Ph1, Ph2, Ph3 and Earth

My supply is two cables coming from the pole outside. There is a L & N (black & white) cable coming into the fuse box, and a big green one going into the ground.

[topt]

1 hour ago, upu2 said:

is your incoming supply actually a 3 phase supply? It just looks like the normal L, N and E

 

Three phase would normally be 4 wires i.e. Ph1, Ph2, Ph3 and Earth

Your eye sight must be worse then mine 

Definitely 3 phase.

 

Based on (so far) no negative feedback on the picture and what I saw happening I think the electrician knew what he was doing. Before installing he did advise that he would not be responsible if some of the house wiring caused the RCBO to trip and he had to search for a solution............

[Rally123]

3 hours ago, wgdanson said:

My neutral is conneceted to Earth in the fuse cabinet. Is this dangerous or not please?

It was in my consumer unit also. Resulting in us receiving a mild electric shock when using the shower/heater. The RCB also tripped occasionally as I recall. After the Neutral was disconnected to the Earth the shocks stopped and the RCB also stopped tripping.