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kuzmabruk

Safe-T-Cut Tripping Too Often

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1 hour ago, fredob43 said:

I cant show the split but can show snap of the upgraded Meter.

 

OK, that is a 30/100 meter, somewhere between it and the rest of the installation should be a 100A breaker or HRC fuse.

 

Can you sketch out your internal distribution system. I am seriously worried about the size of your sub-main wiring. I wouldn't have any subs of less than 10mm2 with a 50A breaker protecting the supply end.

 

The problem is that, once you have a permanent supply (4 Baht per unit) you can pretty much do what you like until you melt the meter (300A+). Also, unlike the UK, there is no DNO fuse. Short your incoming supply and the only overcurrent protection is the X00A drop fuses that protect the transformer.

 

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14 hours ago, sometimewoodworker said:

Including the nice 220~230v 30A current flowing through you in the event that there is a fault. FWIW 0.02A to 0.03A for a short time is enough to kill you if flowing from hand to hand, you will also be unable to let go as the current will clamp your hands shut, and without the RCBO to cut the current to save you it can also kill anyone who tries to rescue you.

 

Luckily we don't have 110v as that is even more dangerous and without immediate access to a defibrillator is even more likely to kill you as it disrupts the heart rhythm and causes Ventricular fibrillation (harder to stop) rather than 230v which is more likely to stop the heart completely (easier to restart with chest compressions)

I had always considered the 110v system much safer than the 220v due to the centre tap transformer arrangement giving only 55v to Earth which is for sure the most likely scenario if you are going to come in contact a live wire.

 

 

Den

Edited by denby45

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4 hours ago, denby45 said:

I had always considered the 110v system much safer than the 220v due to the centre tap transformer arrangement giving only 55v to Earth which is for sure the most likely scenario if you are going to come in contact a live wire.

 

That's true for a 110V (55V-0-55V) centre-tap system such as a site-transformer you would find in the UK for 110V tools.

 

One of these:-

 

102174_xl.jpg

 

The US system is 120V-0-120V so contact is going to be 120V WRT ground, potentially a smaller shock current but still a nasty bite.

 

Incidentally usless fact - The first man to die from electrocution in the Royal Navy was killed by a 48V DC supply. He apparently became trapped on a bus-bar and fried slowly 😞

 

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6 hours ago, denby45 said:

I had always considered the 110v system much safer than the 220v due to the centre tap transformer arrangement giving only 55v to Earth which is for sure the most likely scenario if you are going to come in contact a live wire.

 

Den

As crossy has said the 55v line voltage applies only to building site power supplies using a CTE transformer.

 

But if you are getting a true "line, neutral, Earth" 100v~120v supply the shock is far more likely to kill you than a 220v~250v shock, both assuming you have assistance within a very few minutes 

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@kuzmabruk you still there?

Was thinking about the IoT and I have a setup where I can remotely switch pool lights from my smartphone. You could just buy one of those wifi enabled power switches and plug your fridge into it. You can then switch power to your fridge on and off via your phone and get a visual of when the power is on or off.
The reason I said maybe faulty installation is as my electrician was excellent at factory installations and 3 phase work, but didn't know about SafetyCuts, or stabalisers and how to wire them. His theory was that you don't use SafetyCuts because they trip. So he wired it incorrectly and it tripped every couple of days.
With help from Crossy et all. we sorted out the wiring problem and now it doesn't trip. (except for very close lightning strikes and real faults.)



Sent from my SM-J700F using Tapatalk

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9 minutes ago, carlyai said:

Was thinking about the IoT and I have a setup where I can remotely switch pool lights from my smartphone. You could just buy one of those wifi enabled power switches and plug your fridge into it. You can then switch power to your fridge on and off via your phone and get a visual of when the power is on or off.

But when his Safety Cut trips its game over along with said remote switch.

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'But when his Safety Cut trips its game over along with said remote switch.'

 

Yes, switch can't be contacted therefore indicates power off.

 

 

 

Sent from my SM-J700F using Tapatalk

 

 

 

 

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5 minutes ago, carlyai said:

'But when his Safety Cut trips its game over along with said remote switch.'

But won't it show 'OFF' on the smartphone app.?

Sent from my SM-J700F using Tapatalk
 

It would if all components were battery backed.

 

I can see your point though. Some kind of remote monitoring of the condo would be nice for someone away lots.

Edited by Fruit Trader

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As noted previously correct solution is to determine why the beast is tripping, but this may be easier said than done as it's not happening particularly regularly.

 

Also, arranging the freezer and fridge to be on a circuit that doesn't involve the RCD/RCBO will solve the issue no matter why the RCD trips out.

 

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18 hours ago, Crossy said:

 

OK, that is a 30/100 meter, somewhere between it and the rest of the installation should be a 100A breaker or HRC fuse.

 

Can you sketch out your internal distribution system. I am seriously worried about the size of your sub-main wiring. I wouldn't have any subs of less than 10mm2 with a 50A breaker protecting the supply end.

 

The problem is that, once you have a permanent supply (4 Baht per unit) you can pretty much do what you like until you melt the meter (300A+). Also, unlike the UK, there is no DNO fuse. Short your incoming supply and the only overcurrent protection is the X00A drop fuses that protect the transformer.

 

I do have a HRC fuse found it yesterday. In a box right under the roof in the Thai kitchen. I also sorted how much power goes to the T/Cut out, it's around 25% the rest going to the rear of house with its 5 C/B boxes. That has all the fridges and freezers. The front part only has LED lights TV and sockets they only power the odd fan.

 

This morning at great expense I changed the Cut out. took me around 20 min: Did that with the aid of an extension lead running from the back of house powering a lamp: I did it without turning off the power. Simple enough the only problem was clipping in the new set up. A bit of faffing about. So far so good all working well. 

With the cut out set at 10 this new one has a setting of 5/10/30 old one 10/20/30/

Edited by fredob43
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On 4/12/2019 at 4:34 AM, carlyai said:

The OP typed. 'It is tripping very often (once every 1-2 weeks).'

I think you also have to answer the question, "has it always tripped?"

If the answer is 'yes' then it could be a faulty installation from the start.

If the answer is "no", then it could be a genuine fault.

You could also install one of those Internet of Things (IoT) wifi switches and a sensor to tell you when the power has failed or room temperature is high, and sènd you a message. Then get one of the staff from 'We Are Number One' to go and reset the Safety Cut. :)

There's a aircon shop near the cornor of Jontimen road and Theppasit rd. They seem to do a fair aircon job, but may know of an electrician. Take a photo of the Safety Cut with you to show them. Emphasise that the electrician must know about SafetyCuts and has the tools Crossy recommends.

Sent from my SM-J700F using Tapatalk
 

carlyai

 

Thank you, I went to the air con shop today and they are coming on Monday to check.

FYI, here are their contact details

Kongmun Group

Kate @ 038-251-888

kong-mun@hotmail.com

 

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On 4/12/2019 at 11:05 AM, Fruit Trader said:

It just might be something outside of the condo installation tripping the device. Nuisance trips can come from external sources.

 

Leaving the circuit for your refrigerator active and disconnecting the rest might add some clues if you want to do some DIY testing.

 

You can discuss this over many pages but as already mentioned, the installation first needs testing to see if there is any leakage lurking just below the trip level.

 

If you want an electrician with proper test gear, the best place to ask is at one of the electricians supply stores scattered around the Pattaya area. If you cant speak Thai you will need someone to translate and explain the need for someone with proper test equipment. They do exist.

 

Re surge protection. A good electrician will also help with adding surge protection to your installation. A lot of suppliers around Chonburi are now stocking modular high power surge protectors.

Fruit Trader, thanks for your input

 

I have found a whole house surge protector, Intermatic Smart Guard IG2240-IMSK for THB 9,962 from Ubuy.  Good American made technology.  Designed to protect air con units, and all other expensive electronic gear in your home.

https://www.intermatic.com/-/media/inriver/10230-11160.ashx/Surge Family Brochure

 

image.png.aa67f4749bacb58956f7c2cb6195ed8b.png

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On 4/12/2019 at 10:58 AM, Crossy said:

 

How have you determined that the RCBO unit is faulty from the information given? The unit may well be faulty, but simply bypassing it isn't a fix, it's a bodge to get the power back in in an emergency, and it's not going off particularly regularly anyway.

 

I suspect that there's a N-E fault on a little used circuit which only causes issues when there's a particular set of loads. Not an easy diagnosis (and you have to find the fault to fix it) but a competent sparks (good luck there) with the correct gear should be able to at least isolate which circuit is at fault.

 

Crossy, I have an electrician coming on Monday.  Hopefully he can determine whether the unit is faulty or an improper installation, etc.  I do NOT want to remove it as it is there for a good reason.

 

That said, I am going to install a whole house surge protector and since the biggest problem is the fridge shutting off while I am away I will take the suggestion that a few people have made and wire a small panel with a single breaker in it off of my main power - before my Safe-T-Cut and plug the fridge into that.

 

My plan is:

 

1. main power int

2. whole house surge protector

3. inline sub-panel for fridge

4. safe-t-cut

5. current panels/breaker setup

 

Here is the main 75A breaker outside my condo, split off to two 60A services.

 

944935595_2019-04-1715_10_40.thumb.jpg.f92ca3dcd42688bec7cd971c18658848.jpg

 

Here is my power closet, with my Safe-T-Cut, 2 main panels and my lighting sub-panel and dimmer switch sub-panel.

 

1867795228_2019-04-1814_07_03.thumb.jpg.462d69c41a13e165e71affedf6ce3ef9.jpg

 

Here is my Safe-T-Cut, set to 30

 

251950947_2019-04-1814_07_32.thumb.jpg.a64934837b925f3956692e430e7d81c2.jpg

 

Any more ideas before the electrician arrives will be greatly appreciated. 

 

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Is there a way to check if an RCBO is broken or must one simply replace it to find out?  If the earth wire is not 'earthed' will this cause the RCBO to trip?  Why do some RCBO units have a simple line in, live and neutral, and others have the earth line connected to the device also?  Is there a simple way to test the earth wire to confirm that it is actually earthed?  (What a lot of questions.)  Thank you very much for any comments.

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24 minutes ago, notrub said:

Is there a way to check if an RCBO is broken or must one simply replace it to find out?  If the earth wire is not 'earthed' will this cause the RCBO to trip?  Why do some RCBO units have a simple line in, live and neutral, and others have the earth line connected to the device also?  Is there a simple way to test the earth wire to confirm that it is actually earthed?  (What a lot of questions.)  Thank you very much for any comments.

Pushing the "Test" button should cause the RCD/RCBO to trip.  That indicates the unit is working.  No trip indicates the unit is not working.

 

Earth does not affect RCBO operation.  It works the same whether earth is present or not.

 

GFCI (common in the states) will have earth connected because they are point-of-use receptacle.  I'm not aware of the usual RCBO found in Thailand to require earth connection.  Do you have photo or snip of such?

 

A simple way to "test" earth is to check voltage between L-E in the CU.  If that shows voltage close to the L-N voltage, it's a good bet the earth is OK.

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