Grounding AC's

[r136dg]

I'm sure this is a greenhorn question. Anyways, when wiring the house I ran ground wires to just about everything, including where the ac's would be parked. Just had a couple Daikin inverters installed today and there was only live & neutral wires from them. Since I have the ground wires right there would it be good practice to ground the frames or anything, and out to the compressor frames maybe? Or would that be a complete waste of time? I suppose this question would apply to other things that have no ground wires coming out of them like our bathroom exhaust fans. Everything in the bathrooms are on RCBO's if that's relevant, the ac's are not.

Thanks in advance!

[Crossy]

Are you quite sure there is no ground connection, look in the installation manual.

 

Metal cased appliances are rarely (if ever) double insulated.

 

If they had pre-installed tails to connect to the supply, I'll lay odds that if you pop off the cover there will be an (unconnected) ground there all lonesome.

 

If they do turn out to be double insulated do NOT connect ground wires.

[r136dg]

A little research showed me class II (double insulated) appliances don't/shouldn't be grounded. I believe class II's are encased in plastic. Internet research, so ???

The manual's in Thai, I tried extracting info from it yesterday but will have my wife help with that later today and I'll look best I can into the installed units. There might even be a class II stamp on them somewhere.

The bathrooms exhaust fans are encased in plastic so I would assume they're class II & shouldn't be grounded. ???

Thanks much Crossy!

 

 

[Crossy]

A Google of the model number should net you an English installation manual.

 

But the Thai one should have the interconnection diagram.

[Dazinoz]

Grounding/earthing is certainly not worried about in Thailand. The last townhouse I rented was extensively renovated including some new wiring before I moved in. The switchboard is located in the middle of the house so they drilled a hole through the concrete floor and drove earth stake in. After moving in I checked a few things especially the shower water heaters. Downstairs one ok but I had a low voltage reading between active and ground indication a poor ground connect. Later I got into the roof space and discovered why poor ground connection. Ground wire from heater twisted around reo bar sticking out of wall. 

[Foozool]

Whether it is double insulated or not you have nothing to lose. Just Earth the body if you feel safer. 

[r136dg]

Turns out there's a place to park grounds inside the compressors & in the indoor units. I think these guys are just to lazy to hook it up, even when the wire's right there in their face. I was persistent yesterday asking them why they weren't grounding anything. I'm sure you know the response I got; "no no, mai bpen rai".

I'm really burning out on poor workmanship & the messes they leave behind.

Thanks for the heads up Crossy! It was misleading with only live & neutral wires coming out of the units.

[Dazinoz]

1 hour ago, r136dg said:

 

I'm really burning out on poor workmanship & the messes they leave behind.

 

 

They don't care. Everything works without ground wire so why waste time and money to install it.

[Crossy]

21 hours ago, Dazinoz said:

Later I got into the roof space and discovered why poor ground connection. Ground wire from heater twisted around reo bar sticking out of wall. 

 

The annoying part is that re-bar is probably a very good ground, it was the crumby connection to it that was the issue.

 

Google "Ufer ground", our roof steel measures better than our actual ground rod.

 

[williet98248]

Just rewired the wife's farmhouse with three wire cable.  Hired in a Thai electrician.  Good knowledgeable guy.  He insisted  I install a meter and a half ground stake instead of the one meter one I provided.  A main breaker box upstairs and a satellite one just for the kitchen circuits, also grounded with its own GS.   Not 'everything works' without a grounded circuit.    My Apple computer and new washing machine will not work in an ungrounded circuit as well as some kitchen appliances.

[GaryB1263]

That's encouraging Williet. Always good to hear about some Thais understand grounding.

[r136dg]

30 minutes ago, Crossy said:

"Ufer ground", our roof steel measures better than our actual ground rod.

What if you ran the ufer ground & ground rod to your distribution box. Would that measure any better?

[Crossy]

1 hour ago, r136dg said:

What if you ran the ufer ground & ground rod to your distribution box. Would that measure any better?

 

That's how we are wired, the measurement with both together is very slightly better than the roof alone, but the difference is really within the measurement error of my meter.

 

Both PEA and MEA inspectors expect to see a rod, Ufer (concrete encased electrode) grounding is not mentioned in the Thai regulations.

 

 

[StevieAus]

1 hour ago, Crossy said:

 

That's how we are wired, the measurement with both together is very slightly better than the roof alone, but the difference is really within the measurement error of my meter.

 

Both PEA and MEA inspectors expect to see a rod, Ufer (concrete encased electrode) grounding is not mentioned in the Thai regulations.

 

 

I bought a Samsung refrigerator with an invertor that came with a two pin plug but a separate earth wire which the instructions called to be connected to an earthing rod

This wasn't a problem as it was for use in a downstairs under cover eating area

Is this usual and how would you earth it if it was inside the house ?

[janclaes47]

4 hours ago, Crossy said:

 

The annoying part is that re-bar is probably a very good ground, it was the crumby connection to it that was the issue.

 

Google "Ufer ground", our roof steel measures better than our actual ground rod.

 

Does that apply to every house, or does there need to be a dedicated ground wiring under the foundation?

[bankruatsteve]

7 minutes ago, StevieAus said:

I bought a Samsung refrigerator with an invertor that came with a two pin plug but a separate earth wire which the instructions called to be connected to an earthing rod

This wasn't a problem as it was for use in a downstairs under cover eating area

Is this usual and how would you earth it if it was inside the house ?

There are several threads on this.  If the power point is earthed (3-prong receptacle), then it's just a matter of connecting the separate ground wire from the fridge to the ground in the receptacle.  Several ways to do that but basically, that's it.

[janclaes47]

17 minutes ago, Arjen said:

Average they say: here: you need a ground rod from 500mm, 1.000mm or even more. But the only way to find out is measure your resistance to ground. This is a complicated measurement. For measuring you need to add three more ground rods. and you need to measure the resistance between these rods.

 

I once whitnessed this process, and it took a long time before correct measurements where achieved. (that was back in my home country) a few meters below sea level, and close to the sea. (800 meters or so) This makes you think that earthing is not difficult. But it turned out it was......

 

But people like Crossy can tell all details for sure.

 

Arjen.

 

 

 

My question was actually regarding using the roof connected to the foundation as ground.

 

I have ground rods of 3 meter, but if i connect something in the loft it would be much easier to use the roof steel as ground.

[Crossy]

1 hour ago, janclaes47 said:

Does that apply to every house, or does there need to be a dedicated ground wiring under the foundation?

 

A good and difficult question.

 

To be sure you really need to measure the ground resistance, which, as others have noted, needs specialist equipment. If you know your re-bar is continuous from the roof to the foundations then there's a strong chance it will be a fair ground.

 

Which is of course, why I said "probably".

[StevieAus]

2 hours ago, bankruatsteve said:

There are several threads on this.  If the power point is earthed (3-prong receptacle), then it's just a matter of connecting the separate ground wire from the fridge to the ground in the receptacle.  Several ways to do that but basically, that's it.

I used a separate grounding rod as per the instructions as it wasn't in the house

I was curious as to why it didn't just come with a thre pin plug and was this because it had an inverter?

[janclaes47]

2 minutes ago, StevieAus said:

I used a separate grounding rod as per the instructions as it wasn't in the house

I was curious as to why it didn't just come with a thre pin plug and was this because it had an inverter?

My guess is that it doesn't come with a 3 prong plug because the majority of houses in Thailand don't have 3 prong sockets.

 

Adding to that is that my understanding is that if you have a properly functioning RCBO on your electrical circuits you don't actually need grounding.

[Dazinoz]

3 hours ago, StevieAus said:

I bought a Samsung refrigerator with an invertor that came with a two pin plug but a separate earth wire which the instructions called to be connected to an earthing rod

This wasn't a problem as it was for use in a downstairs under cover eating area

Is this usual and how would you earth it if it was inside the house ?

 Same here. Bought a couple months ago. I did think when I plugged in why only 2 pin plug. Had a few issues in my life since so never gave it another thought until i read your post. Just checked, ground connection symbols stamped into the metal everywhere at the back. Earth/ground wires running from base to compressor to cabinet but none to outlet so in the process of doing so.

 

I guess this shows up something about the law in Thailand too. I know if a company did this in Australia and someone was electrocuted the company could be sued for heaps. They would provide a 3 wired grounded plug and if, as in the case of a lot of places in thailand, there is no 3 pin outlet and the owner cuts off the 3rd pin then it becomes their responsibility not the fridge manufacturer.

[Dazinoz]

27 minutes ago, janclaes47 said:

Adding to that is that my understanding is that if you have a properly functioning RCBO on your electrical circuits you don't actually need grounding.

 

Technically that is true but don't forget that an RCD requires you to receive the shock before it trips, so if you are not a typical healthy adult, the RCD will probably not trip fast enough to save you. Children, the sick, the old or pets are typically not able to sustain the shock that a RCD allows before tripping. Plus the shock could throw you back and sustain injuries in doing so. I know from a personal experience of this.

[Crossy]

+ many, many @Dazinoz

 

The 30,30, 30 (30V, 30mA, 30ms) rule was chosen to be non-lethal to the majority of healthy adults without being excessively prone to nuisance trips.

 

A functioning earth, even if not a very good one, will ensure the RCD trips before anyone gets zapped.

 

[janclaes47]

2 hours ago, Crossy said:

+ many, many @Dazinoz

 

The 30,30, 30 (30V, 30mA, 30ms) rule was chosen to be non-lethal to the majority of healthy adults without being excessively prone to nuisance trips.

 

A functioning earth, even if not a very good one, will ensure the RCD trips before anyone gets zapped.

 

Can you elaborate on that last sentence?

 

When I had my electrical installation tested they tested both RCBO and earth separately, and I was told that the RCBO didn't need an earth to work properly.

 

So if I had no earth the RCD's I have would deliver me a zap?

 

 

[Crossy]

@janclaes47

 

Consider a Class-1 (metal cased) appliance with no earth connected.

 

If it develops a L-E fault the metalwork becomes live.

 

With no RCD. Touch it, a current limited by your body resistance flows and you die.

With an RCD. Touch it, a current limited by your body resistance flows, 30ms later the RCD opens and you probably don't die.

 

With a ground, a current limited by the earth resistance flows directly to earth, it may (or may not) be enough to open the MCB.

With an RCD AND a ground, the current flows directly to earth, the RCD opens without you being involved in the circuit.

 

The RCD needs 30mA to open, at 220V 30mA will flow if the resistance is less than about 7,000 Ohms (that's a pretty poor earth). Even a simple earth should get you below 100 Ohms.

 

 

[wpcoe]

3 hours ago, StevieAus said:

I used a separate grounding rod as per the instructions as it wasn't in the house

I was curious as to why it didn't just come with a thre pin plug and was this because it had an inverter?

By any chance was the "two pin" plug a Schuko plug?

 

 

I think these are less common in Thailand these days, but maybe worth asking?

[Dazinoz]

46 minutes ago, wpcoe said:

By any chance was the "two pin" plug a Schuko plug?

 

 

I think these are less common in Thailand these days, but maybe worth asking?

My new Samsung fridge has a normal 2 pin plug. I have seen these Schuko plugs, in fact my induction hotplate has one, but not sure how they worked. Now I know. I was thinking maybe you could buy an earth pin and push into 3rd hole and make it a 3 pin plug.

 

I have run an earth wire from behind the power outlet to my fridge until i go buy a 3 pin plug and connect it.

 

On a side note, just remembered at my second house I rented an earth wire had been run to the outside washing machine. Not very effective as it was screwed into the plastic control housing. No, there was no metal behind the screw. 

[Crossy]

2 minutes ago, Dazinoz said:

I was thinking maybe you could buy an earth pin and push into 3rd hole and make it a 3 pin plug.

 

Sadly the hole doesn't line up with the ground pin in a Thai outlet, you can get an adapter with a third pin but they are seemingly getting rare, or you can get a Schuko outlet which will fit a Thai back box.

 

Once the guarantee is out replace the Schuko with a Thai 3-pin plug.

 

 

[Dazinoz]

1 minute ago, Crossy said:

 

Sadly the hole doesn't line up with the ground pin in a Thai outlet, you can get an adapter with a third pin but they are seemingly getting rare, or you can get a Schuko outlet which will fit a Thai back box.

 

Once the guarantee is out replace the Schuko with a Thai 3-pin plug.

 

 

Hadn't looked at the alignment.

 

And speaking of warranty I guess I should leave manufacturers plug on fridge. I will just connect earth in a second plug. Not ideal I know but makes safe and keeps my warranty.

[wpcoe]

To round out this side discussion about Schuko (and since I have the pics handy), here are a Schuko outlet and the increasingly elusive Thai adapter: