Does my CU set up comply with Thai regulation?

[jim234]

To my understanding, PEA will check the following;

 

Earth Rod

MEN link

Minimal use of 1 RCCB/RCBO (at front end)

 

After contemplating for a few days and searching on internet, I have decided on the following set up. Please comment if this will work in Thailand. Any suggestions are highly appreciated!

 

-> MEN link (incoming N goes to E bar before main switch)

-> 40A main switch, 400v (4P)

-> Six RCCBs 40A 30mA type A (2P)

-> Each RCCB feeds 4 MCBs 10A/16A/20A Curve B (1P+N) 

 

This will give me 24 circuits divided in 6 RCCB protected groups in a plastic (allowed?) DIN rail CU. A 3F set up that I am used to in Europe.

 

So no N bar is being used! (is this ok for PEA?)

 

I'm currently in Europe, so I plan to buy all materials here.

 

Any thoughts on this? Thank you!

[FritsSikkink]

Thought about any import duty / regulations?

[bluejets]

4 hours ago, jim234 said:

Any thoughts on this? Thank you!

Draw a diagram of your intended connections /breakers/main switch/ links etc. 

Following ones description can be misleading.

 

(1 example) ....Main neutral should not be switched and yes, there should be a neutral link bar as well as an earth link bar.

The MEN link is then, just that, a link between the two.

[motdaeng]

5 hours ago, jim234 said:

I'm currently in Europe, so I plan to buy all materials here.

i wouldn't do that! you can buy quality materials here in thailand, of course, at its price.

[Crossy]

This PEA document explains the minimum requirements, the OP seems to meet it.

 

Groundwire Mk2 book-Manual.pdf

 

BUT as @bluejetssuggests a diagram would be most useful.

 

Switching the N on a 3-phase supply is not usually recommended, you need a specific 4-pole breaker which connects N first and disconnects it last. Just use a 3-pole, it's easier and cheaper.

 

The important diagram, my translation.

 

[Crossy]

6 hours ago, jim234 said:

Each RCCB feeds 4 MCBs 10A/16A/20A Curve B (1P+N) 

 

Making everything 2-pole (or 1P+N) is going to confuse the heck out of the inspector (not to mention your sparking contractor).

 

A diagram may help but if you get a mean inspector ...

 

Personally, I'd stick to the standard Thai kit, single pole MCBs and multiple small ground bars for each RCD.

 

[jim234]

Thank you all for the replies so far!

 

Here is a diagram of a typical 3F set up that I´m use to, only the MEN link which I added is new to me.

 

 

6 hours ago, Crossy said:

Switching the N on a 3-phase supply is not usually recommended, you need a specific 4-pole breaker which connects N first and disconnects it last. Just use a 3-pole, it's easier and cheaper.

I still have a new 4P main breaker lying around here, thought of using that one. This complies with Dutch regulations.

 

If I use a 3P breaker, where does the N go? To a N-bar?

The diagram you shared (which is very helpful!) shows the N going through the main breaker too, right? Or what am I misunderstanding here?

 

6 hours ago, Crossy said:

Making everything 2-pole (or 1P+N) is going to confuse the heck out of the inspector (not to mention your sparking contractor).

Yes this is my main concern indeed.

 

7 hours ago, motdaeng said:

i wouldn't do that! you can buy quality materials here in thailand, of course, at its price.

the only RCCBs/RCCBOs I seem to find are Type-AC with C-curve. Type-AC is prohibited where I am from (safety issue) and C-curve is hardly being used in a domestic set up. 

 

I can find some Type-A´s on Lazada but they are all Chinese brands. Not sure if I feel comfortable with them.

 

8 hours ago, bluejets said:

(1 example) ....Main neutral should not be switched and yes, there should be a neutral link bar as well as an earth link bar.

The MEN link is then, just that, a link between the two.

yes I thought of linking the N bar with E bar, but when I see Thai regulation (also the diagram Crossy shared) I notice that the N goes through the main breaker first before a N bar is created.

 

6 hours ago, Crossy said:

Personally, I'd stick to the standard Thai kit, single pole MCBs and multiple small ground bars for each RCD.

That might be better then. So bring N through the RCD to create a seperate N-bar.

That means I will end up with 6 (or later more) N bars, no issues with that right? 

 

[KannikaP]

14 hours ago, jim234 said:

To my understanding, PEA will check the following;

 

Earth Rod

MEN link

Minimal use of 1 RCCB/RCBO (at front end)

 

After contemplating for a few days and searching on internet, I have decided on the following set up. Please comment if this will work in Thailand. Any suggestions are highly appreciated!

 

-> MEN link (incoming N goes to E bar before main switch)

-> 40A main switch, 400v (4P)

-> Six RCCBs 40A 30mA type A (2P)

-> Each RCCB feeds 4 MCBs 10A/16A/20A Curve B (1P+N) 

 

This will give me 24 circuits divided in 6 RCCB protected groups in a plastic (allowed?) DIN rail CU. A 3F set up that I am used to in Europe.

 

So no N bar is being used! (is this ok for PEA?)

 

I'm currently in Europe, so I plan to buy all materials here.

 

Any thoughts on this? Thank you!

Any thoughts? Yes, please turn your BOLD off.

[Crossy]

If your 4-pole incomer has a dedicated N way then no real reason not to use it. You could even make the N-E link after the breaker which would allow complete isolation from the outside world. Not sure how the inspector would react to that mind.

 

The diagrams in the PEA doc are single-phase of course where you DO switch both L and N lines.

 

Have a read of this page

https://www.electrolesk.com/Work/Wiring of Three Phase Distribution Board.htm

 

You need to do something like this with the added N-E MEN routing: -

 

[jim234]

4 minutes ago, Crossy said:

You need to do something like this with the added N-E MEN routing: -

Thank you! This is all clear now, except for the actual MEN link.

 

Can I just connect the Neutral CU bus bar link with the Earth bar as a MEN link? 

 

The PEA diagram shows the N going through the main breaker after the MEN link hence my confussion. So how is N going the the main breaker if it is not actually being switched? 

[Crossy]

Let me do a sketch once I get home, I don't have Visio on my office machine.

 

If you do it like the inspector is expecting then he will be happy.

 

The inspections usually are pretty minimal, if he sees what he expects to see. Ours was 30 minutes max, 25 minutes of which was him drinking coffee and gassing with Madam. He looked at the rod, and the MEN routing, noted our RCDs and moaned that the poles weren't straight.

 

[jim234]

5 minutes ago, Crossy said:

Let me do a sketch once I get home, I don't have Visio on my office machine.

 

If you do it like the inspector is expecting then he will be happy.

 

The inspections usually are pretty minimal, if he sees what he expects to see. Ours was 30 minutes max, 25 minutes of which was him drinking coffee and gassing with Madam. He looked at the rod, and the MEN routing, noted our RCDs and moaned that the poles weren't straight.

Thanks for that, I really appreciate it!

 

Yes, I agree with doing it like the inspector expects it to be done.

 

The main reason why I opted for using 2P MCBs is that I could only find C-curve MCBs in Thailand. 1P breakers are not available here in Holland, so I thought to bring 2P breakers instead. Anyways, I now understand that using C-curve is not a big issue, so I will buy my MCBs in Thailand. I probably will bring RCDs Type-A (and 1 Type-B for EV) to Thailand as I can´t seem to find them there.

[sometimewoodworker]

22 hours ago, jim234 said:

I can find some Type-A´s on Lazada but they are all Chinese brands. Not sure if I feel comfortable with them.

Just a point of clarification, Chinese manufacturers make top quality products, including rocket science, the problem is that they also make utter carp so you have to distinguish between the good, bad and deadly.

[MangoKorat]

On 9/25/2023 at 8:53 PM, FritsSikkink said:

Thought about any import duty / regulations?

I've brought in everything from a full house rewiring kit - sockets (UK), back boxes, plugs, cable....the lot, to a five burner gas hob and a kitchen extractor hood/fan.  This trip I brought in a full suitcase of automatic irrigation equipment - timers, valves, pipe and joints/couplings.

 

All of these packed in sturdy cardboard boxes and just sailed through customs. I think you'd have to be very unlucky to get pulled.

[jim234]

Thanks so far for all the help! Yet another question;

 

How much Amp is a typical 3 Phase supply in Thailand? 

 

Where I a from a standard 3 Phase supply is 3x25A. Therefore the main breaker and all RCDs are rated 40A. (Which also leaves room for a EV system per phase.) 

 

I still have quite a few new 40A RCDs and a main switch lying around here which I was planning to bring to Thailand. But reading through this forum makes me wonder if a 40A set up is suitable for Thailand. Many on here seem to use 63A (or even higher) as a main breaker. Why is that?

 

Am I safe to use a 40A set up in Thailand as shown in the diagram here below?

 

main breaker 40A, 400V

                     -------> RCD 40A, 30mA

                                   ------> MCBs not exceeding 40A (highest circuit + 40% of others)

I´ll be having 9 RCD groups in total

 

[Crossy]

You will likely get a 15/45 3-phase which is 45A per phase (usual incomer 50A - increase to 63A when the inspector has gone).

 

Have you done a prospective load estimate? Most of us manage on a single-phase 15/45 ???? 

 

Depending upon where you are you might be able to get a 30/100 single-phase supply, use a 100A incoming breaker ???? 

 

EDIT I must do that drawing I promised, sorry it's been chaos at work.

[Crossy]

2 hours ago, MangoKorat said:

I've brought in everything from a full house rewiring kit - sockets (UK), back boxes, plugs, cable....the lot, to a five burner gas hob and a kitchen extractor hood/fan.  This trip I brought in a full suitcase of automatic irrigation equipment - timers, valves, pipe and joints/couplings.

 

All of these packed in sturdy cardboard boxes and just sailed through customs. I think you'd have to be very unlucky to get pulled.

 

The customs chaps at the airport are on the lookout for easy pickings.

 

Over limit on booze or tobacco, there's no mechanism for paying duty so it's customs party time!

[jim234]

11 minutes ago, Crossy said:

EDIT I must do that drawing I promised, sorry it's been chaos at work.

  No worries, you have been very helpful already!

 

7 minutes ago, Crossy said:

You will likely get a 15/45 3-phase which is 45A per phase (usual incomer 50A - increase to 63A when the inspector has gone).

Does this mean if I have 50A or 63A main breaker, 40A RCDs are not safe to use? 

Do I need 63A RCDs instead? 

 

On 9/26/2023 at 9:39 AM, Crossy said:

 

I have noticed that there are 63A MCBs being used in front of the RCDs. 

 

Although we use 40A RCDs here, we never place a MCB in front of a RCD. Is this done because of the higher Amp?

 

[Crossy]

10 minutes ago, jim234 said:

Does this mean if I have 50A or 63A main breaker, 40A RCDs are not safe to use? 

Do I need 63A RCDs instead? 

 

In reality your 40A RCDs will be fine, they don't explode or stop working at 40.01A.

 

If worried keep the total of the breakers controlled by said RCD to <40A.

 

Putting an MCB in front of the RCDs seems like overkill although it does let you kill all juice to that section without turning off the whole installation.

[jim234]

7 minutes ago, Crossy said:

In reality your 40A RCDs will be fine, they don't explode or stop working at 40.01A.

 

If worried keep the total of the breakers controlled by said RCD to <40A.

The MCBs behind the RCD will be less than 40A. I calculate that by taking the highest MCB plus 40% of the value of the others. I believe that is the right way to do it, right?

 

17 minutes ago, Crossy said:

In reality your 40A RCDs will be fine, they don't explode or stop working at 40.01A.

If I do get a 45A supply on each phase, won´t that be an issue with the 40A RCDs? Thought that they won´t be able to handle that.....

 

or... the amp going through will never extend the amp of the demand? So even if the supply is 45A, that doesn´t necessary mean that 45A will pass the RCD, correct?

 

15 minutes ago, Crossy said:

Putting an MCB in front of the RCDs seems like overkill although it does let you kill all juice to that section without turning off the whole installation.

ok clear, thank you!

[Crossy]

1 minute ago, jim234 said:

The MCBs behind the RCD will be less than 40A. I calculate that by taking the highest MCB plus 40% of the value of the others. I believe that is the right way to do it, right?

 

Your idea of "diversity" seems fine to me.

 

3 minutes ago, jim234 said:

or... the amp going through will never extend the amp of the demand? So even if the supply is 45A, that doesn´t necessary mean that 45A will pass the RCD, correct?

 

Correct.

 

I really think that you are over-thinking here, you will end up with a vastly over-specified system, of course that won't hurt anything other than (maybe) your wallet.

 

Do a sketch of what you propose to do and let the brains that know analyse.

 

 

[jim234]

13 minutes ago, Crossy said:

I really think that you are over-thinking here, you will end up with a vastly over-specified system, of course that won't hurt anything other than (maybe) your wallet.

You are probably right on that one!

 

13 minutes ago, Crossy said:

Do a sketch of what you propose to do and let the brains that know analyse.

Will do, thank you!

[jim234]

2 hours ago, Crossy said:

Do a sketch of what you propose to do and let the brains that know analyse.

I am not very skillful with Paint but I hope the following sketch makes sense

 

 

The heaviest loads I have are two 32A´s, they are for ceiling cassette aircons. Two 20A loads are for the garden circuits, the other two for my workshop. Everything else is for inside the house.

 

I am aware of the MEN link, main neutral bar after main switch, and the appropriate size for wiring.

 

Am I good to go like this? 

 

 

[Crossy]

12 hours ago, jim234 said:

Am I good to go like this? 

 

I reckon you're pretty close.

 

A few thoughts: -

• Have you considered how to connect all those neutrals to the incoming neutral?
• Similarly, three lives to each of the incoming lives?
• You might want a non-RCD protected circuit for your freezer (coming home to a defrosted freezer in a tropical country is not fun). 
• Do think about adding lightning surge suppression.
• And under/over voltage protection.
• Are you considering solar?
• A backup generator?

You must have a pretty big place, running sub-mains and having local consumer units for each zone may prove more economical on cable. Same for the shed/man cave.

 

It's far easier to plan for expansion now than it is to expand a non-expandable system.

 

 

[jim234]

4 hours ago, Crossy said:

• Have you considered how to connect all those neutrals to the incoming neutral?
• Similarly, three lives to each of the incoming lives?

because of the size of the CU (3 boxes) I was thinking to go from one RCD to the next, so most RCDs will have 2 N´s and 2 L´s connected on the top of the RCD (is that called parallel?)

 

I could make a main N-bar and a L-bar for each phase, but because the size of the CU I thought that might get a bit messy

 

5 hours ago, Crossy said:

You might want a non-RCD protected circuit for your freezer (coming home to a defrosted freezer in a tropical country is not fun). 

that sounds like a good idea!

 

5 hours ago, Crossy said:

• Do think about adding lightning surge suppression.
• And under/over voltage protection.

I have no experience with both of them, I will look in to that.

 

5 hours ago, Crossy said:

Are you considering solar?

Yes, I do plan on adding a solar system. Not sure yet on the details. Once I have my CU sorted out I will read the solar forum on here!

 

5 hours ago, Crossy said:

A backup generator?

We are in Bangkok, so I reckon a generator won´t be necessary.

 

5 hours ago, Crossy said:

You must have a pretty big place, running sub-mains and having local consumer units for each zone may prove more economical on cable. Same for the shed/man cave.

Actually, that´s what I wanted to do, but reading through some forums discussing ¨selectivity¨ kind of put me off. Again, I´m probably overthinking things.

 

Please advise me on this;

 

If I want to place a second CU upstairs (approx. 15m from the main CU)

 

I assume I need to bring all 3 phases?

What size of cable do I need?

How to secure the 2nd CU in the main CU? With a MCB? Or can I just bring 3L+N straight after the main switch?

Does my 2nd CU need a main switch rated lower than the main switch in the 1rst CU?

Can the RCDs in the 2nd CU have the same rating as the RCDs in the main CU?

How many sub CUs can a system have? When does ´selectivity´ comes in?

 

It will indeed safe me quite a lot on cables and will make the overall installation easier!

 

[sometimewoodworker]

6 hours ago, jim234 said:

Please advise me on this;

 

If I want to place a second CU upstairs (approx. 15m from the main CU)

 

The general usage is, no you don’t need that. In general the vast majority of people here treat each phase as single phase after the main incommer. 
So you have a single phase for the ground floor, a different phase for the first floor and the third phase supplies the second floor.

 

The only exceptions are if you have 3 phase equipment, this is usually only for large 50,000BTU plus AC units 

If you have a machine shop with large fixed tools then you may want 3 phase motors but this is not a usual requirement.

@Crossy will give more information but I think that even he doesn’t bother with using 3 phase himself 

 

 

[jim234]

54 minutes ago, sometimewoodworker said:

The general usage is, no you don’t need that. In general the vast majority of people here treat each phase as single phase after the main incommer. 
So you have a single phase for the ground floor, a different phase for the first floor and the third phase supplies the second floor.

Thank you, that does make more sense!

 

My plan now is as follows;

 

-secure 1 phase in the main CU with a 40A MCB

-use a 10mm2 cable (L-N-E) to go upstairs to connect my 2nd CU

 

My 2nd CU will have;

-40A main switch

-40A,30mA RCDs  (total of 3)

-MCD not exeeding 20A    (total of 12)

 

Does this seem like a good set up? No ´selectivity´ issues here, right?

[sometimewoodworker]

The only other point that the PEA/MEA will want to see is that you have roughly balanced the load for each phase, so you can’t have one phase for your LED lights and the other 2 for the power equipment.
 

That is of course if you don’t have an indoor hydroponics weed grow operation so have huge numbers of lights ???????????? 

 

[jim234]

16 minutes ago, sometimewoodworker said:

That is of course if you don’t have an indoor hydroponics weed grow operation so have huge numbers of lights ???????????? 

Haha, I might be Dutch but have no plans in doing so (yet)

 

The load is been divided quite equally among the 3 phases. I assume the Earth bar from CU2 can be connected to CU1? No extra rod is needed, right?

[Crossy]

Yeah, just export your earth from CU1 to CU2, just one rod and one N-E bond.

 

I would feed the 10mm² to CU2 with a 50A breaker to give some discrimination but in the event of a short all bets are off as to which MCB will actually open first.

 

@sometimewoodworkerhas covered everything else I think.