Drawing Too Much Electricty / Consumer Unit / Plastic Consumer Unit Box

[Cashboy]

In the UK, under what ever directive (I think 17th) it is compulsaory to use a metal consumer unit box.

 

I took a few Schneider Consumer Units to Thailand from the UK.

They are plastic as per picture with the standrd 2 RCDs and MCBs

I also took some 10 Amp and 20 Amp MCBs as seem to be commonly used in Thailand.

 

Is there any rules in Thailand regarding using a plastic consumer unit?

I actually feel that they are safer than a steel one.

 

 

 

I intend to use two of these consumer units.

One for upstairs and one for downstairs (2 floor house)

 

I shall supply both of them from a single 63 Amp MCB worrying about overloading the Mains Supply Cable.

 

I am running the following off the two consumer units:

 

DOWNSTAIRS:

Shower 4500 watt

Expresso Coffee Machine  4200 watt

Water heater  2000 watt

UK electric kettle 3000 watt

Air conditioning Unit

 

UPSTAIRS

2 No Showers 4500 watt

2 Air Conditioning Units

 

Am I overloading my supply?

This is the reason for putting a 63 Amp MCB on the Mains Supply.

 

 

 

[sometimewoodworker]

34 minutes ago, Cashboy said:

Is there any rules in Thailand regarding using a plastic consumer unit?

I actually feel that they are safer than a steel one.

No problem, all my CU’s are plastic.
 

and you are not stressing your supply.

[daveAustin]

Plastic is a fire hazard.

[sometimewoodworker]

3 hours ago, daveAustin said:

Plastic is a fire hazard.

Not the plastic used in those as it’s self extinguishing. But your point is?

[Crossy]

My CUs are all plastic too. The UK regs actually specify "non combustible" which everyone reads as "metal".

 

With a 63A incoming MCB and a 15/45 meter you won't be overstressing the supply.

 

Do you have a permanent meter yet? If not the PEA inspector may not like the 63A incomer, just replace it with a 50A unit until he's gone ????

 

Also, ensure you wire to Thai requirements, the UK regs are very good but things like ring-finals are a no-no, AS3000 (Aussie regs) is actually a better fit for here.

 

A handy-dandy PEA document Groundwire Mk2 book-Manual.pdf

 

And the important bit with translations, note the routing of the incoming neutral via the ground bar, this is the Thai implementation of MEN (similar to PME).

 

 

 

[Chazar]

12 hours ago, Cashboy said:

metal consumer unit box.

seen a  few  videos  saying this is  nonsense and useless from UK electricians

[Cashboy]

On 12/8/2019 at 10:19 PM, Crossy said:

 

Also, ensure you wire to Thai requirements, the UK regs are very good but things like ring-finals are a no-no, AS3000 (Aussie regs) is actually a better fit for here.

 

What do you mean by "ring-finals are a no-no"?

 

Do you mean running a 2.5 mm2 ring from the consumer unit with a 30 Amp MCB is not legal in Thailand

 

I have about 80 (4" x 4") metal boxes in the house for power, with each box taking 4 electric sockets in.

So if I was running it on a 20 Amp MCB, how many of these metal boxes (with 4 electric sockets in) can I connect to one 20 Amp MCB?

 

[Cashboy]

On 12/8/2019 at 10:19 PM, Crossy said:

 

 

 

 

That does not make sense to me !

In the UK after the meter, I have the live and neutral going to the consumer unit and the earth connected to the armour plating of the incoming mains cable.

The neutral mains is NOT connected to the earth in my UK house as far as I can see.

 

This was my plan:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[bankruatsteve]

15 minutes ago, Cashboy said:

What do you mean by "ring-finals are a no-no"?

 

Do you mean running a 2.5 mm2 ring from the consumer unit with a 30 Amp MCB is not legal in Thailand

 

I have about 80 (4" x 4") metal boxes in the house for power, with each box taking 4 electric sockets in.

So if I was running it on a 20 Amp MCB, how many of these metal boxes (with 4 electric sockets in) can I connect to one 20 Amp MCB?

 

Ring-finals are mostly an English thing.  If not expected, they can be hazardess to the unknowing spark.

With 80 boxes, you would want as many circuits as you can support.  It's not the count, but what you anticipate plugging in that will determine.

 

[sometimewoodworker]

1 hour ago, Cashboy said:

What do you mean by "ring-finals are a no-no"?

 

Do you mean running a 2.5 mm2 ring from the consumer unit with a 30 Amp MCB is not legal in Thailand

 

I have about 80 (4" x 4") metal boxes in the house for power, with each box taking 4 electric sockets in.

So if I was running it on a 20 Amp MCB, how many of these metal boxes (with 4 electric sockets in) can I connect to one 20 Amp MCB?

 

Ring finals are even deprecated in the UK. It’s quite possible that they may even be banned for new builds in the not too distant future 

 

They have a 32Amp requirement. Split the ring and each radial gets a 20Amp to 25Amp breaker, so you have immediately gained an extra 8Amp to 18Amps available.

 

The numbers of sockets you can put on radials is basically unlimited (even in the UK). However the load should not exceed 25Amps for an extended period, so the number of sockets is most often limited by that requirement.

 

As to why ring finals are a bad (arguably very bad to stupid idea) 

1) find any electrician here who can understand them.

2) find any electrician here who can install them

3) find any electrician here who can trouble shoot them when the installation goes wrong

4) find any electrician here who can check to see if they have been installed correctly. (Sometimes even a challenge in the UK)

5) and most importantly ring finals have different failure modes that are very capable of leaving appliances apparently off but in fact they are at 220V as the ring has failed in an exciting (for someone watching who has a life insurance policy on you) ???? way. 

 

 

 

[Crossy]

1 hour ago, Cashboy said:

Do you mean running a 2.5 mm2 ring from the consumer unit with a 30 Amp MCB is not legal in Thailand

 

Correct! Thai plugs are un-fused and rated at 16A. There's no protection for the appliance flex other than the MCB (your 0.5mm² fan flex is going to be glowing before a 30A breaker operates). Run 2.5mm² radials on 20A breakers like everyone else, just run more of them.

 

1 hour ago, Cashboy said:

The neutral mains is NOT connected to the earth in my UK house as far as I can see.

 

But you can't see in your service head. Having TN-S in the UK is becoming increasingly rare, a massive number of supplies are now TNC-S (with the N-E split in the service head) mainly due to the deterioration of the cable armouring which was providing the earth path.

 

Your plan actually looks pretty OK, close to what we have, just make your N-E connection on the incoming side of your changeover switch and you'll be good to go. Make it look like the Thai authorities want and they will be happy.

 

I would put the 63A MCB on the supply side of the changeover otherwise there's no protection for the switch (no DNO fuses here).

 

EDIT It's also worth noting that the inspector is going to want to see some form of earth leakage protection. If you're not going for multiple RCBOs then stick an RCD on the load side of the 63A breaker.

 

EDIT 2 Looking back I see those CUs have dual RCDs - Perfect!

You may want to adjust the RCD positioning to enable an un-protected circuit for your freezer ????

 

[Crossy]

Also:-

 

Run 6mm² for your showers and water heater, you won't need it for the 4.5kW unit but after a few chilly nights you may want to upgrade (we have an 8kW unit in the master bathroom).

 

Run individual radials for your aircons, 2.5mm² and 20A breakers will be fine unless they are huge units.

 

 

[Cashboy]

52 minutes ago, Crossy said:

 

I would put the 63A MCB on the supply side of the changeover otherwise there's no protection for the switch (no DNO fuses here).

 

The reason that I was putting the 63A MCB after the changeover switch (125 Amp) was to protect the amount of ampage drawn out from either the Mains or the Generator.

 

When I look at that government drawing connecting the Neutral to the Earth, I cannot see the reason for having an earth rod as it appears the earth is travelling to the government neutral anyway.

 

 

[bankruatsteve]

5 minutes ago, Cashboy said:

When I look at that government drawing connecting the Neutral to the Earth, I cannot see the reason for having an earth rod as it appears the earth is travelling to the government neutral anyway.

MEN: Multiple Earthed Neutral

The CU is a critical point.

[Crossy]

9 minutes ago, Cashboy said:

The reason that I was putting the 63A MCB after the changeover switch (125 Amp) was to protect the amount of ampage drawn out from either the Mains or the Generator.

 

When I look at that government drawing connecting the Neutral to the Earth, I cannot see the reason for having an earth rod as it appears the earth is travelling to the government neutral anyway.

 

Is your genset really going to be able to open a 63A MCB? I would protect it separately with a suitable MCB.

 

Thailand uses the MEN (Multiple Earthed Neutral) system (like Aus and NZ), the neutral is grounded at multiple points, at the installation and at every 3rd pole or so. This is to mitigate the hazard from an open neutral in a TNC-S system.

 

If you really don't like it then once the inspector has gone convert to TT.

 

 

[bankruatsteve]

2 minutes ago, Crossy said:

Is your genset really going to be able to open a 63A MCB? I would protect it separately with a suitable MCB.

Most (all?) gensets have internal circuit breaker rated to capacity.

[Cashboy]

1 minute ago, Crossy said:

 

Is your genset really going to be able to open a 63A MCB? I would protect it separately with a suitable MCB.

 

Thailand uses the MEN (Multiple Earthed Neutral) system (like Aus and NZ), the neutral is grounded at multiple points, at the installation and at every 3rd pole or so. This is to mitigate the hazard from an open neutral in a TNC-S system.

 

 

Generator, if I get one, would be maximum 9 kW so I see your point there.

 

I shall put the rod in then, I think they come in only 2 metre lengths in Global House.

 

 

 

 

[Cashboy]

14 minutes ago, Crossy said:

 

Is your genset really going to be able to open a 63A MCB? I would protect it separately with a suitable MCB.

 

Thailand uses the MEN (Multiple Earthed Neutral) system (like Aus and NZ), the neutral is grounded at multiple points, at the installation and at every 3rd pole or so. This is to mitigate the hazard from an open neutral in a TNC-S system.

 

If you really don't like it then once the inspector has gone convert to TT.

 

 

I just finished watching a YouTube video on UK mains supplies and the guy seems to say TNC-S system is the safest.

I just never realised that the earth could be connected to the neutral or vise versa.

 

It makes me think that having an earth in your serial connections from your consumer unit is pointless (as just an additional neutral) and actually something else to potentially short with the live?

 

[bankruatsteve]

2 minutes ago, Cashboy said:

It makes me think that having an earth in your serial connections from your consumer unit is pointless (as just an additional neutral) and actually something else to potentially short with the live?

Neutral is the necessary current carrying part of connection to a load.  Earth does not carry current until fault condition sends safely to ground.

[Cashboy]

2 minutes ago, bankruatsteve said:

Neutral is the necessary current carrying part of connection to a load.  Earth does not carry current until fault condition sends safely to ground.

But the earth is going back to the consumer unit (as is the neutral) and they are connected to each other in the consumer unit in effect?

[bankruatsteve]

3 minutes ago, Cashboy said:

But the earth is going back to the consumer unit (as is the neutral) and they are connected to each other in the consumer unit in effect?

N does not carry a fault and E does not carry current from the load.  Both are necessary in circuits.

[Crossy]

10 minutes ago, Cashboy said:

But the earth is going back to the consumer unit (as is the neutral) and they are connected to each other in the consumer unit in effect?

 

In the past a TN-C system was permitted inside installations, the neutral provided the safety connection. It worked, and was reasonably safe (only relatively recently was it banned in the US). The issue was always that an open neutral interrupted the safety circuit, so no double-pole switches or MCBs.

 

Running a separate, continuous earth back to a central point in the CU is the way it's done pretty much everywhere now, TN-C is explicitly prohibited by all the regulations I have dealt with.

 

Have a look at AS3000 and see how the Aussies do it, very similar to Thailand.

[canthai55]

On 12/9/2019 at 5:19 AM, Crossy said:

And the important bit with translations, note the routing of the incoming neutral via the ground bar, this is the Thai implementation of MEN (similar to PME).

 

 

 

 

In the Groundwire link you provided there is no mention of depth for the ground rod. In rocky terrain can you bury the ground rod 1 meter below grade and lay it horizontally ?

[Crossy]

5 minutes ago, canthai55 said:

In the Groundwire link you provided there is no mention of depth for the ground rod. In rocky terrain can you bury the ground rod 1 meter below grade and lay it horizontally ?

 

It's not explicitly permitted, but once it's in and buried nobody will know.

 

If you do something that's a bit outside the (Thai) box make it look compliant (the inspector only does a visual) and test to ensure you have a good ground, all will be fine.

 

If I were installing in rocky terrain, I'd get a rod in as far as possible (for the inspector to see) and back it up with concrete encased electrodes (Google Ufer ground) as per the US NEC.

 

[bankruatsteve]

12 minutes ago, Crossy said:

In the past a TN-C system was permitted inside installations, the neutral provided the safety connection. It worked, and was reasonably safe (only relatively recently was it banned in the US). The issue was always that an open neutral interrupted the safety circuit, so no double-pole switches or MCBs.

My recollection is that in the 50's some mfg. used N to provide fault protection in some appliances and resulting in the standard for 2-pin receptacle/plug to fit only one way.  The NEC has never allowed bonding N to E in a circuit to wit.

[canthai55]

1 hour ago, Crossy said:

 

It's not explicitly permitted, but once it's in and buried nobody will know.

 

If you do something that's a bit outside the (Thai) box make it look compliant (the inspector only does a visual) and test to ensure you have a good ground, all will be fine.

 

If I were installing in rocky terrain, I'd get a rod in as far as possible (for the inspector to see) and back it up with concrete encased electrodes (Google Ufer ground) as per the US NEC.

 

Canada allows a copper plate in lieu of a ground rod in rocky ground. Did it at my last house build there, they wanted to see it before I buried it but all OK. 60cm square by 6mm

[bankruatsteve]

2 minutes ago, canthai55 said:

Canada allows a copper plate in lieu of a ground rod in rocky ground. Did it at my last house build there, they wanted to see it before I buried it but all OK. 60cm square by 6mm

You didn't have copper plumbing?

[Cashboy]

9 hours ago, Crossy said:

 

Run 6mm² for your showers and water heater, you won't need it for the 4.5kW unit but after a few chilly nights you may want to upgrade (we have an 8kW unit in the master bathroom).

 

Run individual radials for your aircons, 2.5mm² and 20A breakers will be fine unless they are huge units.

 

 

I have purchased 4.5kW electric showers ( 3 Number) that I think I shall find a luxury compared to no heated water as for the last 3 years.

When I rented condos in Bangkok, they were generally 3.5kw.

I was considering 6.0kw but was concerned that having three could overload the mains.

 

When I look at the installation instructions for the 4.5kw it states 2.5 mm2 or 4.0 mm2.  My intention was to use 4.0mm2 with 32 Amp MCB off the RCB.

[Metropolitian]

On 12/8/2019 at 5:11 PM, Cashboy said:

I took a few Schneider Consumer Units to Thailand from the UK.

They are plastic as per picture with the standrd 2 RCDs and MCBs
 

These are nice split consumer units you have there.

The Schneider MCB's are easily to get here.

Would advice to change some of the mcb's and the order. Are the one in the other units the same?

 

What I see there is : 6 - 6 - 16 - 20 - 32  RCB 6 - 6 - 16 - 32 - 32 RCB 20 - 20 - MAINB

 

What I would do with it: 6 for lights. 16 for outlets. 20 for air-con. 32 to the kitchen/pantry connected to a small mcb case with 3 or 4 mcb 16 amp for the kettle and hob. And the other 32amp to the kitchen and use a blue ceeform socket for that and your coffee machine.

Put the 63 amp (or get a 50amp) next to the main breaker, and connect that to the second floor consumer unit which has then  6, 16 and 20 amps mcb's for light, sockets and the air-con and heaters.

 

This should be sufficient but depends heavily on the demand factor.

A two person household wouldn't have everything on at the same time, changes are with a bigger family.

 

 

16 hours ago, Cashboy said:

What do you mean by "ring-finals are a no-no"?

Do you mean running a 2.5 mm2 ring from the consumer unit with a 30 Amp MCB is not legal in Thailand

Right. And better safe then sorry.. because..

15 hours ago, sometimewoodworker said:

As to why ring finals are a bad (arguably very bad to stupid idea) 

6) If the ring is broken somewhere, you wouldn't know and the equipment are still working, now when the disconnection is just in the beginning (or end if you look the other way round) and yet there is a heavy load device working, all the amp goes all the way round tough one wire and not shared. 

The only way to find this out is having a regular check, or when see your house lit.

 

 

 

16 hours ago, Cashboy said:

Is that 100 Amp switch a Chang knife cut-switch?

The earth rod need to go to the consumer unit, or next to it on a big bus bar, and there you can connect it to other boxes. At one point it need to be connected to the incoming neutral, a neutral that is NOT cut by the main breaker, so before it.  Crossy has a good drawing example of it in this thread.

The generator is better to also connected to a earth rod next to it to not disturb the neutral and earth in home with noise and spikes, and to not having a floating neutral when (dis)connect the generator to the system.

In the drawing the 63amp it says 80 amp out.

If that mcb is a din type mcb , move it to the first floor consumer unit for the second floor.

 

 

14 hours ago, Cashboy said:

When I look at that government drawing connecting the Neutral to the Earth, I cannot see the reason for having an earth rod as it appears the earth is travelling to the government neutral anyway.

 

Believe me, you need a earth rod.

If the neutral is cut outside, which can happen by several causes, then you don't have earth if you don't have a rod.

 

The regulations outside for the electric company is to have their transformer earthed and the neutrals too at some points (Crossy referred to a reg of every three poles need a link to earth from neutral) but the reality is that the electric company (here anyway) only connect the end points of the neutral lines at the poles.

 

To add: in my block there is nothing, the neutral lines don't have earth links and the transformer was replaced years ago and they probably forgot to reconnect the earth link. The only way the neutral get earth is from us, the consumers.

 

So, don't assume that the situation what you get is what the regs are.

Stay on the safe side, better comply to the regs and stay well between the lines.

 

 

[canthai55]

16 hours ago, bankruatsteve said:

You didn't have copper plumbing?

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