Electricty Supply 220 Volt In Thailand

[Negita43]

My American neighbour keeps going on about the supply over here being 'Delta' can anyone explain to me what this means? Does this have any implications for wiring and especially EARTHING of my cabling.

[Crossy]

Supply in most of Thailand is 3-phase 4-wire or single-phase 2-wire, 220v 50Hz. There are a few remote villages that are 3-phase 3-wire (this is what your friend is calling 'delta') but they are few now.

As far as you need to be concerned your incoming supply will be 2 wires, live (or hot) and neutral. You will usually provide your own earth rod.

Have a look here http://www.crossy.co.uk/wiring/ and come back with any further questions.

If you believe you may be on a delta supply, have a look at your power poles in the street, how many wires? 3 wires would suggest delta, 4 would be the common arrangement. Post photos here if unsure.

[electau]

As Crossy states in the previous post. The LV distribution is 220/380V 3 phase 4 wire 50Hz and 220V 1 phase 2 wire 50Hz.

The HV windings are delta connected and the LV are star connected on a three phase distribution system and single phase ( two phases of the three phase HV distribution) with the neutral earthed.

There may be some 220V 3 wire systems that still exist but they are not common. Some may have 2 phases and neutral extended from a 3 phase and neutral system. It appears when one observes it they may mistake it for 3 wire 220V distribution.

As far as the consumer is concerned the supply will generally be 220V 2 wire, with a line (L) and neutral (N). The main earth and electrode forms part of the electrical installation.

Earthing may be TT or MEN.

[Negita43]

Thanks to both of you for that but what does

'Earthing may be TT or MEN' mean.

[Crossy]

Thanks to both of you for that but what does

'Earthing may be TT or MEN' mean.

Have a look here http://en.wikipedia....Earthing_system

MEN is a variant of TN-C-S and is explained with TN-C-S and expanded at the bottom of the page under Application Examples.

[Negita43]

Thanks crossy just read your link about electrics in Thailand very helpful tks

I am still not sure about 'delta' in my area I will photograph the cables and send them when I can

We have had a builders supply installed (what a laugh - I told the electrician who connected it I wanted the a trip and wanted it installed in a waterproof box - I'll send you a pic of the actual instalation to give you alaugh (except of course it's not funny) and the builder uses it by stuffing a live and aneutral into the output side of the bar switch!

Mike

[Crossy]

That sounds exactly like our construction supply, meter on the pole then a couple of 10mm² wires to a knife switch in a plastic bucket on the end of the workers quarters.

At least our chap put a couple of outlets on the board with the switch but the welder connected directly to the supply anyway.

Read all about it here

[electau]

Thanks to both of you for that but what does

'Earthing may be TT or MEN' mean.

TT earthing. The earthing system of an electrical installation is not bonded to the neutral of the distribution system.

MEN. The earthing system of the electrical installation is bonded to the neutral of the distribution system.

Both require a compliant main earthing conductor and electrode.

The MEN bond is generally at the main switchboard of a consumers electrical installation

The MEN system may be referred to as the PME in the UK, TN-C-S under IEC. or grounded neutral under the NEC code.

[electau]

The TT earthing system used to be known as direct earthing. The first type of earthing system earthed equipment directly to earth on an individual basis, later this became the TT system when all protective earth wires were taken to a common point and one main earth wire and electrode were used.

The TT system will protect by maintaining the voltage at less than 50VAC in the event of an earth fault on the earthing system. However the earth resistance of the earth conductor and main earth electrode is generally not low enough to operate a protective device , eg a circuit breaker (MCB) within the required time of less than 0.4secs in the event of an earth fault. Thus RCDs or RCBOs must be used to meet this requirement as they will operate with currents less than 30mA and less than 0.4 secs. With the TT system the fault current is carried by the main earth.

With the MEN system the fault current returns by way of the neutral to the point of supply. Fault currents are high but fault clearance times are less than 0.4secs. The main earth maintains the earthing system to less than 50VAC. The main earth and electrode carries neligible current.

Earthing will also minimise the effects of leakage currents from equipment.

In Thailand many electrical installations use the TT system or in may cases there us no earthing system at all and any earthing is carried out on an individual basis. The MEN system is being implemented on new electrical installations.

With the TT and MEN systems the distribution neutral from the point of supply, ie the transformer, is earthed at one or more points on the network.

[Negita43]

Hi Crossy Sorry for the delay in getting back to you on this. But the last 10 days have been fraught! We lost our builder! Or more correctly – he lost us – don’t know why- we paid him on time and gave him the odd advance when he pleaded poverty. Fortunately we didn’t lose any money in the matter. So for the last 10 days we have been searching for a new builder. Now we have one and in truth he seems (seems seems!!) better – no request for advance payment and better equipped and bigger team of men - so we will see. Now I can turn my attention back to DELTA. In your reply to me before you suggested some pics might help with an answer to ‘is it or isn’t it DELTA’ Here they are (and a pic of the waterproof box the electrician installed!!!!!! - IP45 or IP oilcan you think? And the FUSED breaker I asked for) Re the pics most are self explanatory but DSCF 5524 is where the supply for my street spurs off from the main grid (which looks 3 phase to me ??) IMG0192 is where my house takes its feed from this spur Based on what you have said before I would say that my supply is standard (ie live and neutral coming into the meter) what do you think? Thanks for you help Mike

[Crossy]

That looks like 3-phase 4-wire (Wye in US speak) to me, NOT delta.

Top (bare) wire of the 4 is the neutral.

IP rating of your oil can is better than my plastic bucket and those bits of 2.5 in the knife switch ARE the fuse

[electau]

As Crossy states.

The low voltage distribution is 3 phase 4 wire star ( wye), the bare conductor is the neutral.

The HV distribution is 3 wire delta.

Your supply is 2 wire single phase. The meter is a single phase meter with direct connected neutral. The main switch is a 2 pole 60A fused knife switch, the fuses should be HRC type not rewireable. It is not an MCB. It appears that both the line and neutral are fused.

[Negita43]

Thanks Crossy and Electau

I'm sorry to be so dim

is the upshot of what you say that the supply to my house will be single phase with a live and neutral

(ie the two wires from the meter to the blade switch) and does this mean I can use 2 core and earth to wire the house taking the earth to a common rail in the RCB BOX AND THEN FROM THERE TO (sorry about the caps - I HATE THIS BLOODY ACER 720) an earth rod in the garden

two questions where in my photos is the bare wire?

what is a HRC fuse?

Thanks again

Mike

[electau]

Yes you run the single phase 2 wire supply to a switchboard in your house. The Main Switch should be a 2 pole MCB. The neutral conductor terminates at the neutral bar or link before the main switch.

The main earth runs from the earth bar at the switchboard to an electrode, the PEA requirements is a copper clad steel 16mm x 2.4meters in the ground, so you will need a 3 meter electrode so the earth connection is accessable. The PE protective earths from equipment and 3 pin socket outlets run to the earth bar.

Because of the risk of reversed polarity on the incoming supply it is NOT advised to bond the earthing system to the main neutral. Your earthing system will be TT.

Clearly identify the neutral conductor at the meter and at the switchboard, the neutral terminals of the meter are the two centre ones. Correct polarity is L to N 220V, L to E 220V and N to E 0 volts.

RCDs (RCBOs) should be used on all circuits. ( GFCIs in US terminology)

(An HRC fuse is a special type of fuse with a very high short circuit rating in amps, used as a protective device for the incoming supply, they are not used for overload protection in this case).

The bare wire is the uppermost conductor on the LV distribution system, this is the neutral.

Edited October 23, 2012 by electau

[Crossy]

What he said ^^^

[Negita43]

Hi Electau and Crossy thanks again you're both a mine of info.

I have some copper clad earthing bars but they are only 1 meter long I'm not sure if they are steel core or aluminium core. If they are steel core can I weld 2 together (although this will damage the integrity of the copper cladding??).

Fianlly, Because of the risk of reversed polarity on the incoming supply it is NOT advised to bond the earthing system to the main neutral. Your earthing system will be TT. What is TT ?????

Thanks

[electau]

　

The correct size 16mm electrodes are available and only one is required, copper clad steel costs a lot less than solid hard drawn copper. You could use 20mm galvanised pipe. Do NOT use aluminium for an electrode. The PEA minimum size of main earth conductor is 10sqmm copper.

TT earthing system means that the earthing system including the main earth of your electrical installation is NOT connected to the incoming neutral conductor.

[kyrre]

Have modified one drawing and made some comments on it, and would ask of this would be the best metode to get a good and safe earthing system.

This is in Jomtien area, and i expect it to be live line + neutral.

Any suggestions or improvements. Ii TT or MEN the best system to use, ref this comments over:

Fianlly, Because of the risk of reversed polarity on the incoming supply it is NOT advised to bond the earthing system to the main neutral. Your earthing system will be TT.

Edited October 24, 2012 by kyrre

[Crossy]

If you're going for individual earth leakage protection on each circuit then you must use RCBO's (as they provide overload protection too).

Each circuit neutral must also pass through the RCBO so there is no longer direct connection to the neutral bar (the RCBO has a pigtail that you connect to the neutral bar instead).

If your house is already wired (by a Thai sparks) you will have almighty problems with borrowed neutrals causing your RCBO's to trip all the time, dashed annoying that.

Only install that N-E link (for MEN) if you KNOW that your area has been correctly configured for it, if in doubt leave it as TT.

[electau]

As Crossy states in the previous post.

　

The 2 pole utility isolator( main switch) should be a 63A MCB located on or adjacent to the main switchboard. Service fuses do not seem to be used in Thailand and their installation would be the reponsibility of the PEA. The MCB will give short circuit protection on the load side but not on the incoming line side. Mains should be PVC insulated PVC sheathed.

RCBOs can be 10mA or 30mA. Standard module width 18mm.

[Negita43]

Thanks everybody for your input.

I see in Kyrre's diagram that he shows the supply coming from a transformer. BUT there is no transformer within 1 mile radius of my house ( I know what they look like cos when I lived in the UK I had one on a pole in my garden).

My supply seems to come directly from the main supply wires in my street which in turn come directly from the grid (as per my pics to crossy). Does this make any difference to what you have all advised.

Finally, this is a new installation so I expect my 'fun' will be in preventing the Thai electrician from taking short cuts like stealing neutrals etc.

Isn't life exciting building a house in Tryland sorry Thailand?

Already my builder wants to fix the door frames with nails and cement and I want to fix with frames screws into block and concrete post (the reason for this is when my gf gets angry and slams the door I don't want a cascade of cement falling out).

[electau]

The transformer of which only the LV winding is shown with the earthing is part of the distribution network, it does not form part of the electrical installation. The electrical installation in practice in Thailand commences at the location of the PEA/MEA metering

The transformer will be located on the distribution network and will supply other properties as well as your own. The drawing itself is just that, it shows the relationship of the various components of the system to each other. It is a guide only.

[Negita43]

Hi everybody it’s me again I have now employed a Thai electrician and am about to start the installation of my house wiring.

Firstly the diagram sent me before says that all the mcbs should be elcb or rcbo BUT this will make the box very expensive.

There are available in Do home etc several makes of box with preinstalled mcbs and some have elcb or rcd or RCBO BEFORE the ordinary mCB

I have purchased one with an ELCB before the mcb’s (10 slots) BUT the electrician says the neutral bus bar will get hot and he doesn't like it.

In any case I think I prefer RCD to ELCB

He wants me to use a sneider or chang box BUT these a) are expensive and have special locators so you can only use their MCBs

I have shown him a box called SAFE T CUT (which has a RCBO before the other MCBs and this appears to have a sensitivity adjustment for the RCBO).

The electrician doesn't want this box. What concerns me is that he doesn’t want this box because he knows it will find him out if he doesn’t do a proper job!

Also he is saying that he wants the aircon to be wired before any elcb rcb etc because the surge when they switch on will cause them to trip.

BUT I had 4 aircon in my house in Spain with an RCD in front of all the MCB’s and it never tripped.

Any suggestions/helpful comments about consumer units etc anybody

Mike

PS found this on the inet about the differences between RCB RCBO ELCB – www.westernautomation.com/DemystifyingRCDs.pdf

[Crossy]

Get a new Sparks!

[Negita43]

Thanks Crossy but easier said than done Sparks comes with the builder - I lose the sparks I lose the builder!

Do you know about the safe T cut consumer unit??

Mike

[Crossy]

I would go with an ABB CU, DIN rail so you can configure how you like, split service with A/C and lights on the unprotected side water heaters and outlets on the protected side, easy peasy.

I do know the Safe-T-Cut CU, over priced for what it is.

[Negita43]

Thanks Crossy

Is ABB a brand?

Also I am used to RCD Do you think that would be OK instead of RCBO since as I understand it RCBO is RCD plus overload and I think I read somewhere that in all probability the main trip would go in the event of overload

Mike

[Negita43]

Sorry to ask another but what do you make of the sparks view that the neutral bus bar on the unit I have bought will get too hot (I think maybe its not copper but aluminium (as I understand it weight for weight Aluminium is a better conductor than copper) BUT whether its al or cu do you think that what he says is realistic

I ask this because the unit I have already (but I can change) has a din bar so it could be configured the same as you suggest

Mike

[Crossy]

Yes, ABB is a brand, but if you already have a unit with a DIN rail you're good to go.

I've not seen an Al neutral bar, not to say they don't exist (the ABB ones are a brass type material but tin plated). Cu is a better conductor than Al for the same area, weight for weight Al scores but has to be rather bigger in area. If you don't exceed the overall rating of your CU (should be marked on it) and it's a decent brand then you won't get overheating.

You can use an RCD between the two halves of a split service board, just ensure it's breaking capacity is the same as your incoming breaker.

[Negita43]

Thanks crossy you are a GEM

The CU I have is CCS - International electrical from Do Home (12 way) - I like to have spare capacity you can always not use but if you don't have enough then adding more is a BIG (hole in the wall) job

Mike