Electrics for new house - can it be explained in layman's terms?

[IMHO]

Some more suggestions, still off topic

Place your refrigerator on it's own breaker, so a fault somewhere else in the kitchen doesn't take it offline... or be prepared with an extension cord if a fault develops on the PK circuit

Delete the wall & door between the living area and kitchen, and replace it with a counter bar to open up the area more. Push the left wall of the kitchen out another 60cm, so additional cabinets can be installed without crowding the room. (this can be done with just mods to beams and walls only - same as Bath2).

[Sophon]

Some more suggestions, still off topic

Place your refrigerator on it's own breaker, so a fault somewhere else in the kitchen doesn't take it offline... or be prepared with an extension cord if a fault develops on the PK circuit

Delete the wall & door between the living area and kitchen, and replace it with a counter bar to open up the area more. Push the left wall of the kitchen out another 60cm, so additional cabinets can be installed without crowding the room. (this can be done with just mods to beams and walls only - same as Bath2).

Thanks for the suggestions.

I don't like open kitchens, so we will stick with the wall as it is. I don't really understand what you mean by pushing out the left wall (that's the outside wall), but it is too late to make modifications to the beams anyway. This is where we were a week ago:

Sophon

[Sophon]

I talked to our electrician today about the wiring.He is actually more like a foreman and have overseen electrical installations in builds in the middle east, he will do the work together with a guy from the local PEA office.

He has, what sound to me like some strange ideas. He wants to use black wire for live for the lights, but red wire for the power circuits. This is to make it easier to identify if a wire belongs to a light or power circuit. Also, he wants to use 1.5 mm² white wire for neutral, even for the power circuits where the live wire is 2.5 mm².

I can understand the reasoning behind the wire colours, but think we should stick to a standard. As I understand it, there is no Thai standard but most houses use the U.S. standard (black for live, white/grey for neutral and green for ground). With regards to using 1.5 mm² neutral wire on a circuit where the live wire is 2.5 mm², well that just sounds wrong to me.

It's a little bit of a delicate situation, as the guy is our future neighbour and has been a great help to us with the build so far. So we really don't want to offend him.

Sophon

Edited December 12, 2013 by Sophon

[Sophon]

While I remember.

We want to install double grounded power sockets everywhere, but the only type I can find are like this one:

However, some appliances (specifically many washing machines) have plugs where the wire come out at an 90 degree angle to the pins like this (pic borrowed from Crossy):

Because of the way the sockets are orientated, I don't think it will be possible to plug in two of these plugs in the socket, as one plug would be in the way of the wire coming out of the other one.

To me, it would be much more logical to have the ground pin pointing down, but I can't find any such sockets. Do I really have to install two separate power sockets if I want to have two washing machines side by side?

Sophon

[bankruatsteve]

I talked to our electrician today about the wiring.He is actually more like a foreman and have overseen electrical installations in builds in the middle east, he will do the work together with a guy from the local PEA office.

He has, what sound to me like some strange ideas. He wants to use black wire for live for the lights, but red wire for the power circuits. This is to make it easier to identify if a wire belongs to a light or power circuit. Also, he wants to use 1.5 mm² white wire for neutral, even for the power circuits where the live wire is 2.5 mm².

I can understand the reasoning behind the wire colours, but think we should stick to a standard. As I understand it, there is no Thai standard but most houses use the U.S. standard (black for live, white/grey for neutral and green for ground). With regards to using 1.5 mm² neutral wire on a circuit where the live wire is 2.5 mm², well that just sounds wrong to me.

It's a little bit of a delicate situation, as the guy is our future neighbour and has been a great help to us with the build so far. So we really don't want to offend him.

Sophon

The color doesn't really matter as long as it's consistent and follows convention - which would be the case you describe. BUT - it is not acceptable to use smaller neutral (there are exceptions but I don't think you have one).

[Crossy]

+1 steve, colour isn't really an issue (but he must stick to his 'code'), reduced neutral is absolutely not acceptable.

As to the outlets, I've not seen a double outlet in the orientation you suggest

Haco do a 3-pin plug with a cable that exits 90^o from the standard TIS plug (i.e. it hangs down when plugged into the regular orientation outlet), I cut the plugs off the washer and dryer and replaced them with the Haco ones. Two plugs in a double outlet, QED.

[Sophon]

Back again after some time to think and to work on the house build.

I have decided to accept black/red for live wires, but will obviously insist on neutral wires being the same size as live. I have taken some of your suggestions (much appreciated) to heart, and have decided for one circuit for everything downstairs which will run off a 20A breaker and 2.5 mm² live/neutral wires:

Upstairs I have split the kitchen outlets into two circuits and added a couple of down-lights (the GF was worried that there wouldn't be enough light over the kitchen counter):

The wires will go in to and out of the distribution board via 8 conduits running from the wall up into the attic:

As there is not room for as many conduits as I have circuits/breakers, some of the circuits will have to share space for the initial voyage from the distribution box to the attic. I was thinking of dividing the circuits like this:

Incoming conduits:

1. Ground wire from the ground rod
2. Live and neutral wires from the electric meter

I understand that to be "to code" the ground rod has to be 2.4 m long. But I have seen that Global (and others) sell rods of different diameter. Any particular diameter required for the ground rod to be acceptable to PEA and, of course, safe?

Outgoing conduits:

1. Lighting 1 (breaker 1), and
   Lighting 2 (breaker 2)
2. Downstairs (breaker 3)
3. Power 1 (breaker 4), and
   Power 2 (breaker 5)
4. Power 3 (breaker 6), and
   Power 4 (breaker 7)
5. A/C Bedroom 1 (breaker 8), and
   A/C Bedroom 2 (breaker 9)
6. Water heater Bathroom 1 (breaker 10), and
   Water heater Bathroom 2 (breaker 11)

I know that some of the conduits will be quite stuffed, but it's only for the first 1.5 meters, after that each circuit will split into their own conduit. I like the above division of circuits into conduits because it's logical (at least to me), but if need be I could re-arrange some of the circuits. Since I will be using 6 mm² wires for the water heaters, conduit 6 will no doubt be the most critical one. Should I instead pair up the circuits for A/C Bedroom 1 and Water heater Bathroom 2 (and likewise for Bedroom 2 and Bathroom 2)?

Another couple of questions:
With the planned division of circuits conduits 3 through 6 will all hold two circuits that each require ground wire. Should we run two ground wires in each conduit, or just one that will then be split in the attic when the circuits are led into separate conduits?

Talking of wires, I will need 16 mm² green wire (according to our electrician) leading from the ground rod and 6 mm² black/red (I'm not sure yet what our electricians code is for live wires for this) and white wire for the water heaters. I have seen these at Global but only in 100 m rolls, and I will need considerably less than that. Wires in these sizes are fairly expensive, so I would prefer not to have to buy more than I need. I must admit that I haven't asked at Global yet, so they may have something hidden away that I haven't been able to find yet.
Does anyone know of good resources for buying these kind of wires in shorter lengths than 100 m?

I am assuming that the ground wire leading to the ground rod doesn't have to be a special outdoor wire type, since it's basically designed to leak electricity into the ground (via the ground rod). It will be buried in the ground in the standard yellow conduits to give it some protection.
Am I wrong with this assumption?

I have read (looked at pictures) the instruction pamphlet that came with the Square D distribution board, and the connections seems fairly simple. But since I as mentioned have no prior knowledge/experience with electrical installation, I would like to confirm that my understanding is correct (don't worry, I won't try to install it myself ).

• Incoming cable from electric meter:
  Live wire goes to the "L" port of the RCBO
  Neutral wire goes to the Ground bar
• Neutral port of the RCBO is connected to the Ground bar
• Ground wire from the ground rod is also (not surprisingly) connected to the Ground bar
• Individual circuits:
  Live wire goes between the breaker for that circuit and the live port of light/power outlet/switch
  Neutral wire goes between the Neutral bar and the neutral port of light/power outlet. Each breaker has a corresponding neutral port in the Neutral bar.
  Ground wire goes between the ground bar and the ground port of the power outlet/A/C/Water heater

I also assume that where a light plus switch is connected to a circuit, the live wire runs to the switch first like this:

So have I got it all backwards, or is my understanding of the required connections basically correct? Please remember that I am a newbie at this and don't assume that I know something just because it's obvious to you, so any corrections however small are welcomed.

Sorry for the long post, but I have one last question (last for now, I make no promises about the future). The only wire connectors I can find at Global are these standard ones (the ones at Global are white):

When it is necessary to split off the main Live/Neutral/Ground cables of a circuit and run wires to a light or power outlet, it would seem more practical to use some kind of three-way splitter. Or do you just use the above connector and cram two wires into one end?

For anyone still awake, thank you for your attention and Merry Christmas. Any input is, as always, very much appreciated.

Sophon

Edited December 24, 2013 by Sophon

[Crossy]

Forget all those conduits, 2" square trunking will handle all the wires, look neater and be easier to fix when it's wrong.

Diameter of the ground rod shouldn't matter unless it's tiny.

Running the same size wire to the rod as your incomer is classical design, cannot go wrong.

Yes, that's how to wire your Safe-T-Cut.

Not elegant, but not unsafe to share grounds between circuits, make sure the ground is sized for the biggest circuit using it.

Most outlets sell wire loose by the metre, ask!

Yes, that's how to wire a light switch, often the neutral come to the switch box as well, handy if you have a ceiling fan or an outlet there.

Nothing wrong with two wires in one end of a choc-bloc, but your sparks will want to use wire-nuts, used correctly they are just fine.

[Sophon]

Thanks for your quick reply Crossy.

Forget all those conduits, 2" square trunking will handle all the wires, look neater and be easier to fix when it's wrong.

Sorry, I don't understand how it will look neater. I plan to recess both the distribution board and the conduits into the wall, and thought that having separate conduits (as far as possible) would give a better overview.

Not elegant, but not unsafe to share grounds between circuits, make sure the ground is sized for the biggest circuit using it.

Now I am getting confused. When the thread started I was told that the ground wire should be 1.5 mm², are you saying that some of the circuits (e.g. the water heaters) require a ground wire bigger than that?

If the norm is to run separate ground wires for each circuit, then I see no reason not to do that.

Nothing wrong with two wires in one end of a choc-bloc, but your sparks will want to use wire-nuts, used correctly they are just fine.

Wire-nuts, you mean like these?

I haven't seen those at Gobal, but then again I haven't known what to look for. I can see that they come in different sizes, and assume that the colour of the nut relates to the size not to the colour coding of the wires.

How do you use wire-nuts when attempting to split a circuit, do you put three wires into the nut and if so does that change the size of nut you need (compared to when you only connect two wires)?

Merry Christmas, I guess for you the big day is tomorrow (if you still celebrate).

Sophon

[bankruatsteve]

RE ground wire size: I will probably get safety shit for this, but I see no reason to go above 1mm2 for most ground wire applications. The concept of equal size is just conservative superfluous in my view and has no added protection.

[Crossy]

Ok, it's like this people.

There are ways of calculating the correct ground wire size for a given circuit. Most are too complex and unnecessary in our situations.

Rules of thumb:-

Make the ground the same size as the largest active conductor it serves - Belt and braces, could be expensive, guaranteed safe

Make the ground one size smaller than the active conductor - Fine in 99% of situations

I wouldn't go smaller than 1.5mm² on any circuit simply because small wire is easily damaged and, of course, you won't know the ground is broken until you need it.

Don't skimp on the cable to your rod, 10mm² minimum, 16mm² better, this wire could carry quite large currents if your system is MEN and there's a neutral fault between you and the transformer.

[Sophon]

Ok, it's like this people.

There are ways of calculating the correct ground wire size for a given circuit. Most are too complex and unnecessary in our situations.

Rules of thumb:-

Make the ground the same size as the largest active conductor it serves - Belt and braces, could be expensive, guaranteed safe

Make the ground one size smaller than the active conductor - Fine in 99% of situations

I wouldn't go smaller than 1.5mm² on any circuit simply because small wire is easily damaged and, of course, you won't know the ground is broken until you need it.

Don't skimp on the cable to your rod, 10mm² minimum, 16mm² better, this wire could carry quite large currents if your system is MEN and there's a neutral fault between you and the transformer.

So are you saying that I will need 4 mm² ground wires on my water heater circuits, which will have 6 mm² live/neutral wires?

Sophon

[Crossy]

So are you saying that I will need 4 mm² ground wires on my water heater circuits, which will have 6 mm² live/neutral wires?

As I said, it's a rule of thumb which will pretty well guarantee a safe installation, it doesn't hold good once we get past about 10mm² conductors.

Look at the ground sizes in this twin and earth from Bangkok Cable http://www.bangkokcable.com/catalog/BCC_CATALOG/VAFG2EN.HTML 6mm² has a 4mm² ground conductor.

What size breaker do you intend using on the 6mm², how long is the run from the board to the heater? With this information we can determine if 2.5mm² will be adequate as the ground.

[Sophon]

So are you saying that I will need 4 mm² ground wires on my water heater circuits, which will have 6 mm² live/neutral wires?

As I said, it's a rule of thumb which will pretty well guarantee a safe installation, it doesn't hold good once we get past about 10mm² conductors.

Look at the ground sizes in this twin and earth from Bangkok Cable http://www.bangkokcable.com/catalog/BCC_CATALOG/VAFG2EN.HTML 6mm² has a 4mm² ground conductor.

What size breaker do you intend using on the 6mm², how long is the run from the board to the heater? With this information we can determine if 2.5mm² will be adequate as the ground.

The breaker will be 32A. We will actually only be using 5,100 W water heaters, so 4 mm² wire and 25A breakers would be sufficient, but I have decided to go for the larger size, should we sometime in the future decide to upgrade the water heaters. The house is in Mae Tha in Lamphun which is slightly elevated, so it gets fairly cold in the winter.

Sophon

[Crossy]

So are you saying that I will need 4 mm² ground wires on my water heater circuits, which will have 6 mm² live/neutral wires?

As I said, it's a rule of thumb which will pretty well guarantee a safe installation, it doesn't hold good once we get past about 10mm² conductors.

Look at the ground sizes in this twin and earth from Bangkok Cable http://www.bangkokcable.com/catalog/BCC_CATALOG/VAFG2EN.HTML 6mm² has a 4mm² ground conductor.

What size breaker do you intend using on the 6mm², how long is the run from the board to the heater? With this information we can determine if 2.5mm² will be adequate as the ground.

The breaker will be 32A. We will actually only be using 5,100 W water heaters, so 4 mm² wire and 25A breakers would be sufficient, but I have decided to go for the larger size, should we sometime in the future decide to upgrade the water heaters. The house is in Mae Tha in Lamphun which is slightly elevated, so it gets fairly cold in the winter.

Approximately how long is the cable run? This is important in determining if you can use 2.5mm² for the ground.

[Sophon]

So are you saying that I will need 4 mm² ground wires on my water heater circuits, which will have 6 mm² live/neutral wires?

As I said, it's a rule of thumb which will pretty well guarantee a safe installation, it doesn't hold good once we get past about 10mm² conductors.

Look at the ground sizes in this twin and earth from Bangkok Cable http://www.bangkokcable.com/catalog/BCC_CATALOG/VAFG2EN.HTML 6mm² has a 4mm² ground conductor.

What size breaker do you intend using on the 6mm², how long is the run from the board to the heater? With this information we can determine if 2.5mm² will be adequate as the ground.

The breaker will be 32A. We will actually only be using 5,100 W water heaters, so 4 mm² wire and 25A breakers would be sufficient, but I have decided to go for the larger size, should we sometime in the future decide to upgrade the water heaters. The house is in Mae Tha in Lamphun which is slightly elevated, so it gets fairly cold in the winter.

Approximately how long is the cable run? This is important in determining if you can use 2.5mm² for the ground.

Sorry, I was on my way out the door and one of the dogs kept wanting attention and putting his head on the computer keyboard, so I forgot about your second question.

The cable run to one water heater will be approximately 6 meters and to the other approximately 15 meters.

I went to Global today and checked out the wire nuts. They seemed quite small and there was no indication on the bags about which wire size they were intended for. Any rule of thumb about wire size vs. colour of wire nut? Also, did you see my question about how to use wire nuts when splitting a circuit?

I hope you have had a pleasant Christmas day.

Sophon

[Crossy]

OK, let's take worst case conditions for your heater wiring (in reality with such short runs it's not actually worth calculating).

Assumptions:-

I'm going to ignore the supply impedance, it's only going to be an issue if our calculations have a marginal result.

The installation is MEN and has a N-E link in the incoming supply.

2.5mm² cable has a resistance of 7.4 ohms/km

6mm² cable has a resistance of 3.1 ohms/km

A 'C' curve breaker (most of them here are) will need about 10x its rated current in order to open in 0.4 seconds (a pretty global requirement).

We'll use the 15m run for our sums.

Let's take the final configuration of using a 40A breaker on your 6mm² (you've upgraded the heater to 9kW).

15m of 2.5mm² will be = 0.111 ohms

15m of 6mm² cable will be = 0.046 ohms

The 40A 'C' curve breaker will need 400A to guarantee opening in 0.4 s.

Total loop resistance in the event of a L-E fault at the far end of the run will be = 0.157 ohms (we should multiply by 1.2 to allow for resistance change as the cable heats up during the fault, so = 0.188 ohms) this equates to a current of about 1,100 Amps, more than enough to open the breaker in the required time.

In this case you can use 2.5mm² grounds to your water heaters.

To do it really rigorously look here http://www.tlc-direct.co.uk/Book/5.4.5.htm

Back home, the installer would actually measure the potential fault current at the heater to be sure that it ties up with the calculations.

To use wire nuts to tee off, simply prepare 3 cut ends (2 from your main, one for the dropper), insert into the wire nut, tighten (use pliers or a nut spinner of the right size). You can get 4 or 5 ends in a nut if there's room.

The nut should be a firm push over the prepared ends (don't twist them first), just select the nut that is the best fit.

[bankruatsteve]

RE wire nuts in LOS: most are crap - OK they still work but you have to make SURE connection - twist until very tight - make sure nothing pulls out - and then tie-wrap the wire bundle. Although it varies, use yellow for 2-3 2.5mm, red for more. Use orange for 2 1.5mm. Use small orange/grey for like the light fittings. The (what is it?) WAGO connectors see to be the best although I have struggled with what's easily available connectors otherwise and HOPE they don't fall out.

[Sophon]

Thanks for the info Steve. You say:

use yellow for 2-3 2.5mm, red for more.
Use orange for 2 1.5mm.
Use small orange/grey for like the light fittings.

What's the difference between the second and third line (we will use 1.5 mm² for the lights), and what would you use for 3 1.5 mm² wires (also orange I assume)?

Sophon

[Sophon]

OK, let's take worst case conditions for your heater wiring (in reality with such short runs it's not actually worth calculating).

Assumptions:-

I'm going to ignore the supply impedance, it's only going to be an issue if our calculations have a marginal result.

The installation is MEN and has a N-E link in the incoming supply.

2.5mm² cable has a resistance of 7.4 ohms/km

6mm² cable has a resistance of 3.1 ohms/km

A 'C' curve breaker (most of them here are) will need about 10x its rated current in order to open in 0.4 seconds (a pretty global requirement).

We'll use the 15m run for our sums.

Let's take the final configuration of using a 40A breaker on your 6mm² (you've upgraded the heater to 9kW).

15m of 2.5mm² will be = 0.111 ohms

15m of 6mm² cable will be = 0.046 ohms

The 40A 'C' curve breaker will need 400A to guarantee opening in 0.4 s.

Total loop resistance in the event of a L-E fault at the far end of the run will be = 0.157 ohms (we should multiply by 1.2 to allow for resistance change as the cable heats up during the fault, so = 0.188 ohms) this equates to a current of about 1,100 Amps, more than enough to open the breaker in the required time.

In this case you can use 2.5mm² grounds to your water heaters.

To do it really rigorously look here http://www.tlc-direct.co.uk/Book/5.4.5.htm

Back home, the installer would actually measure the potential fault current at the heater to be sure that it ties up with the calculations.

To use wire nuts to tee off, simply prepare 3 cut ends (2 from your main, one for the dropper), insert into the wire nut, tighten (use pliers or a nut spinner of the right size). You can get 4 or 5 ends in a nut if there's room.

The nut should be a firm push over the prepared ends (don't twist them first), just select the nut that is the best fit.

Thanks Crossy, I gave up trying to follow your calculations and skipped to the part I understood :

In this case you can use 2.5mm² grounds to your water heaters.

So I will use 2.5 mm² ground for the water heaters.

Also thanks for your info about the wire nuts. I have looked on the internet and some say twist the wires first, others say don't. I will go with your recommendation and see if that's how our "sparky" is used to doing it.

Sophon

[bankruatsteve]

Thanks for the info Steve. You say:

use yellow for 2-3 2.5mm, red for more.

Use orange for 2 1.5mm.

Use small orange/grey for like the light fittings.

What's the difference between the second and third line (we will use 1.5 mm² for the lights), and what would you use for 3 1.5 mm² wires (also orange I assume)?

Sophon

In the states, there are "rules" for color and wire combinations. But here in LOS, I find variations in the nuts. My guess is that yellow would be good for 3 1.5mm2. The important part is that you end up with all wires connected and secured. The nuts I used in the states would do that. Here, sometimes they don't - so I would go with twisting them together first - but sometimes that makes the nut difficult to apply. Tywrap the wires if they are not in a box - which they should be at connection points but for lighting I've done that.

Edit: I would add that the Thai sparks seem to like putting a VERY solid twist on the wires and then applying a huge amount of tape. And, that's probably good or even better than using nuts.

Edited December 26, 2013 by bankruatsteve

[wayned]

The wires should always be twisted first to insure a good mechanical connection no mater where you are. The main purpose of the twist on connectors and tape is insulation and an added mechanical "clamp".

[Crossy]

The wires should always be twisted first to insure a good mechanical connection no mater where you are. The main purpose of the twist on connectors and tape is insulation and an added mechanical "clamp".

That's what I always thought, and was correct with the old "Screwit" connectors.

If you look at the manufacturer's sites for modern wire nuts they now recommend NOT twisting the wires, confusing innit?

Personally, when there are more than 3 wires (and I don't have big Wago terminals to hand) a couple of twists to hold the wires together before winding the nut on with a nut-driver makes life easier.

EDIT -

Leviton advocate at least partial twisting first http://www.youtube.com/watch?v=32z6Q8--fEM

Ideal say no need (but don't prohibit) http://s114.photobucket.com/user/mdshunk/media/73binstructions.jpg.html

[Sophon]

Happy New Year everyone.

New question related to earlier discussions. I have adopted a suggestion from Crossy and decided to run everything on the ground floor off a main circuit with 2.5 mm² wires and a 20A breaker. I assume that droppers for switches and lights can still be with 1.5 mm² wires (droppers for electric outlets will, of course, be using 2.5 mm² ground/neutral). Is that a correct assumption, and will connecting wires of different thickness with a wire nut be problematic?

Sophon

[bankruatsteve]

Happy New Year everyone.

New question related to earlier discussions. I have adopted a suggestion from Crossy and decided to run everything on the ground floor off a main circuit with 2.5 mm² wires and a 20A breaker. I assume that droppers for switches and lights can still be with 1.5 mm² wires (droppers for electric outlets will, of course, be using 2.5 mm² ground/neutral). Is that a correct assumption, and will connecting wires of different thickness with a wire nut be problematic?

Sophon

It would not be proper to run 1.5mm2 on a 20a breaker - but if it's just for lights I don't think a problem. Yes, you can combine different size wires in a wire nut - the IMPORTANT thing is that they are well connected. Twisting first is a sure way to do that. Tywrap the bundle helps to secure

[Crossy]

Agree Steve, 1.5mm² is good for 15A, you're unlikely to get anywhere near that on a lighting circuit unless it's Wembley you're lighting. The important part is that short circuit protection is there and with a 20A breaker I anticipate no issues on that front. So whilst it would not pass muster to some country's codes there's not a serious issue.

To twist or not to twist, that is the question

[Sophon]

OK, so running 1.5 mm² whilst not proper would not really be a problem. On the other hand it wouldn't really be a problem either for me to use 2.5 mm² wires for the lighting circuits, so if it was your house would that be what you would do?

Sophon

[Crossy]

To be honest and pragmatic, in this situation I'd run 2.5

Means you could do the Thai thing and put an outlet in a spare way of the light switch.

[bankruatsteve]

And, for me it would be no problem to run on 1.5mm2. There is just no way that would be a problem for lighting circuit.

[Crossy]

@Sophon.

Either way is just fine

up2u