Minimal Electricity Setup

[canopy]

I would like to tap into the grid to open land that will have a meter soon. For now I just want a single 220V outlet. What minimally would be needed to do this the right way? I want to run cable/conduit underground to the outlet that will be 100M away from the meter because in the future plan to upgrade electrical to serve a house so want to do good groundwork that is applicable towards that end. I am looking for a parts list of what to get minimally for an outlet. Getting proper installation specs would also be great.

[Crossy]

Depends upon your load.

For your initial connection 100m of 4mm² on a 5/15 meter will do the job just fine. Ensure you have a 20A MCB and a 30mA RCD protecting your outlet. You should be able to find an enclosure that will house everything for a neat job (if it's not in a building said enclosure will need to be weatherproof).

Use a local ground rod for the earth on your 3-pin outlet.

Now, for your earthworks and final installation we need a bit more information, how big a home (and therefore power supply) are you intending? will you be needing 3-phase? Both these questions will need you to to do a maximum demand calculation to get a meaningful answer.

Obviously the answers to the above will determine what sort of cable and (possibly) underground ducting you'll need to install.

I would be tempted to bung the 4mm on temporary poles (or in typically Thai fashion nailed to trees) to get the supply on-site then you can work on your house plans and start construction.

[canopy]

You should be able to find an enclosure that will house everything for a neat job (if it's not in a building said enclosure will need to be weatherproof)

Is there a good place in Bangkok for finding good quality items including these? And how is HomePro in this regard?

how big a home (and therefore power supply) are you intending? will you be needing 3-phase?

3-phase not needed. Max load padded with future margins: 40 amps to serve 20kWh per day.

I would be tempted to bung the 4mm on temporary poles to get the supply on-site then you can work on your house plans and start construction.

Yes tempting, will consider that too but right now prefer to run appropriate cable for a full house from the beginning so I don't have to do things twice.

[Crossy]

OK then, with a 15/45 meter you'll be needing 25mm² copper or 35mm² aluminium for a volt drop of less than 5% between the supply pole and your distribution board.

If the budget runs to 35mm² copper or 50mm² aluminium you'll get a better volt drop performance. Whether you need this really depends upon how far your tap off point at the road is from the transformer and what the off-load voltage is.

Personally I'd use the bigger Aluminium cable as it's significantly cheaper, but it's important to use the correct terminations to avoid the risk of fires.

You could use a directly-buriable cable (easier) or regular cable in a suitable buried conduit (cheaper), ask your contractor about conduit size as he'll be the one putting the cable in it. Either 'should' be at least 500mm (the deeper the better) down and under a warning tape.

[canopy]

it's important to use the correct terminations to avoid the risk of fires

What does correct terminations involve? I've gone through your very good site but haven't run across this topic.

ask your contractor about conduit size as he'll be the one putting the cable in it.

If only...kind of a rant but I do not have trust in contractors following specifications. Just looking around my rental place power arrives by way of a crude tree branch and the house goes into a brown out when the electric water heater is used. I'll just stop there to keep it short. The way things are done here I do not care for. I want everything to meet or exceed code.

[Crossy]

Some useful information for those considering using Aluminium (Aluminum) cables:-

http://ecmweb.com/construction/electric_timeless_tips_terminating/

http://www.ecasa.co.za/Press/2007/CoppervsAluminiumCon.pdf

And some examples of bi-metallic terminals to use Al cables in connectors intended for Copper:-

http://www.indiamart.com/company/1813802/products.html (sorry they're in Mumbai).

The big issue in Thailand will be lack of knowledge of the requirement for the correct terminals and anti-corrosion jointing compound.

[kloghead]

HI canopy--I went down this road about 10 days ago. Check out the thread: http://www.thaivisa....c-cable-prices/

Listen to Crossy--he knows what he's talking about

I ended up with 35 mm2 aluminum cables x 215 meters long clamped into 16 mm2 copper cables x 20 meters long (at the PEA meter/knife switch end). The result was 227.8 V at the business end.

I joined the copper/aluminum cables with two bog-standard clamps (about 25 baht each) and doubled over the 16 mm2 copper cores to make them fit snugly into the grooves of the clamps. Dipped them in some 'Skotch-Kote' I had laying around, wrapped the connection with 'Skotch 23' stretch tape then finished the join with plain old electricians tape.

I did the connections myself and I ain't no sparky--so I'm sure you can also.

Hope this helps...

Edited December 4, 2010 by kloghead

[canopy]

Good info all. Plan to go with copper then and one of the things on the outlet will be surveillance system with battery backup and motion detection that automatically sends an SMS picture. Here is how the parts list is shaping up:

(1) get a "tee yoo" for the property from the PYB to bring to the PEA

(2) 15/45 meter from PEA

(3) 63A main MCB

(4) 30A outlet MCB

(5) 30ma RCD

(6) weatherproof panel

(7) 16mm2 copper wire to run underground 50M from meter to panel

(8) conduit for above (tbd)

(9) two 200mm2 solid copper ground rods x 2.5M long (US spec)

(10) 13mm2 bare copper wire to run from copper rods to panel

(11) 3.3mm2 UF copper wire to run underground from panel to outlet

(12) conduit for above (tbd)

(13) warning tape

(14) common tools (already have)

(15) finally, the outlet

But still some questions:

Q1: Does the meter need to be at the edge of the property on a utility pole like everyone else does? In the US it is considered better practice to have the meter on the house back to back with the panel.

Q2: what is the appropriate conduit for meter to panel in this case?

Q3: what is the appropriate conduit for panel to outlet in this case?

Q4: where to find SOLID copper acorn clamps or similar to connect the ground wire to the ground rod?

Q5: what are the names for the wires I am interested so I can identify them in the store / people there know what I am talking about?

Q6: where are good places to buy this type stuff in BKK?

Q7: is a 30ma RCD appropriate for a whole house with everything connected to it?

Q8: any other additions, comments? Please fire away.

[kloghead]

Check out this place for supplies/prices: http://www.klangfaifa.com/

The PEA will put your meter where all the others are unless you make alternate arrangements ($$$). One inch PE pipe will be OK for your 16 mm2 cables. Have you considered bundling a phone line with the electrics?

Maybe someone else can help you with question # 7...

[electau]

Max demand 45A

Main switch /MCB 63A.

Power, socket outlet RCBO 20A/30ma. 2.5sqmm cable. all socket outlets to be earthed.

Earth electrodes minimum 12.7mm copper clad steel. 1.8M.

Earth conductors. main earth minimum 4sqmm, PEA/MEA may require 10sqmm.

Earth conductors insulated conductor green /yellow or green.

Location of metering is the responsibility of the PEA/MEA and is generally at or near the property line.

32mm UPVC conduit minmum for enclosure of 2 single insulated and sheathed 16sqmm copper cables.

Telephone and comms. cabling must not be enclosed in the same conduit as power cables and must be segregated in separate conduits or ducting.

You could split the RCD circuits over two RCD units or have one RCBO for each final subcircuit.

[Crossy]

I'll endorse what electau says above with one minor adjustment.

The usual stuff used in Thailand for underground electrical conduit is black HDPE with a red or orange tracer to indicate it's electrical.

You can find various ways of arranging your consumer unit / distribution board here http://www.crossy.co.uk/wiring/Consumer.html

[canopy]

Great. I think what I will do is use a basic main MCB and then use an RCBO for each circuit. That way if in the future I want an unprotected circuit it can easily be accommodated.

One curiosity; I noticed they sell HDPE elbows. Are these a good idea or is the conduit flexible enough on its own to contour a decent 90 degree bend up the trench? The reason I ask is it seems preferable to have continuous conduit rather than have underground breaks with elbows.

[Crossy]

I'd stick to using one piece, make sure you keep the bend radius as large as possible to avoid issues getting the cable in.

Don't forget to bung up the ends (spray PU foam works well) to stop the local fauna setting up home in your thoughtfully provided burrow

[canopy]

Earth electrodes minimum 12.7mm copper clad steel. 1.8M.

Earth conductors insulated conductor green /yellow or green.

Earth conductors. main earth minimum 4sqmm, PEA/MEA may require 10sqmm.

Grounding--I really appreciate those specs. To me the art of grounding is an extremely important subject. My observation is grounding is skipped altogether in Thailand with 2 prong sockets the norm. To go on a little tangent, I insisted a grounded outlet be added to the house I am renting now and found it interesting they chose a RED colored wire for ground that dangles down the wall where they sank a rod directly below it inside the house. The wire is fastened by way of a steel bolt (not even stainless) which is an incompatible metal with copper. The ground wire is sandwiched between 2 metal nuts on the bolt and does NOT directly contact the ground rod! Just saying this to emphasize again I am really counting on you guys to help me get this right because it doesn't seem like I have the possibility of finding better guidance than what you are supplying. Here are a few observations from my shopping:

The heaviest green wire I have found is only 6sqmm and it is multi-strand at that. One store even steered me towards an even smaller size as being "all you need for that". That's strange because even a hypothetical 10sqmm which I could not find would not meet code in the US. I plan to select 16sqmm and that means it will have to be black color and putting some wraps of green electrical tape on the ends seems the best I can do.

Each store I visited only sells electric cable where the ground wire is a smaller gauge than the other 2 wires. There seems no way around this issue.

Electrical shops only offer small copper plated rods which would not meet code in the US for many reasons and it seems would not even pass Thailand's own codes either. However, I found big 16mm diameter solid copper rods--at plumbing shops of all places.

One other curiosity; I asked various shops about warning tape for trenches and best I got was some laughs. One claimed Thailand doesn't have that sort of thing.

[Crossy]

Each store I visited only sells electric cable where the ground wire is a smaller gauge than the other 2 wires. There seems no way around this issue.

Certainly the norm here and now in the UK (and probably elsewhere too). Absolutely no problem provided the loop impedance is low enough to open the protective device within the required 30ms or so. If you have an RCD / RCBO even a relatively poor ground will open the breaker in the event of a L-E fault (no, that's not an excuse for installing crap grounds).

In the bad old days the norm of making the ground conductor the same size as the largest active line was a solid belt-and-braces rule that always resulted in a satisfactory loop impedance. Now with increased copper prices the cable manufacturers are minimising the size of a non-active conductor. This increases the requirement for proper installation testing (including loop impedance checks) which, of course, never happen here (do I own the only 16th Edition installation tester in Thailand?).

[bankruatsteve]

Just to say... in the USA (at least 30 years ago) the bundlled ground wire was bare copper and probably no larger than 1mm2 no matter what size the prime cable. Or maybe my memory bad. But, I think providing the ground connection aint the same requirement as the load connection, yah?

And here I have yet to find anywhere that sells cable including the ground. For me, I bought the 1mm2 green wire and routed along with the primary cable - which was annoying but I hope effective.

Edited December 21, 2010 by bankruatsteve

[canopy]

During install, the 25mm² cable did not fit into the meter contacts. The tech then cut strands off until they did. Was that a good solution?

[Crossy]

During install, the 25mm² cable did not fit into the meter contacts. The tech then cut strands off until they did. Was that a good solution?

It was a Thai solution

What he should have done was crimp a short length of 16mm on to the end of the 25mm (called a pigtail).

Whilst not ideal, so long as only a few strands were removed there should be no issue.

[canopy]

That doesn't sound as bad as I thought; they broke off 1 of the 7 strands. When I objected the other option they gave me is to get a 30 amp meter which has bigger contacts. Couple questions on this:

If I use the bigger meter are there any reasons for or against increasing the main breaker size? According to the calculator there will be too much voltage drop at higher loads due to the long distance involved.

There is going to be a breaker installed on the power pole after the meter for safety so I have a way to shutoff power to the long underground cable run. Should it be equal in size to the main breaker such as 63amp? Or should it be sized differently?

Last, I noticed the return on the power pole is wired to ground (these are brand new power lines). Does that mean it would be appropriate to implement the MEN/PME link on the panel?

[Crossy]

OK to answer your questions in the wrong order

If you are going to install a means of killing the power near the meter I would use a 100A isolator rather than a breaker. An isolator is pretty much just a big switch, it has no overload protection. This means that it's usually cheaper and there will be no problem with discrimination in the event of an overload, you can guarantee that a breaker on the pole will only trip when it's pissing down. Even the rather scary looking Chang brand knife switches will do the job perfectly if they're in a nice weatherproof enclosure.

If you can't get an isolator use a 100A breaker, that will ensure that the 63A in the house will open first, again avoiding getting you wet. You can use a short length of 16mm to link to the meter and avoid having to snip strands of your 25mm.

Using 100A units will ensure that the 25mm will fit in the connectors without difficulty.

If your load has not increased there's no point in putting a bigger breaker in the house even if you get the larger meter (again no point if you're not overloading the 15/45).

If your neutral is grounded at the pole you are reasonably assured that MEN/PME is implemented and a N-E link in your distribution board is a recommended addition. DO ENSURE that L and N are the correct way round on your incoming supply before inserting the link though. A voltmeter between the points you intend to link will do the job (look for 0V).

[electau]

The size of the protective earth conductor is based on the size of the phase (active) conductor.

The main earth conductor must be a minimum of 4 sqmm.

The minimum size of an individual protective earth conductor is 2.5sqmm. The exception is where the PE conductor is laid up with other current carrying conductors in the same sheath, eg 1.0 and 1.5sqmm.

The earth conductor is approx 1/3 of the size of the phase or active conductor.

Source AS3000. MEN system.

Correct size of earth conductors is important as the impedance must be low enough to operate the protective device in the event of an earth fault within the stipulated time limits, for an MCB this is 0.4secs.

Under AS3000/2007 Impedance tests are only required on socket outlet circuits that are not protected by an RCD.

Earthing tests are mandatory.

[canopy]

The PEA made a mistake and cut the wires running down the pole a little too short such that they couldn't reach the bottom of the weather proof box where the breaker resides. Their solution to this predicament was to drill a hole in the side of the weatherproof box and run the wires in the side. See picture. Now when it rains water runs down the wires, into the box, and all over the breaker. Any suggestion on a good resolution to this?

[Crossy]

Bloody typical

A few ideas:-

Move the box up 30cm?

Splodge silicon around the cable entry hole.

Tell them to do it right

[doglover]

If you move the enclosure up 30 cm it will be ideal for cable entry but create other hazards for any work required in the future. Of course very little work will be required in the future but i can picture somone standing on a empty flipped over paint can to get high enough or a taller person having there face directly in the 'line of fire' should the worst case scenario happen.

If you stick with that side entry I would purchase a 'strain relief' connector (if such a thing is available) and hole saw the hole to an appropriate size (which will be tricky seeing as there is a hole in place already). A strain relief connector consist of a fitting that has a few pieces. (try googling for a pic)

1. the main body of the connector which will attach to your enclosure via a the locknut
2. a rubber grommet that is sandwiched between the main body and a cap that when tightened will apply pressure to the rubber grommet and create an appropriate seal around your cable for the weather and for anyone who may give it a tug.

......then. I can see for your pic that if you just stip the ends of the wire and terminate you will have enough slack to create a bit of a 'drip loop' just outside the strain relief connector and rain will not be directed into the fitting.

....or you could just use silicone .

EDIT - ensure you pick a size of strain relief just big enough for the cable to slide through unresisted for correct sizing. it will clamp down properly after you snug it up.

Edited March 5, 2011 by doglover

[Crossy]

Agree DL, the problem will be getting a suitable gland, you'll likely be able to get on that fits the cable (one for each wire) but it's unlikely that it will fit the existing hole, time for a large blind grommet (which is something I've failed to find here).

With a drip loop you should actually be able to stop most of the rain getting in even without sealing the hole (I'm assuming that you're entering the breaker from above)

[doglover]

Agree DL, the problem will be getting a suitable gland, you'll likely be able to get on that fits the cable (one for each wire) but it's unlikely that it will fit the existing hole, time for a large blind grommet (which is something I've failed to find here).

With a drip loop you should actually be able to stop most of the rain getting in even without sealing the hole (I'm assuming that you're entering the breaker from above)

I guess I should have downloaded his picture for a bigger image. The wire that comes down my pole is equivalent to a massive speaker wire. For termination a slit is made between the two conductors and they are pulled apart until sufficient individual conductor length is available for termination purposes. So mine could be stuck into one strain relief. With two connectors it's gonna get a little tight it looks like. But if you manage to find these (most likely elusive) strain relief connectors I forgot to mention they are usually not weatherproof. You will need some kind of rubber washer to be sandwiched between the exterior of your enclosure and where the s.r. connector will contact it to have a truly professsional seal. But TiT and I agree with Crossy that with a drip loop it would be 'good enough'.

[doglover]

I have a question (not a challenge) that relates to this subject I asked you a question in 'domestic electrical wiring' thread Crossy to do with an incorrectly assumed (by me) maxed out transformer. Without mentioning any sizes you stated that the single phase from PEA passing by my house would be 16mm2. Do they use a generalized wiring size sheme? Did I miss something?

I think I must have missed something as they use aluminum I believe and that would be quite small. Especially if 25mm2 copper is being tapped off of this for the cable drop to his 100A breaker (i understand it is just an expensive switch). I have never spliced bigger wires onto smaller feed wires to deal with volt drop. But I do understand that from the point of the splice it will help curb further losses more effectively than a similar sized wire spliced onto the smaller feed wires.

Ok, so he feeds into his 100A breaker with 25mm2 but then has to wire the load side of the breaker to the line side of the 15(45)A meter with 16mm2 and then carries on to the house from the load side of the meter with 25mm2 (missing a strand for the first 1/2 inch). Is it even possible to properly calculate the voltage drop with that weak link in place? Could the PEA not swap out the lugs to a bigger size on that meter? And if they did how about the internal wiring or busses of a 15(45)A meter, would this be the new weak link? I would think the internals only support the 45A max for how they are sized. So for no weak links isn't the only solution an upsized meter that has internal wiring equivalent to 25mm2?

*I did direct this at Crossy as he's familiar with my scenario in the other thread. But a reply from anyone is welcome*

Edited March 5, 2011 by doglover