Running Mains Electric Cable

[Isan Farang]

Just had the meter installed, i do not wish the cable to high so my two options are place the cable underground or run it along the wall around around 1ft above the ground.

 

I went to checkout the 15amp cable today and it comes in 100m rolls which is perfect, when i asked about the pipe to run the cable through they told me they have never been asked this before.

 

Just checking if i go under the ground level do i need special cable and pipe, and how about if i go above the ground level, is the cable and pipe the same.

[Crossy]

With a 15/45 meter you need cable capable of 50A or so, that would mean a minimum of 10mm², PEA may insist on 16mm² before they will pass the installation for a permanent supply, check with them.

 

If the run is long you may need larger cable to avoid volt-drop issues.

 

Running cable underground or at low level will need an insulated and sheathed cable, the official designation of this is is NYY.

 

The normal stuff used to run to the house is THW, but this isn't suitable for low level (it's not sheathed) or underground so is usually mounted on poles with insulators.

 

EDIT PEA may not accept even NYY running at low level. Check with them or consult your contractor.

 

NYY whilst it is suitable for direct burial it's not armoured so ideally it needs to go in a conduit, or you could use an armoured cable (SWA).

[bankruatsteve]

Check your plans with the PEA before you do anything.  Most PEA will not allow underground if crossing public road, etc.  Once on your property you can do what you want.  The distance from the meter to your CU will also determine size of wire required.

 

There is no "pipe" for overhead but underground is usually run in conduit as additional protection to the NYY cable.

[Crossy]

Also. If this is your first meter you will have a "construction supply", you can get away with almost anything on the load side of the meter but you will be billed 8 Baht per unit.

 

To get a permanent supply and pay 4 Baht per unit you will need to pass a PEA inspection. Whilst it's not anything like as rigorous as it would be in the west they still do take safety seriously.

 

This document is worth a lookGroundwire Mk2 book-Manual.pdf as is this pinned thread 

 

[Isan Farang]

1 minute ago, Crossy said:

With a 15/45 meter you need cable capable of 50A or so, that would mean a minimum of 10mm², PEA may insist on 16mm² before they will pass the installation for a permanent supply, check with them.

 

If the run is long you may need larger cable to avoid volt-drop issues.

 

Running cable underground or at low level will need an insulated and sheathed cable, the official designation of this is is NYY.

 

The normal stuff used to run to the house is THW, but this isn't suitable for low level (it's not sheathed) or underground so is usually mounted on poles with insulators.

Thanks for the info, i just want to do some ground work before i talk with the electric man as they will just tell me to go with the over head normal method.

 

The total cable run is around 70m.

 

I am about to build a base and cover for the water storage tank's and feed pump. Would it be possible to run this cable to some sort of control box that i will mount in this room and then when the garage and house is built i can go from there to the main box.

[Crossy]

For 70m you are definitely going to need 16mm² cable if you go copper, aluminium cable is a lot cheaper but you'll need 25mm² minimum, 35mm² would be better. Do note that aluminium isn't allowed underground.

 

There's no reason why you shouldn't build a pump house, garage, whatever and run the incoming supply there, if you put your main breaker in that room you have a handy way of isolating your entire supply.

 

 

[Isan Farang]

14 minutes ago, bankruatsteve said:

Check your plans with the PEA before you do anything.  Most PEA will not allow underground if crossing public road, etc.  Once on your property you can do what you want.  The distance from the meter to your CU will also determine size of wire required.

 

There is no "pipe" for overhead but underground is usually run in conduit as additional protection to the NYY cable.

No issues on the cable run as the post for the meter is next to my wall, can you give me a link to the conduit

[Fruit Trader]

15/45 feed off our pole to Aunts shack. 16mm NYY cable inside 50 meters of 50mm HDP conduit below ground. The cable passes under a public road shared by only three properties but as already mentioned might not be allowed in some areas. 

 

 

 

[bankruatsteve]

1 minute ago, Isan Farang said:

No issues on the cable run as the post for the meter is next to my wall, can you give me a link to the conduit

All the "Home" places carry.  

[Crossy]

Also. How far is your meter from the village transformer?

 

Although the supply is nominally 220V +-10% that can vary significantly, if you are more than, say, 100m from the transformer it may be wise to go even bigger on your own cable to keep the voltage within sensible limits.

 

To give you something to compare to. We are on a 15/45 single-phase, typical village setup.

 

About 160m (cable size unknown) from transformer to meter then 50m of 16mm² copper between the meter and our board.

 

Measured supply impedance is about 0.5 ohms at the board (I've never checked at the meter but 100m [out and back] of 16mm² copper is about 0.115 ohms). That's 1V of drop for every 2A of load, so at least in theory, full load of 45A would drop us to 197.5V.

 

Our problem is that in the evenings the "off load" (in reality about 4A) voltage is already down to 200V and can only head downwards from there.

[Isan Farang]

4 minutes ago, Crossy said:

Also. How far is your meter from the village transformer?

 

Although the supply is nominally 220V +-10% that can vary significantly, if you are more than, say, 100m from the transformer it may be wise to go even bigger on your own cable to keep the voltage within sensible limits.

 

To give you something to compare to. We are on a 15/45 single-phase, typical village setup.

 

About 160m from transformer to meter then 50m of 16mm2 copper between the meter and our board.

 

Measured supply impedance is about 0.5 ohms at the board (I've never checked at the meter but 100m [out and back] of 16mm2 copper is about 0.115 ohms). That's 1V of drop for every 2A of load, so at least in theory, full load of 45A would drop us to 197.5V.

 

Our problem is that in the evenings the "off load" (in reality about 4A) voltage is already down to 200V and can only head downwards from there.

Regarding the transformer distance i need to check on this one, i am new to this area in Chiang Rai so trying to gather some advice here.

 

My knowledge on electric is very limited so thus the various questions before i talk with the electric man. In Ubon i have 3 phase overhead cable, so on this one i wish to change the layout.

[Crossy]

6 minutes ago, Isan Farang said:

In Ubon i have 3 phase overhead cable, so on this one i wish to change the layout.

 

It's worth doing a quick and dirty load calculation for your new home. If it's going to need 3-phase best to get the infrastructure in now rather than try to retro-fit later.

 

Give us an idea what your major loads will be and we can do a guesstimate for you ????

 

[Isan Farang]

2 minutes ago, Crossy said:

 

It's worth doing a quick and dirty load calculation for your new home. If it's going to need 3-phase best to get the infrastructure in now rather than try to retro-fit later.

 

Give us an idea what your major loads will be and we can do a guesstimate for you ????

 

This one is only a small house with max 2 AC, i used to work in the Oilfield so now my new schedule is 1 month Ubon and 1 month Chiang Rai 

 

Before i start building next year i want to get the water and electric all sorted out. Its looking like i will ask a price from the PEA as if some papers is required then very easy when they complete. 

 

[bankruatsteve]

43 minutes ago, Isan Farang said:

This one is only a small house with max 2 AC, i used to work in the Oilfield so now my new schedule is 1 month Ubon and 1 month Chiang Rai 

 

Before i start building next year i want to get the water and electric all sorted out. Its looking like i will ask a price from the PEA as if some papers is required then very easy when they complete. 

 

Water heaters?  Water pumps?  Ovens?  Swimming pool?

[eyecatcher]

It may have been touched upon above but the standard cheap aluminium core nains cable must be kept above 2.4m high or buried.

if you want a cable running on a boundary wall then it must be replaced with copper core.

[Isan Farang]

59 minutes ago, bankruatsteve said:

Water heaters?  Water pumps?  Ovens?  Swimming pool?

Water Heater ? - Hot water shower

Water Pump - Mitsu as in picture

Oven & Swimming Pool - not required

[Crossy]

I think you'll be OK on a 15/45 single-phase provided you can keep the volt drop under control.

 

Most of us have similar supples and rather larger homes. Just don't run your 8kW (I would go for 6kW) water heater (or is that two), both aircons and then do some welding.

 

We have taken our 15/45 past 63A on occasion (briefly), it has not entered low earth orbit.

 

[Isan Farang]

16 minutes ago, eyecatcher said:

It may have been touched upon above but the standard cheap aluminium core nains cable must be kept above 2.4m high or buried.

if you want a cable running on a boundary wall then it must be replaced with copper core.

I have left a space between the land fill and slot in section, so i will check if i can go under the final fill level, this run is around 46m and then i have to go along the back wall (half way) around 18m

[Sophon]

18 hours ago, Crossy said:

For 70m you are definitely going to need 16mm² cable if you go copper, aluminium cable is a lot cheaper but you'll need 25mm² minimum, 35mm² would be better. Do note that aluminium isn't allowed underground.

 

There's no reason why you shouldn't build a pump house, garage, whatever and run the incoming supply there, if you put your main breaker in that room you have a handy way of isolating your entire supply.

 

 

 

15 hours ago, eyecatcher said:

It may have been touched upon above but the standard cheap aluminium core nains cable must be kept above 2.4m high or buried.

if you want a cable running on a boundary wall then it must be replaced with copper core.

So, which is it, can aluminium be buried or not?

 

Sophon

[Crossy]

8 minutes ago, Sophon said:

So, which is it, can aluminium be buried or not?

 

Our local PEA say aluminium cable can absolutely NOT be buried in a domestic situation, things may be different for industrial mind.

 

Also Bangkok Cable do not appear to do an aluminium version of NYY. The only LV aluminium cables available are;-

• NAY which is specified as a PEA drop cable.
• THW-A & AWV which are both LV overhead.

 

[eyecatcher]

19 minutes ago, Sophon said:

 

So, which is it, can aluminium be buried or not?

 

Sophon

Both....oh, seems I am wrong, my spark did say they can be buried if they are ducted. 

but if this is a no no.....sorry

[bankruatsteve]

17 minutes ago, eyecatcher said:

Both....oh, seems I am wrong, my spark did say they can be buried if they are ducted. 

but if this is a no no.....sorry

NYY cable is available for Al but maybe not in Thailand. (?)

[Crossy]

Just now, bankruatsteve said:

NYY cable is available for Al but maybe not in Thailand. (?)

 

It's not available from the Thai sources I've checked, admittedly not all of them.

 

[Isan Farang]

On ‎5‎/‎13‎/‎2019 at 10:31 AM, Crossy said:

 

It's not available from the Thai sources I've checked, admittedly not all of them.

 

Just a quick update on my cable run, the electric man has now completed the under ground cable run and connected to the meter, I also placed all the PVC water pipe before the CPAC was poured

[RichCor]

On 5/10/2020 at 9:08 AM, Isan Farang said:

Just a quick update on my cable run, the electric man has now completed the under ground cable run and connected to the meter, I also placed all the PVC water pipe before the CPAC was poured

 

 

 

That "residential" CU seem rather open to the elements.

[Crossy]

9 minutes ago, RichCor said:

That "residential" CU seem rather open to the elements.

 

Indeed, I would have given it an outer box.

 

In reality it will probably be just fine, it's under a roof and protected from blown rain by the fence.

[sometimewoodworker]

10 minutes ago, Crossy said:

 

Indeed, I would have given it an outer box.

 

In reality it will probably be just fine, it's under a roof and protected from blown rain by the fence.

Humm I don’t think that you have seen the horizontal gale force  blown rain we get in this area. Also that fence isn’t close, probably about 2 metres back.

 

Unless there’s significant protection that is not visible, or going to be put in later, I’d put money on the insides of all those boxes getting somewhere between damp and soaking wet during the rainy season.

[RichCor]

I'm concerned about the fail safes of any electrical near water, especially if it's mains electrical delivered straight from the pole with the meter being the only source of potential cut off from whatever the pole connection can deliver.

 

If this is a 'sub' protected by an upstream RCD then it's less cringe-worthy.

 

 

[Crossy]

Given IP rating is IP4X - zero moisture protection. Anything more than light blown rain may be an issue.

 

I thought it was an all-plastic box, but it seems not.

 

It does need a outer box.

 

[Isan Farang]

31 minutes ago, RichCor said:

That "residential" CU seem rather open to the elements.

I am having canvas tarps made to measure at a shop in Ubon to cover all 4 sides and will return to CR and have them fitted. I just recently completed all the tank pipe work so now ready to cover everything