Size of cable to run110m

[Chao Lao Beach]

I once saw a caculaor to work this out. I presume I will need 75mm alloy. 15A

Any tips?

Anyone know price of rolles of this these days ?

[Crossy]

The Doncaster Cables calculator is here http://www.doncastercables.com/technical-help/

15A at 110m comes out at 6mm² Copper for a 5% drop. Rule of thumb is to go one size bigger for Al, so 10mm².

BUT!

What is on the far end of the run, a water pump, your house? Either would need an adjustment to the load current used to calculate the cable size.

[Chao Lao Beach]

Crossy, this is from the meter box to the house. I was not clear about that, sorry.

[Crossy]

Ah ok then.

If you have a 15/45 meter (the most common) then you're looking at 25mm² copper or 35mm² Al.

On a 30/100 meter you'll be heading towards 35mm² copper or 50mm² Al.

If there's no issue with funds I would go even bigger on the Al, it's not expensive and the extra volt or two may be the difference between your water pump starting and it not.

Talk to your contractor about what size PEA will connect to their meter, you may need to splice copper pigtails onto the Al cable.

[cheeryble]

Crossy I tried to look up your answer to me a year ago about a run approaching 400m.

We are at last getting on with the utilities, and wife informed me late last night she is going out with sis to buy epic cable and concrete and metal posts and fittings to support the cable.

She has arranged with a guy who works for the PEA to fit i apparently.

He says, and the guy before him says, use 25mm cable (meaning Aluminium presumably).

On looking at the table the table you kindly supplied it does indeed say 25mm....but presuming that's copper and you speak of 35mm Aluminium.

To be clear I am trying to stick to a real budget here and it is not a big house with air in every room, it is two rooms with a total area of 50m2.

However it will have two water heaters for example.

Now I don't mind a hint of undersupply if things.....like water heater and toaster ......happen to get switched on exactly the same time once in a blue moon and the water doesn't get quite so warm.

But things like the pump need to be functional.

Can I do with 25mm as he says?

(I might add the missus got on with this independently and we don't want a loss of face thing for her or the guy if possible.)

ps The 25mm is costed at 10400 baht on her list

Thanks Crossy

[Crossy]

Volt drop is going to be the killer.

400m of 25mm² copper will drop about 5% at only 15A, 25mm² Al will be rather more drop. Barely acceptable, particularly if you have a decent water pump and aircon to start.

You will need a massive 95mm² at 45A (for a 15/45 meter), a more manageable 35mm² copper (50mm² Al) will be dropping 5% at 20A.

[cheeryble]

Thanks Crossy

I've got a problem here.

The wife has organised this and I don't want to take away her confidence or make her lose face.

After being told by the PEA guy that 25mm is the size she has a spoken to the supplier about larger sizes after I put my fat mouth into it.

He has told her he only once ever gave anyone over 25mm and they brought it back because the electrician complained.

I am loathe to stick my foot into it more. I might almost prefer to rebuy in the event we have a problem.

BTW the meter arrived apparently (it's a new meter from the sister's house from which we will be sharing the supply presumably using our own meter to share the bill fairly.)

Next time i'm there I shall check but before it was the minimum type and this is now the more up to amperage of supply.

What would that likely be?

ps may just possibly have one aircon eventually.

[bankruatsteve]

Don't worry about it. 25mm2 Al probably can carry all you need even with the volt drop. My experience in the hinterland is that the PEA supplied voltage is higher than nominal (like mine is usually 230 or so) to compensate for some of those long runs. (?)

[cheeryble]

Don't worry about it. 25mm2 Al probably can carry all you need even with the volt drop. My experience in the hinterland is that the PEA supplied voltage is higher than nominal (like mine is usually 230 or so) to compensate for some of those long runs. (?)

An intentional overvoltage?

Now there's a concept (and let's hope so)

Course it raises prospects of litigation as Somjit could claim his wattage used is x% more than it should be and is a plot and the PEA better pay him back plus a buffalo.

[Crossy]

Minimum meter is a 5/15 - enough for a Thai shed. Most common meter is a 15/45 good for 50A or so (11kW) enough for most homes.

If you're sharing a meter do take care you don't overload it on a regular basis, they are very robust but lose accuracy if pushed to the limit.

Grid voltage does vary over time, ours gets to about 235V about 6% high (+10% is 242V) in the dead of night down to 210V about 6% low (-10% is 198V) in the early evening when the resort next door is active. Of course, your needs are likely going to be greatest when everyone else's are and the voltage is already low

To be honest (and for a quiet life) go with what Wifey has ordered, at only 11 Grand it's not an expensive item and if it proves too small when you add the A/C you can double up with another run of the same cable on the same poles so it's not going to be wasted.

[cheeryble]

Thanks for that good information and the fair compromise Crossy.

I have learned how important it is dealing with SWMBO in at least slightly Thai fashion. Their good attitude is surely more important than mere material perfection.

I guess the main drawers of current would be water heaters,.i have thought of a solid fuel stove, a little one, but likely I'll be using some sort of air heater in the very chilly northern cold season. Luckily with the heaters I'm guessing they would simply give a reduced thermal output if temporarily overloaded which is no big deal. I guess the thing with aircon is they tend to stay on sometimes semi permanently so are a contstant load. All the other stuff in the house and pumps etc are just occasional.

[RichCor]

And don't forget the option of adding an AVR (Automatic Voltage Regulator).

AVR discussion in past ThaiVisa threads:

Electricity meter size and low voltage?

Started by ilikethai, 2014-04-10 13:24 -- 10 replies

Voltage drop solved

Started by Apache704, 2013-10-01 03:28 -- 60 replies

"Can someone explain how these AVR's work when the grid goes low?"...

Crossy, Back to Basics post # 35

[cheeryble]

Will look that up later Richcor thanks.

Good news is we have some action......sister's meter (we will draw from it) is upgraded, concrete pylons (dirt track) and metal poles (hillside) are delivered and sitting in their holes ready for concrete maybe tonight.

When we have hooked up the guys maybe can use the leccy to pump out the well as they dig deeper. (hopefully it will fill up fast enough for them to pump it out!)

Out of interest we sometime will need to put a sub-meter down line from sister's to read and work out our share of the bill.

Am I right in thinking that meters (if not supplied by PEA) are quite cheap? Ballpark price?

[anterian]

My meter is a 5/15. I have 3 aircons, at any given time 2 are running, a fridge, electric kettle, microwave, industrial sewing machine, 400w PC, fans, lights etc. Electronics workshop (sig gen, bench power supply, soldering iron etc). The meter often spins like a gyroscope but never have any problems with volts drop.

[Crossy]

My meter is a 5/15. I have 3 aircons, at any given time 2 are running, a fridge, electric kettle, microwave, industrial sewing machine, 400w PC, fans, lights etc. Electronics workshop (sig gen, bench power supply, soldering iron etc). The meter often spins like a gyroscope but never have any problems with volts drop.

What is the measured voltage at your meter, distribution board?

You are likely overloading your poor little meter, although they're very robust they become inaccurate when overloaded and you can bet they don't read low.

What rating is your incoming breaker?