Jump to content

Cable size meter to building 72M


Recommended Posts

7 minutes ago, regedit said:

You mean run a cable from the roof steel to the rod (so 2 cables will finally be attached to the rod) ? 5 of the earths will pass through the roof space so adding one more attached to the steel down to the control room will be doable.

 

What size cable for CU to rod and roof steel to rod ? Mains supply will be on 4x32mm.

 

Yeah, our roof steel actually tests better (by a factor of 4) than the 2.5m rod.

 

From the main CU to the rod, 16mm2 minimum, if you've got some 32 spare that's your stuff, but for all grounds, basically the bigger the better.

Link to post
Share on other sites
  • Replies 41
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

Thai cable is not the same quality so it's very hard to calculate the real thickness.   And also those transformers mounted on poles, they explode regularly or they start melting and drippin

From the OP, 10 rooms, each with it's own meter. I think it safe to assume each room is a longer term rental.    As such, all or most AC likely at the same time, and all or most hot showers

How will the rooms be configured?  AC?  Hot shower?  Kitchen(ette)?  30A per room seems like maximum demand potential that might be very unlikely to occur.  Reality might be 50A for the entire buildin

Posted Images

Reading all this has got me thinking.

Where in Thailand can you buy 2 core +earth cable for domestic wiring.  When my house (in Phayao) was built, I had to bring a drum of 2+ earth from UK as every electrical shop I asked at was "why you want 3 wires.? Only use 2 in Thailand."  

My experience of Thai electricians has been that earths wires are not considered to be important, more like a waste of money.  All vry keen to sell me a 'safety cut' (ELCB) but cannot understand why an earth wire is needed.

My observation of  (overhead) wiring in my village is that we have 3 phases and a earth, which is also the neutral or return.  Any experts here care to comment on this.  I am not an electrician, but just try to use common sense when coping with Thai wiring:-

1.  Make sure that the live is switched, not the neutral.

2.  Make sure that all screw connections are done up tightly; do not rely on wires twisted together.

3.  The correct wire for the connection is the one that will carry the current used, not the smallest that will work for 5 mins. (until the electrician is of the site.)

 

Link to post
Share on other sites
42 minutes ago, Robin said:

Where in Thailand can you buy 2 core +earth cable for domestic wiring. 

Well it’s really difficult but how about; Global House, DoHome, Thai Watsadu, HomeHub, HomePro and every electrical supplier. I’ve seen it in all of them and bought from some of them.

 

  • Like 1
Link to post
Share on other sites
46 minutes ago, Robin said:

My observation of  (overhead) wiring in my village is that we have 3 phases and a earth, which is also the neutral or return.

It will be the neutral, in a lot of places it is earthed at about every 3 pole as in MEN but you need to check as it may not be.

Link to post
Share on other sites

@Robin

 

Common sense is indeed the way to go.

 

If that cable from the UK is the regular T&E with the reduced size, bare earth core then it technically does not meet the Thai regulations which require a full size, insulated earth core, it's perfectly safe of course (I hope it's not wired as a "ring main" on a 32A breaker). The equivalent here is VAF-G (the G designates it has the earth core). This is the stuff you'd use for outlets 

https://www.homepro.co.th/p/1018377 

 

Untitled.jpg

 

It did used to be as common as hen's teeth but is now readily available as is 3-core flex, often in Black, White, Brown (I use the brown for earth).

 

Thailand local supplies are 3-phase, 4 wire, 220V Phase-Neutral (230V in Bangkok) supposedly TN-C-S with MEN (look for the earthed neutral on the supply poles). A MEN link between a local earth rod and neutral is required in your consumer unit. Many get alarmed at this link, but much of the UK is the same apart from the link being hidden in the service head.

 

A handy PEA document Groundwire Mk2 book-Manual.pdf 

 

And the important diagram with translations, note the routing of the incoming neutral via the earth bar to implement the MEN link.

 

Groundwire Mk2 book-Manual-1 diagram.jpg

 

 

 

 

Link to post
Share on other sites
28 minutes ago, Yellowtail said:

Is what looks like wire-rope strung across the top the ground/earth?

The high voltage lines only have three and a ground, correct?

 

The "wire rope" on top of the HV poles is lightning protection, it's not a service conductor although it is earthed. 

HV lines are 3-phases only plus that lightning protection.

 

The 4 LV lines usually have the neutral at the top and it's bare (and also looks like wire rope), the phases themselves are insulated.

 

The neutral is usually earthed every 3rd pole or so making it MEN (multiple earthed neutral) and there's also a link between the neutral and earth (and your local rod) inside your consumer unit, making the service TN-C-S with MEN.

 

Wiki has a good discussion of earthing systems 

https://en.wikipedia.org/wiki/Earthing_system 

Thailand is generally TN-C-S with MEN or TT.

 

 

Link to post
Share on other sites
On 11/20/2020 at 5:17 PM, Crossy said:

 

Yeah, our roof steel actually tests better (by a factor of 4) than the 2.5m rod.

 

From the main CU to the rod, 16mm2 minimum, if you've got some 32 spare that's your stuff, but for all grounds, basically the bigger the better.

Would it be wrong to go instead from the roof steel to the earth busbar in the big distribution board, and then have only 1 cable from the busbar to the earth rod?

Link to post
Share on other sites
6 minutes ago, regedit said:

Would it be wrong to go instead from the roof steel to the earth busbar in the big distribution board, and then have only 1 cable from the busbar to the earth rod?

 

My only reservation would be if your roof took a lightning hit the current would all be going via your ground bar.

  • Thanks 1
Link to post
Share on other sites
20 minutes ago, Crossy said:

 

My only reservation would be if your roof took a lightning hit the current would all be going via your ground bar.

 

Lightning in Thailand?

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.


×
×
  • Create New...