Domestic Electrical Queries

[nobber9999]

Having had various "Thai Electricians" in to do a variety of electrical work I have finally decided to check it and re-run it as I am given to understand how it should be properly run. They all seem not to have any idea what a ring main is as I have ended up with various bodge jobs up in my attic with no circuit returning to the CU. To avoid future problems I have decided to leave the circuits as radials just to avoid future confusion.

However, having read numerous articles regarding the length or area that a single radial circuit can safely service slightly confuses me. Having a length of wire XX meters long is nice and simple but these figures seem a long way different from the articles which refer to "area". I talk about a length of wire from the CU, across the roof space then down through the conduit and back up again and so on. This in quite simple terms would use far in excess of the "length of wire" calculations and would probably only manage a few wall sockets unless the conduit run was horizontal between sockets. It would seem that I will need 6mm solid wire for such a long run to avoid voltage loss rather than 4mm which seems to be used for a maximum 20 meter run.

This leads to my next question. Having laid the mains to the first junction box, can I just run a single live, neutral and earth down to the socket with no return or do I have to run the main from the junction box, down to the socket and then back up again and onto the next socket?

Finally, the CU is a split load which is great for keeping essentials on when the RCBO trips but I do have a query regarding the earth connection. This is run using 10mm twisted copper wire from the CU then down to a 3m copper earth rod. The Thai electricians forgot to run the earth to a large ornamental pond which powers the filter, air pump and fountain and also provides a spare connection for any out door tools. To solve the earth problem they sunk a separate copper rod into the ground and connected it to the sockets. Will this still allow the RCBO to trip in the event of a leakage as the earth is not bonded to the main earth rod? Secondly, my swimming pool was wired in a similar fashion. The electricians ran the power from a dedicated MCB in the main CU to a second CU in the pump house which has no RCBO and yet again they ran the earth to a new earth rod which they sunk close to the pump house. For some reason the did not use the earth on the main CU and once again the rod is not bonded to the main earth rod. Can anyone give me some advice on this?

By the way....... I have no intention of playing with live wires or wiring the CU myself. All I want is to know that what lies across my attic is neat and tidy, uses proper junction boxes with screw connectors (not twisted wires) and is of ample size to service the equipment it has to supply without dimming all the lights and reducing voltage more that the normal acceptable limits.

[Crossy]

Domestic ring mains with fused plugs do not exist in Thailand, in fact they are a peculiarly British thing. Leave everything on radials.

Have a look here http://www.crossy.co.uk/wiring/ it should answer most of your issues

Wire your outlets with 2.5mm 3 core cable (it probably has a 1.5mm ground core) or 2.5mm twin with a separate 1.5mm ground if you can't get 3 core. Protect each radial with a 20A breaker. In a domestic situation you're unlikely to run into cable length issues but there's a volt drop calculator on the page noted above.

I would limit each radial to 7 double outlets although there is no actual maximum number permitted, we've got it split by room with two circuits to the kitchen where the high current appliances live.

An ELCB/RCCB/RCD/RCBO/GFI/Saf-T-Cut does not require a ground to function correctly, your seperate pond and pool ground rods will protect you perfectly well

Junction boxes are also unknown and unobtainable, the best you'll do are twist-on 'wire nuts'. These are perfectly acceptable provided they are correctly fitted and taped. If you really want UK type JBs you can get them in Malaysia where MK have distributors

I would install an RCBO in your pump house if it's not running from the protected side of your split-load CU. If you have pool lighting I would strongly recommend you replace any mains fittings with low voltage units.

[nobber9999]

[Great help... thanks.

Just out of interest, Haico have a reasonable collection of electrical bits and pieces including 3 pin slimline vertical plugs and connection boxes with grommets. Do Home and Home Pro are a couple of places that hold some of their stock.

Once again... cheers.....

[Crossy]

Just out of interest, Haico have a reasonable collection of electrical bits and pieces including 3 pin slimline vertical plugs and connection boxes with grommets. Do Home and Home Pro are a couple of places that hold some of their stock.

Interesting, IME HomePro have always been sadly lacking in 3 pole plugs (outlets no problem) and cable.

My local mom-and-pop electrical emporium (it's such an Aladdins Cave it can't just be called a shop) has a far better selection although all the plugs are very agricultural in design

I'll look out for the Haico stuff

[mgjackson69]

Crossy,

Great web site...I browsed through it and learned a lot already. At some point I want to rewire our house, adding a proper CU (in USA we call it a breaker panel or distribution panel usually, but anyway) and getting rid of the twisted and taped connections up above the suspended ceiling. I am sure that your site will be a lot of help when I tackle that project.

I made an observation recently that is a curiousity to me...I guess you can probably solve the riddle.

We were over at a friend's house a few evenings ago. I made a trip into the house. Most of the lights were out, but I noticed that all of the flourescents were glowing slightly...is this a faulty job of wiring or something else? What do you think?

[Crossy]

We were over at a friend's house a few evenings ago. I made a trip into the house. Most of the lights were out, but I noticed that all of the flourescents were glowing slightly...is this a faulty job of wiring or something else? What do you think?

Almost certainly caused by the switches being in the neutral, or possibly (and considerably more worring) an overall live-neutral swap. If you have a neon screwdriver verify that what you think is the live in the CU really IS live.

If you don't have a neon screwdriver go and buy one (the type you put your finger on the end of), the best 100Baht you can spend if you intend going anywhere near a Thai electrical installation.

[dotcom]

nobber. Where do you live?

I have always heard the term "Load Center" in Thailand.

[mgjackson69]

We were over at a friend's house a few evenings ago. I made a trip into the house. Most of the lights were out, but I noticed that all of the flourescents were glowing slightly...is this a faulty job of wiring or something else? What do you think?

Almost certainly caused by the switches being in the neutral, or possibly (and considerably more worring) an overall live-neutral swap. If you have a neon screwdriver verify that what you think is the live in the CU really IS live.

If you don't have a neon screwdriver go and buy one (the type you put your finger on the end of), the best 100Baht you can spend if you intend going anywhere near a Thai electrical installation.

I have one of those in the toolbox...I will take it with me next time we go over there.

Thanks