Socket Wiring - Running Cable

[painless]

Hi All,

I just need to clarify something. I have to run the wiring externally, as in not behind

the wall. I would have thought that it would be best to make a join above the ceiling

and run a length of cable down to each wall socket. However I find references to joints made at the socket.

eg

http://www.ultimatehandyman.co.uk/replacin...aged_socket.htm

This would require a double length of cable, one down and one up.

Can one of you gents clarify this for me please. Thanks

[longball53098]

I don't know British wiring standards but in the US if installing multiple outlets on the same line from the Consumer Panel individual breaker I would run one length of cable from the panel to the box above the ceiling and then drop the individual runs to each socket on the wall(s) and make one splice in that box. If you are installing more than a few outlets the splice may get unmanageable though so you may have to install more than one J box to handle the drops to the outlets. No big deal though justmake good splices that are all capped with twist on caps.

[mgjackson69]

I have seen it done both ways here.

Joins at the socket seem to be common where the house has an open ceiling.

I agree with you...why run the extra cable?

[gdhm]

I would like to ask a question about running cable.

In the UL I am used to seeing 2 or 3 wire (N.L,G) in one cable. I am aware Thailand seldom has 3 wire cable only two so if a ground wire is required it is run separately along side the 2 wire cable.

My question. In Khon Kaen I see builders (and my builder's electrician) is doing the same thing namely the Neutral, Live and Ground wire is individual and not all 2 or 3 enclosed in an additional protective PVC outer casing.

All my wiring is run through yellow plastic conduit (My request for some protection) but I wish to confirm whether separate wires in their individual PVC coating but NOT all enclosed together in an outer PVC coating are OK and do not change their characteristic regarding over heating or load tolerances.

It is obviously done to save money on the outer casing. The electrician seems to be following correct guildlines for thicker wire for higher loading.

Thanks

Dave

Edited August 16, 2008 by gdhm

[painless]

My question. In Khon Kaen I see builders (and my builder's electrician) is doing the same thing namely the Neutral, Live and Ground wire is individual and not all 2 or 3 enclosed in an additional protective PVC outer casing.

Dave

I just bought some insulated 3 core from Global House in Khon Kaen. I don't think you would save much money, if any by running the ground separately. Perhaps the electrician has never bothered to buy any.

[dotcom]

That 3 core cable is a new idea. Not every shop will stock it. The bigger & better shops will. 2 x 2.5 + 1 x 1.5.

GDHM. Those white cables are known as double insulated. They are fine for indoor use.

If you wish to run that inside conduit even better.

Most of the time however we run individual strands of single insulated cable inside the conduits. I would say if you are burying wire inside walls ceilings etc then use conduit. On wall apps can be the double insulated runs.

To the OP.

It is not nescessary to make a run from a socket back to the main. I would look to use junctioin boxes to make a tidy installation.

Always try & wire in a modular fashion so if a run should be damaged or stops working you can replace just the bad section. I will try & get pictures from my house.

[gdhm]

That 3 core cable is a new idea. Not every shop will stock it. The bigger & better shops will. 2 x 2.5 + 1 x 1.5.

GDHM. Those white cables are known as double insulated. They are fine for indoor use.

If you wish to run that inside conduit even better.

Most of the time however we run individual strands of single insulated cable inside the conduits. I would say if you are burying wire inside walls ceilings etc then use conduit. On wall apps can be the double insulated runs.

To the OP.

It is not necessary to make a run from a socket back to the main. I would look to use junction boxes to make a tidy installation.

Always try & wire in a modular fashion so if a run should be damaged or stops working you can replace just the bad section. I will try & get pictures from my house.

Thanks Dorcom and Painless.

Painless that is good to know for th future but this time around the Builder and electrician have already progressed way beyond changing the wire (unless somebody said to me what they have done is dangerous.

Dotcom you have said what I hoped and believed (without being certain). MY suspicions that Double insulated cables (thanks for helping me out with the correct terminology (I was struggling ) were more to do with neatness and added protection/insulation than load bearing reasons.

You mention "On wall apps can be the double insulated runs".

You say can but do they need to be IF the electrician uses the correct thickness of wiring for 20A and 32A appliances (6 Kw and 8 Kw heater heaters and oven/hotplate or is the plastic conduit still an adequate double insulator. I will try to suggest to the electrician he get double insulated for these (but workmen do not always take kindly to changes in their normal procedures (especially when they actually do seem to know what they are doing (this electrician is the first I have personally encountered in Khon Kaen who seems to be doing all the things I have found out on ThaiVisa AND he seems to be thorough and proactive and not only reactive to my input -Thank goodness.

I know the UK and advanced electrical safety countries would consider plastic conduit insufficient and metal covering of wires appropriate. Regretfully TIT on this matter. I insisted upon plastic conduit as a minimum knowing it will provide more protection than single insulated or double insulated wire alone cemented into a wall, and that it would allow easier repair/removal if wiring if problems occur later.

Of course a drill head will go clean through plastic conduit. I am pleased to say the electrician and builder have faithfully gone directly up or down from ALL switches and sockets and not horizontally or diagonally anywhere. (OK two are slightly on the angle but neither outside the left/right sides on the double plug sockets below them SO I know provided any future drilling is outside the width of each switch or plug socket there is no way I will hit an electrical cable (famous last words ).

Dotcom ther electician has used junction boxes as I can see them screwed to walls (above the level of the ceiling plasterboards_ - so that's good.

Water pipes are slightly less reliably straight, but outlets give a good idea of where they are and are not (in MOST cases )

Thanks Both.

Dave

Edited August 16, 2008 by gdhm

[Crossy]

The advice above is good, so long as the joints use wire nuts and are protected in junction boxes you'll be fine.

The UK uses ring mains (unheard of in Thailand) which use a bigger breaker (32A) but the same 2.5mm² cable rated at 20A, which is why you must make all wiring from socket to socket and back to the distribution board to maintain the integrity of the ring. Radial wiring as in Thailand uses a 20A breaker on each run so there is no need for a ring.

It sounds like your chap has got a good handle on safe installations

Edited August 16, 2008 by Crossy

[dotcom]

GDHM. I strongly advise running 4 mm wires + ground (which can be 1.5 mm) for water heaters kitchen stoves air cons etc.

The 2.5 is normally for sockets that see TV's fans microwaves & the occasional hair dryer.

The 4 mm runs should have their own breakers in the load center. One for each air con & 1 for each water heater.

My air cons are on 6 mm wires which I chose to give me some added safety factor.

[gdhm]

GDHM. I strongly advise running 4 mm wires + ground (which can be 1.5 mm) for water heaters kitchen stoves air cons etc.

The 2.5 is normally for sockets that see TV's fans microwaves & the occasional hair dryer.

The 4 mm runs should have their own breakers in the load center. One for each air con & 1 for each water heater.

My air cons are on 6 mm wires which I chose to give me some added safety factor.

Thanks Dotcom ,

On another thread Crossy recommended the same as you and even suggested 10mm for the 8kW water Heater (as it was over 7kW)

I have instructed my electrician on these already (and he seemed to agree with the ratings).

I am watching closely (not that I can tell which is which, BUT I can tell when wires are much thicker or not than those used in socket wiring and lighting. So far the socket wiring is thicker than the lighting (which is what I'd expect (probably 1.5mm and 2.5mm) SO I expect 6mm and 10mm to be over double thickness and treble.

He has suggested he is going to use around 32 separate breakers (fuses) in the main box which is what I estimated (based upon Crossy's advice) with a few in reserve (once again we shall see I am watching carefully (and he knows I am)

Regards

Dave

Thanks. All supporting info adds confidence

[Crossy]

I am watching closely (not that I can tell which is which, BUT I can tell when wires are much thicker or not than those used in socket wiring and lighting. So far the socket wiring is thicker than the lighting (which is what I'd expect (probably 1.5mm and 2.5mm) SO I expect 6mm and 10mm to be over double thickness and treble.

It's not quite that easy, remember the cross-sectional area is equal to "pi r²" so it's not just twice the area = twice the diameter.

To go from area to diameter you need "2 x root(area/pi)"

To make your job slightly easier :-

Area ....... Diameter ..... Nearest AWG

(mm2) .... (mm) ........... equivalent

1.5 .......... 1.4 ............. 15

2.5 .......... 1.8 ............. 13

4 ............. 2.3 ............. 11

6 ............. 2.8 ............. 12

10 ........... 3.5 ............. 7

Remember these figures are the size of the copper with the insulation removed.

Note that 2.5mm² is not actually much bigger in diameter than 1.5mm² easy enough to tell when you see then side by side though. Use your vernier caliper, micrometer or a sample of known size to compare.

Edited August 18, 2008 by Crossy

[dotcom]

As promised.

This picture is what I call "On the wall" the electrician will install these "clips" about every 10 cm (4 inches). Notice it is double insulated wire.

This happens to be in my carport.

Edited August 18, 2008 by dotcom

[dotcom]

Here is the promised picture. This is in the dining room. It is a junction between the kitchen (where the load center is) living room dining room & wire going up to the staircase light.

I chiseled out a hole in the concrete to accept a double wall socket box. I made all my connections - wire nuts & tape. Then I located a "blank" cover & 4 screws. I pained it with latex house paint. Unless you know it's there you don't see it.

Hope this helps.

[dotcom]

Lastly I recently installed a junction box for my water pump. Went up to the hardware store where they sell these boxes. You do your splice & then screw the cover on. Keeps the rain off of it.

[Crossy]

Lastly I recently installed a junction box for my water pump. Went up to the hardware store where they sell these boxes. You do your splice & then screw the cover on. Keeps the rain off of it.

Your joints look well taped but are there wire nuts in there or just twisted joints? I'd use a 'choc-bloc' connector as in my experience wire nuts 'aint too smart joining solid to stranded cable (like the one that is coming from your pump).

It's a good idea to put a tie-wrap / zip-tie on the cable on the inside of the box so it can't be accidentally pulled out of the box exposing the splice to the elements.

Of course, the ideal solution would be a waterproof outlet if you can get one.

Is the pump double insulated or earthed?

Edited August 19, 2008 by Crossy

[gdhm]

I am watching closely (not that I can tell which is which, BUT I can tell when wires are much thicker or not than those used in socket wiring and lighting. So far the socket wiring is thicker than the lighting (which is what I'd expect (probably 1.5mm and 2.5mm) SO I expect 6mm and 10mm to be over double thickness and treble.

It's not quite that easy, remember the cross-sectional area is equal to "pi r²" so it's not just twice the area = twice the diameter.

To go from area to diameter you need "2 x root(area/pi)"

To make your job slightly easier :-

Area ....... Diameter ..... Nearest AWG

(mm2) .... (mm) ........... equivalent

1.5 .......... 1.4 ............. 15

2.5 .......... 1.8 ............. 13

4 ............. 2.3 ............. 11

6 ............. 2.8 ............. 12

10 ........... 3.5 ............. 7

Remember these figures are the size of the copper with the insulation removed.

Note that 2.5mm² is not actually much bigger in diameter than 1.5mm² easy enough to tell when you see then side by side though. Use your vernier caliper, micrometer or a sample of known size to compare.

Many Many thanks Crossy ,

I will keep this info in my DIY files.

I assumed INCORECTLY that the measurements (10mm2 for example) were the diameter of the double insulated Cable. I admittedly, was unsure how that logic applied to flat cables where width is greater than height.

Now thanks to you I understand my error and know what to look out for. As they say a little knowledge can be a dangerous thing.

Must admit being British I had to look up AWG (American Wiring Gauge). Its interesting that the thicker the wire the lower the AWG. Learn something every day

Kindest regards and thanks again for all the advice you have given me concerning Wiring in this thread and another. I am using your information "like a Bible"

Dave

[Crossy]

Must admit being British I had to look up AWG (American Wiring Gauge). Its interesting that the thicker the wire the lower the AWG. Learn something every day

555. I'm a Brit. too. I included the AWG so our American friends wouldn't feel left out (and it was already in the table I nicked), actually it's handy to have if you're looking at American wiring websites.

Standard Wire Gauge (SWG) the imperial version of AWG also goes 'backwards' and remember the BA (British Association) thread sizes, 0BA was biggest, 8BA was tiny and 10BA was almost invisible

[dotcom]

Thanks Crossy. All good points. You are 100% right.

The water pump has only 2 wires (supplied with Thai style flat pins) non polarity. At the mo those are just twisted. Good eye. Will get more pics. Yeah I am a big fan of soldering stranded wires.

The pump controller is made of plastic so I guess you would call that double insulated.

Pictures of my new pump in another thread here. Very quiet powerful & cheap. It senses if there is suction present & can't run "dry". Smart controller. Has idiot lights too.

[Crossy]

The water pump has only 2 wires (supplied with Thai style flat pins) non polarity. At the mo those are just twisted. Good eye. Will get more pics. Yeah I am a big fan of soldering stranded wires.

Me too, wrap the stranded round the solid (so that the result looks like a continuous wire) and solder, cover with heat-shrink tubing and then an overall heat-shrink to cover the lot. If you can get the heat-shrink with an adhesive inner layer (not seen it here yet) the result will be pretty weatherproof, although I don't think I'd put it in direct rain.

One thing to watch when soldering stranded. The solder tends to wick up inside the insulation so any heat-shrink needs to go a good 20mm up the insulation to give support, otherwise any flexing will break the wire inside the insulation (at the point the solder wicking ends), invisible to the eye and an absolute bind to locate until it starts arcing

I have a few crimp splices with a heatshrink outer. Crimp in the normal way then use your heat gun (lighter) to shrink the insulation and make a strong weatherproof join. They came from RS in Hongkong, RS have a branch in BKK (in the CMIC / K-Tower on Asoke) so I expect I'll be able to get some more (not cheap though).

If your pump has a metal frame, I'd be tempted to earth it anyway, one of the small ground rods will give that extra peace-of-mind

By the way, I just noticed that you've got two holes in the box, but the wires are joined before passing through them. Oops (been there, have the T shirt)

Edited August 19, 2008 by Crossy

[dotcom]

Ha ha ha. You are seeing the mounting of the box. The wires aren't fed through into the new box yet. (you sly old fox).

Crossy - is this what you are referring to? I want a joint I can disconnect quickly in case I have to rip the pump out.

Stranded wire I solder before feeding into this (forget the name). You cut it down to about 1/4 inch & then apply a small flat blade screwdriver.

[Crossy]

Ha ha ha. You are seeing the mounting of the box. The wires aren't fed through into the new box yet. (you sly old fox).

Crossy - is this what you are referring to? I want a joint I can disconnect quickly in case I have to rip the pump out.

Stranded wire I solder before feeding into this (forget the name). You cut it down to about 1/4 inch & then apply a small flat blade screwdriver.

Yup, those are what we call 'choc-blocks' for obvious reasons, the brown ones look even more edible Very simple, reasonably safe, certainly 10⁶ times better than the standard Thai 'twist-n-tape' and readily available in various sizes . I've no idea what the official name is although I have heard them called 'barrel' connectors, the RS catalogue simply calls them 'screw connector blocks'.

There is no real need to tin (solder) stranded when using these, a tight twist is fine, if you do tin the ends make sure you don't let the solder wick up under the insulation as noted before, just enough to stop wayward strands will do the trick

The 'proper' way is to use bootlace ferrules (these chaps http://www.csedistributors.com/acatalog/Bo..._Ferrules.html) crimped onto the stranded ends but you'll rarely see that done on domestic installations even in the West.

A favourite trick (one of many) us more 'mature' chaps played on our long suffering apprentices was to splice a cable with a choc-block without stripping the end, looks a good joint but for some reason won't conduct electricity. Hours of fun watching the poor lad scratching his head (whilst we drink the tea he just made), almost as exciting as sending him to the stores for a long weight (they are next to the left-handed screwdrivers and metric hammers).

EDIT I see crimp splices and wire nuts in your picture too, are you training your 'lectric man in the use of these?

Edited August 20, 2008 by Crossy

[dotcom]

I am the only guy that does wiring in my house.

Had to search hard on your site to figure out what MEN is. I thought it had to do with the fermale reproductive system.

M E (Earth) N neutral ?

When the dopes came out to install my 30/100 amp power meter they reversed the wires at the pole. In theory my whole enclosure could have been live. Scared the bejesus out of me.

I forget right now how I discovered the cokk up but it ook my breath away. The idiots could have checked their work with a neon scredriver in less than a minute but are too stupid & bone idle to do so.

Caveat Emptor.

So Crossy. I am thinking to run a lead between my earth & my neutral in my load center. (Since you say it is the code).

I want to try RCCB - tell me who make them in Thailand?

[Crossy]

So Crossy. I am thinking to run a lead between my earth & my neutral in my load center. (Since you say it is the code).

I want to try RCCB - tell me who make them in Thailand?

MEN means Multiple Earthed Neutral, in other countries it gets called PME (Protective Multiple Earthing). It relies on the power company providing multiple points of connection between the neutral and ground, either at every other pole, or, (as we see in Thailand) inside everyones load centre.

It is not wise to install a MEN link if you are not CERTAIN that the whole branch has them. Whilst MEN is Thai code many areas have not yet implemented it and installing the link between neutral and ground could give you issues in the event of a neutral failure (like the whole areas neutral current goes up your MEN link). If you're not sure don't install one!

For your RCCB, pretty well every electrical shop will have the locally favoured Saf-T-Cut units. DIN mount units that fit in your load centre are available from Schneider but you're likely going to have to order them unless you're in a major conurbation.

Schneider do have an online catalogue, I'll see if I can find the link.

[jojothai]

The advice above is good, so long as the joints use wire nuts and are protected in junction boxes you'll be fine.

The UK uses ring mains (unheard of in Thailand) which use a bigger breaker (32A) but the same 2.5mm² cable rated at 20A, which is why you must make all wiring from socket to socket and back to the distribution board to maintain the integrity of the ring. Radial wiring as in Thailand uses a 20A breaker on each run so there is no need for a ring.

It sounds like your chap has got a good handle on safe installations

hi crossy

Can you explain what you mean by radial wiring. Is it parallel circuits rather than a ring?

With respect to making the cable run from socket to socket it is not necessary for all sockets. There are rules with respect to the number of spurs you can have from a circuit. A spur is a single set of cable running from the ring main circuit to a socket. Such as when you put a junction box on the circuit at the top of the wall and run only one set of cable down to the socket, or you run an additional socket from an existing socket which is on the ring.

Normally you should not have more than half your sockets as spurs. ie You should loop in and out for more than half of them.

I am not an electrician and cannot explain the technical reasons but that is the normal rule I am aware.

It is with ring mains but i dont know if the same rule applies with this radial wiring., but I dont see why it should be any different.

regards

Jojothai

[Crossy]

Can you explain what you mean by radial wiring. Is it parallel circuits rather than a ring?

With respect to making the cable run from socket to socket it is not necessary for all sockets. There are rules with respect to the number of spurs you can have ...........

..........It is with ring mains but i dont know if the same rule applies with this radial wiring., but I dont see why it should be any different.

Forget anything you've read about ring mains and spurs, those rules do not apply in Thailand as we do not use ring mains.

Radial wiring is simply a single cable running from the consumer unit to an outlet, then from that outlet to the next and so on, there is no 'return' from the last outlet in the chain back to the consumer unit (doing this would make it a ring main). This radial is protected by a 20A breaker so that the 2.5mm² cable cannot be overloaded.

The Thai's tend to modify this system by actually running the outlets off droppers (and having a joint in the ceiling) rather than 'wasting' cable by running down to the outlet and back up (which I'd rather do, keeps joints out of the roof).

There is no legal limit how many outlets you can have on a radial, but the recommendation is no more than 5 double outlets. So long as the breaker rating is less than the cable rating there is no problem.

The reason for the limits for spurs in the UK is that the breaker rating (32A) is greater than the rating of the cable (20A) so it is quite possible to overload a spur even if it has one double outlet (2x13A) on the end.

Radial wiring is now permitted in the UK, wired with 4mm² cable with a 30A breaker, so once again, the rating of the breaker is less than the rating of the cable

[jojothai]

Thanks Crossy

Explains it very well thanks.

With the radial wiring here do you know what they normally allow for voltage drop calculation.

Is it 3% or 5%?

If I get the calculation right, at 3% and 20 A I think the 2.5mm cable can go up to about 16 metres.

20 A x 0.0102(resistance) x 2 x 16 = 6.5 approx 3% of 220.

Am I correct?

Is the calculation still applicable with the radial circuit, and still use twice the distance.

regards

Jojothai

[Crossy]

With the radial wiring here do you know what they normally allow for voltage drop calculation.

Is it 3% or 5%?

If I get the calculation right, at 3% and 20 A I think the 2.5mm cable can go up to about 16 metres.

20 A x 0.0102(resistance) x 2 x 16 = 6.5 approx 3% of 220.

Sounds pretty close, I use 5% so you can go to 30m or so on a 2.5mm² run, but to be honest the chances of actually pulling 20A from a radial are pretty remote, I doubt many of ours get more than 5A apart from the one with the toaster, kettle and microwave on.

In a domestic situation I wouldn't even bother calculating the drop unless you have a massive house and put 30 outlets on one radial

There's a handy-dandy volt drop calculator here http://www.crossy.co.uk/wiring/VoltageDrop.htm useful for that long run to your water pump

Edited August 22, 2008 by Crossy

[jojothai]

Sounds pretty close, I use 5% so you can go to 30m or so on a 2.5mm² run, but to be honest the chances of actually pulling 20A from a radial are pretty remote, I doubt many of ours get more than 5A apart from the one with the toaster, kettle and microwave on.

In a domestic situation I wouldn't even bother calculating the drop unless you have a massive house and put 30 outlets on one radial

There's a handy-dandy volt drop calculator here http://www.crossy.co.uk/wiring/VoltageDrop.htm useful for that long run to your water pump

Agrees wih my thoughts. Its very unlikely will have the 20 Amp ( approx 4.5 kw) all at the maximum length, very likely less than half of that at extreme so 30 m sounds very good.

The voltage drop calculation is more a check for the larger loads (water heater and cooker) to be sure they are ok with cable size. Other domestic are as you say are normally ok ,provided within 20 amp max load.

Thanks very much for your insight. Much appreciated

jojothai

[Lancashirelad]

Crossy, i bow to your superior knowledge of all things electrical, but just one thing i picked up on..... just down to terminolgy really me thinks:

Choc box

whereas what you were refering to is known as "flex" or "Strip" connector. (the thing sitting inside the choc box). Its far superior & neater than those horrible screw on caps me thinks.

Edited August 26, 2008 by Lancashirelad

[longball53098]

This special box "Choc Box" is a nice gimmick but here in LOS its much simpler to use a standard J-box with coverplate and make your connections inside that box. If your running the double insulated cable such as shown in the article photo and not conduit then just add a J box at the connection point and use strain relief where the cables enter the box.

Choc box is nice but finding them here may be a bit of a problem I think