Domestic Electrical Wiring

[Crossy]

How safe are the electric water units which are hidden in cabinets for example under the sinks in bathrooms etc. Then this one unit provides hot water to the wash asins, shower and ath etc, but is completely out of view and certainly not in the shower itself. Only thing it is near is the water in and outlets under the wash basins.

Provided they are correctly installed, grounded and protected by an ELCB (not in the heater itself but in the distribution board) they are perfectly safe, well as safe as any electric water heater can be, better if you've got PVC pipes to the taps and shower.

Get a good quality, 'known' brand and you'll be fine

[Nawtilus]

Ok Thanks, here are 4 pics of the old style bathroom where we currently live and I would like a safety opinion on these....particulalry for my kids and recommendation to fix if anything wrong. I already know 2 things wrong here, but would like the water heater system in particular to get a look at....

Here is an old switch, hte big cumbersome thing in the middle with red and black button does not seem to work, turn it off and nothing changes, hot water, lights still work. While the breaker above it turns off the hot water system if flicked off.

This shows the earth wire running from the hot water system and connected into the wall, what looks to be onto the water pipe, but the pipe coming out is pvc and not sure what is behind that and the wire is actually connected to ?

The top of the hot water system and earth wire coming out.

Overview of the system, the brown unit on the right is not working, the owner simply put in a new unit next to the old one when we moved in and complained of no real hot water.

Here is the breaker box....pros and cons ?

Edited March 20, 2007 by Nawtilus

[Crossy]

Ok Thanks, here are 4 pics of the old style bathroom where we currently live and I would like a safety opinion on these....particulalry for my kids and recommendation to fix if anything wrong. I already know 2 things wrong here, but would like the water heater system in particular to get a look at....

OK, a quick glance.

The Stiebel Eltron unit is a good quality German item (assuming it's genuine), although I cant find one on their site that looks exactly like yours. http://www.stiebel-eltron.de/en/privatkund...dukte/index.php (yes the site is in English).

You DEFINATELY need to see where that ground wire goes and it doesn't appear thick enough in the photos (could be deceptive).

I don't think that heater is intended to be mounted in a shower area although without the model number I can't be sure. If it's not shower-certified this could be LETHAL!!!!!

You don't appear to have an ELCB for the heater, again I consider this ESSENTIAL.

That old switch could control the old heater (is that why it doesn't work?), had things like that for the aircon units in Malaysia.

[Nawtilus]

It probably was for the old unit, we still have them in the bedrooms for the aircons as well.

Good to know these things and thanks for the advice.

I have an electrician wiring another house and I will drag him around to check it out, knowing what to point out is always best.

I want to get that power outlet taken out also and the light switch changed.

Also can you tell me if ELCB, RCD, MEN are well known terms in Thailand among electricians....decent or not ??

Edited March 20, 2007 by Nawtilus

[Crossy]

Also can you tell me if ELCB, RCD, MEN are well known terms in Thailand among electricians....decent or not ??

ELCB, RCD, GFI, RCCB etc = Safe-T-Cut in Thai

MEN is more difficult, but if you have a Safe-T-Cut the installation guide (hardly a manual) clearly shows a link between the ground and incoming neutral, ie a MEN or PME link

Pictures speak 1000's of words, print out the piccies from http://www.crossy.co.uk/wiring that show the MEN link, the man should understand

[Nawtilus]

Already printed that out earlier today, dont worry i have learnt pictures and diagrams are not just for kindergarden.

Thing is that this guy is a really nice dude, he is even intelligant. But the system I am putting in another house, a control box mood lighting system, he was told how to do it, said he understood and has done it before, understood that the data cable had to be min 30cm from electric wiring running parallel and all was clear.

Few days later he had the data cable and electric running together, at least he did not plan to put them in the same conduit. Points for that.

So he had to go and channel out the walls again in a couple of spots. Now I got channeling everywhere with nowhere to go.

Oh and yes he has mentioned safe T cut already, good to know as i was not sure they knew the other terms as readily recognisable. And now that I am confident STC is the same as the others, job well done....I hope.

Edited March 20, 2007 by Nawtilus

[elkangorito]

Already printed that out earlier today, dont worry i have learnt pictures and diagrams are not just for kindergarden.

Thing is that this guy is a really nice dude, he is even intelligant. But the system I am putting in another house, a control box mood lighting system, he was told how to do it, said he understood and has done it before, understood that the data cable had to be min 30cm from electric wiring running parallel and all was clear.

Few days later he had the data cable and electric running together, at least he did not plan to put them in the same conduit. Points for that.

So he had to go and channel out the walls again in a couple of spots. Now I got channeling everywhere with nowhere to go.

Oh and yes he has mentioned safe T cut already, good to know as i was not sure they knew the other terms as readily recognisable. And now that I am confident STC is the same as the others, job well done....I hope.

Just as long as your earth leakage protection devices (Safe-T-cuts) are non adjustable & 30milli Amp/20 milli Second devices.

[elkangorito]

Already printed that out earlier today, dont worry i have learnt pictures and diagrams are not just for kindergarden.

Thing is that this guy is a really nice dude, he is even intelligant. But the system I am putting in another house, a control box mood lighting system, he was told how to do it, said he understood and has done it before, understood that the data cable had to be min 30cm from electric wiring running parallel and all was clear.

Few days later he had the data cable and electric running together, at least he did not plan to put them in the same conduit. Points for that.

So he had to go and channel out the walls again in a couple of spots. Now I got channeling everywhere with nowhere to go.

Oh and yes he has mentioned safe T cut already, good to know as i was not sure they knew the other terms as readily recognisable. And now that I am confident STC is the same as the others, job well done....I hope.

Just as long as your earth leakage protection devices (Safe-T-cuts) are non adjustable & 30milli Amp/20 milli Second devices.

[Crossy]

OK. Today's subject for discussion is: Wiring buried in plaster.

Standard practice for domestic new-builds in the UK is to fix all the wall boxes for outlets, light switches etc. etc and run the TPS cables between them BEFORE the plasterer does his bit. The cables are run naked with few (no) cable clips, often (but not always) they are covered by a plastic cap strip to prevent damage by the plasterer (the regs. don't actually require this).

The man then plasters over the whole lot (often filling the boxes too, plasterers are notoriously sparks-unfriendly ), no need to cut (and fill) channels etc.

So, is this practical in LoS?

Can I get the wiring done (after the initial wall screed has been applied so it's a marginally flat surface) and get the installation inspected by The Man before covering the lot with the final render? Is there anything in the render used here that may attack the PVC jacket of the cable (PVC is pretty inert, but you never know)?

Cables in the roof space will have conduit for protection from critters that may like to munch on PVC.

I'm not skimping on the cost of conduit (we're not that poor) but I don't believe in paying for something that's not actually necessary

Stupid idea? Comments chaps

[stevejones123]

You should always do the electrical wiring before plastering. The norm is to run the wires through plastic tubes.

[elkangorito]

OK. Today's subject for discussion is: Wiring buried in plaster.

Standard practice for domestic new-builds in the UK is to fix all the wall boxes for outlets, light switches etc. etc and run the TPS cables between them BEFORE the plasterer does his bit. The cables are run naked with few (no) cable clips, often (but not always) they are covered by a plastic cap strip to prevent damage by the plasterer (the regs. don't actually require this).

The man then plasters over the whole lot (often filling the boxes too, plasterers are notoriously sparks-unfriendly ), no need to cut (and fill) channels etc.

So, is this practical in LoS?

Can I get the wiring done (after the initial wall screed has been applied so it's a marginally flat surface) and get the installation inspected by The Man before covering the lot with the final render? Is there anything in the render used here that may attack the PVC jacket of the cable (PVC is pretty inert, but you never know)?

Cables in the roof space will have conduit for protection from critters that may like to munch on PVC.

I'm not skimping on the cost of conduit (we're not that poor) but I don't believe in paying for something that's not actually necessary

Stupid idea? Comments chaps

A question Crossy;

1. Are your walls Bessa Block (hollow concrete blocks) or otherwise?

If your walls are hollow block, I'd be inclined to run rigid (or flexible) conduit inside & pull 'building wire' (bare cables, not TPS) through them. This way, you can always remove/replace or add more cables at another time.

The inspection issue is something that seems to vary between different inspectors. I'll ask my colleagues about inspections.

[Crossy]

1. Are your walls Bessa Block (hollow concrete blocks) or otherwise?

If your walls are hollow block, I'd be inclined to run rigid (or flexible) conduit inside & pull 'building wire' (bare cables, not TPS) through them. This way, you can always remove/replace or add more cables at another time.

The inspection issue is something that seems to vary between different inspectors. I'll ask my colleagues about inspections.

The walls will be the hollow block (we're still at the planning stage). I'd considered using the wall cavity but with the methods used here I'm not convinced that there will be a free route for the conduit from top to bottom that will allow me to put the outlets and switches where I want them rather than where they could get the conduit through. Do like the idea of using building wire though, so conduit it is direct to the wall then screeded / plastered over. We're wiring for data too, so it's just more of the same

I might even consider a drywall lining rather than screed, lots of space behind that for additions and better heat insulation

[Khonwan]

OK. Today's subject for discussion is: Wiring buried in plaster.

Standard practice for domestic new-builds in the UK is to fix all the wall boxes for outlets, light switches etc. etc and run the TPS cables between them BEFORE the plasterer does his bit. The cables are run naked with few (no) cable clips, often (but not always) they are covered by a plastic cap strip to prevent damage by the plasterer (the regs. don't actually require this).

The man then plasters over the whole lot (often filling the boxes too, plasterers are notoriously sparks-unfriendly ), no need to cut (and fill) channels etc.

So, is this practical in LoS?

Can I get the wiring done (after the initial wall screed has been applied so it's a marginally flat surface) and get the installation inspected by The Man before covering the lot with the final render? Is there anything in the render used here that may attack the PVC jacket of the cable (PVC is pretty inert, but you never know)?

Cables in the roof space will have conduit for protection from critters that may like to munch on PVC.

I'm not skimping on the cost of conduit (we're not that poor) but I don't believe in paying for something that's not actually necessary

Stupid idea? Comments chaps

Stupid idea? Not sure - but that's basically what I did 11 years ago. I simply laid single-core cables to the bare brick walls and had my labourers plaster over them. I've never had a problem.

[elkangorito]

The laying of bare wires or even TPS cables on a wall & then covering them with plaster/render etc, is illegal in Australia. The reason being is that anybody could belt nails or other fixings into the walls to hang things, which could penetrate the cable & create a hazard. From a safety point of view, I would install the cables/wires in rigid electrical conduit. This allows for the easy replacement of cable at a later date. If the wall is concrete or similar, a groove is chiseled into the wall (prior to rendering), which is deep enough for the diameter of the conduit.

Imagine having a wiring fault & then having to rip half the wall off to fix it? The use of conduit eliminates this problem.

Edited March 23, 2007 by elkangorito

[Khonwan]

The laying of bare wires or even TPS cables on a wall & then covering them with plaster/render etc, is illegal in Australia. The reason being is that anybody could belt nails or other fixings into the walls to hang things, which could penetrate the cable & create a hazard. From a safety point of view, I would install the cables/wires in rigid electrical conduit. This allows for the easy replacement of cable at a later date. If the wall is concrete or similar, a groove is chiseled into the wall (prior to rendering), which is deep enough for the diameter of the conduit.

Imagine having a wiring fault & then having to rip half the wall off to fix it? The use of conduit eliminates this problem.

I acknowledge this represents best advice. In my individual case, I check with a hand-held voltage (and metal) detector before hammering nails. Still, your advice is best, especially in terms of your last point. I'm sure I would do it your way were I to do it for another new building.

BTW, chiseling a groove for hundreds of metres in my house would have been a nightmare - a 4" angle grinder would do the job very quickly.

[technocracy]

OK. Today's subject for discussion is: Wiring buried in plaster.

Standard practice for domestic new-builds in the UK is to fix all the wall boxes for outlets, light switches etc. etc and run the TPS cables between them BEFORE the plasterer does his bit. The cables are run naked with few (no) cable clips, often (but not always) they are covered by a plastic cap strip to prevent damage by the plasterer (the regs. don't actually require this).

The man then plasters over the whole lot (often filling the boxes too, plasterers are notoriously sparks-unfriendly ), no need to cut (and fill) channels etc.

So, is this practical in LoS?

Can I get the wiring done (after the initial wall screed has been applied so it's a marginally flat surface) and get the installation inspected by The Man before covering the lot with the final render? Is there anything in the render used here that may attack the PVC jacket of the cable (PVC is pretty inert, but you never know)?

Cables in the roof space will have conduit for protection from critters that may like to munch on PVC.

I'm not skimping on the cost of conduit (we're not that poor) but I don't believe in paying for something that's not actually necessary

Stupid idea? Comments chaps

Fun you should ask such as question!

Today I have been pulling TPS through 20mm conduit - easy stuff - it's just doing cutting all the conduit and pulling through 3 ways which are a bit a pain in the butt.

Here in Laos its the norm for all the conduit runs and boxes to be cut in ready for them to take the ceiling and the render. The render is plain and simple cement mix with fine sand. Also the houses are built from the orange brick rather than these concrete blocks so it's nice and easy to chase the runs in. A 4" angle grinder with concrete blade, goggles, gloves and dust mask and off you go!!

The ones I have been running in today haven't been rendered over yet - but that is only because the ceiling guys have finished there work in these rooms and the renders haven't got there yet. Other room the conduit and boxes have all been rendered over already.

I did consider the bare/single core wires in conduit approach but as TPS was available I'd use it. As I am also used to the UK approach I was a little nervous about them rendering over the conduit as of possible difficults of running the cables in - but just tape the ends of the TPS together and it just glides down no hassle.

The cement render is also laid on pretty thick so you don't need to sink the conduit completely in, just sticking out is plenty.

Hope that helps! Time to go and sink a few beers - tomorrow one the lighting radial the builder today was amazed at how quickly I had two radials run in - I just said I don't work to Lao time!

[Crossy]

The laying of bare wires or even TPS cables on a wall & then covering them with plaster/render etc, is illegal in Australia. The reason being is that anybody could belt nails or other fixings into the walls to hang things, which could penetrate the cable & create a hazard. From a safety point of view, I would install the cables/wires in rigid electrical conduit. This allows for the easy replacement of cable at a later date. If the wall is concrete or similar, a groove is chiseled into the wall (prior to rendering), which is deep enough for the diameter of the conduit.

Imagine having a wiring fault & then having to rip half the wall off to fix it? The use of conduit eliminates this problem.

To be honest, how many times have you had a domestic wiring failure that needed the cable replacing? Never I suspect, but the problem of someone bashing a nail through the wiring is a worry.

In the UK I always assumed it was OK if you didn't nail above a light switch or below / between wall outlets (power invariably comes up from the floor). That was until I saw a new house being wired, TPS taking the shortest route from the light switch to the light fitting, straight across the wall at 45 degrees, I bought a wire and pipe detector

I'll be using conduit, with whatever comes out cheaper TPS or building wire. TPS has the advantage that you know which pair of black / white wires belong together, important if using individual RCD/MCB units

[elkangorito]

The laying of bare wires or even TPS cables on a wall & then covering them with plaster/render etc, is illegal in Australia. The reason being is that anybody could belt nails or other fixings into the walls to hang things, which could penetrate the cable & create a hazard. From a safety point of view, I would install the cables/wires in rigid electrical conduit. This allows for the easy replacement of cable at a later date. If the wall is concrete or similar, a groove is chiseled into the wall (prior to rendering), which is deep enough for the diameter of the conduit.

Imagine having a wiring fault & then having to rip half the wall off to fix it? The use of conduit eliminates this problem.

To be honest, how many times have you had a domestic wiring failure that needed the cable replacing? Never I suspect, but the problem of someone bashing a nail through the wiring is a worry.

In the UK I always assumed it was OK if you didn't nail above a light switch or below / between wall outlets (power invariably comes up from the floor). That was until I saw a new house being wired, TPS taking the shortest route from the light switch to the light fitting, straight across the wall at 45 degrees, I bought a wire and pipe detector

I'll be using conduit, with whatever comes out cheaper TPS or building wire. TPS has the advantage that you know which pair of black / white wires belong together, important if using individual RCD/MCB units

Actually, I've had to replace 'in the wall' wiring a few times. The wiring was actually burnt due to a faulty plug, which created a resistive join. On other occassions, the installing electrician had screwed the wires into the GPO to tightly, which then slowly became resistive, which then burnt the wiring.

[Crossy]

Actually, I've had to replace 'in the wall' wiring a few times. The wiring was actually burnt due to a faulty plug, which created a resistive join. On other occassions, the installing electrician had screwed the wires into the GPO to tightly, which then slowly became resistive, which then burnt the wiring.

and of course the tails were too short to re-make the connection (I feel for you), whatever happened to the rule to make the tails long enough to re-make twice?

[elkangorito]

Actually, I've had to replace 'in the wall' wiring a few times. The wiring was actually burnt due to a faulty plug, which created a resistive join. On other occassions, the installing electrician had screwed the wires into the GPO to tightly, which then slowly became resistive, which then burnt the wiring.

and of course the tails were too short to re-make the connection (I feel for you), whatever happened to the rule to make the tails long enough to re-make twice?

Darn right about that Crossy...tails were too short. I normally leave about 30cm (1 foot) in case of such problems. As you know, burnt wiring must be cut back quite a way before you get to the unaffected copper.

[Crossy]

Darn right about that Crossy...tails were too short. I normally leave about 30cm (1 foot) in case of such problems. As you know, burnt wiring must be cut back quite a way before you get to the unaffected copper.

We don't seem to get much problem with fried wiring in the UK. Possibly because the BS1363 outlets are big, chunky (and 'kin expensive) things that have a fair distance between the contacts (which can get hot) and the cable connections, I've pulled a few badly scorched outlets (cheap, ill-fitting plug with a 3kW fan heater on the end, arc fizz fizz arc), the incoming cables were totally unaffected

IIRC the Aussie ones are similar in dimensions to the US (and Thai) style with the cable pretty close to the contacts where they can get readily toasted

[elkangorito]

Darn right about that Crossy...tails were too short. I normally leave about 30cm (1 foot) in case of such problems. As you know, burnt wiring must be cut back quite a way before you get to the unaffected copper.

We don't seem to get much problem with fried wiring in the UK. Possibly because the BS1363 outlets are big, chunky (and 'kin expensive) things that have a fair distance between the contacts (which can get hot) and the cable connections, I've pulled a few badly scorched outlets (cheap, ill-fitting plug with a 3kW fan heater on the end, arc fizz fizz arc), the incoming cables were totally unaffected

IIRC the Aussie ones are similar in dimensions to the US (and Thai) style with the cable pretty close to the contacts where they can get readily toasted

That they are Crossy...that they are.

[elkangorito]

Selection of Relays & Contactors.

When controlling equipment with timers etc, it is quite often advisable to not use the contacts in the timer. An example would be the use of a timer to control a >2kW motor (inductive) or a bank of 20 or more 'power factor corrected' fluorescent lights (capacitive). Although these loads are not big, it is the type of load that is important, typically inductive or capacitive. Both of these loads can quickly degrade electrical contacts to the point of failure. The cost of a 7 day 24 hour programmable timer far outweighs the cost of a relay or contactor. If the contacts in the timer burn out, you must buy a new one. On the other hand, if you use a contactor or relay to switch the load, you will protect the expensive timers contacts.

Contactors & relays are designed to switch certain types of loads, especially inductive & capacitive loads, & last for a long time. These devices typically have ratings to indicate what size of what type of load their contacts can handle. Most quality contactors & relays have an 'AC' rating. For resistive loads, AC1 is indicated. For capacitive & inductive loads, AC3 is indicated & for inductive 'inching & plugging' (rapid stopping & starting of a motor)loads, AC4 is indicated.

Eg. You have a motor rated at 5.5kW. If you select a contactor that is rated for 5kW AC1, the contactors life will be noticeably reduced. Also, these devices are sensitive to fault current & must be protected appropriately.

So, if you don't want to burn out your expensive timer etc, use an interposing relay/contactor to do the job.

Edited March 27, 2007 by elkangorito

[gcad]

The laying of bare wires or even TPS cables on a wall & then covering them with plaster/render etc, is illegal in Australia.

Not necessarily. It depends on your interpretation of the rules, which, I believe refer to a cable not being subject to mechanical damage.

I have wired solid brick buildings with this wire chasing method numerous times.

The only thing I have been weary of is not chasing cables diagonally or horizontally across walls.

[gcad]

Selection of Relays & Contactors.

Eg. You have a motor rated at 5.5kW. If you select a contactor that is rated for 5kW AC1, the contactors life will be noticeably reduced. Also, these devices are sensitive to fault current & must be protected appropriately.

So, if you don't want to burn out your expensive timer etc, use an interposing relay/contactor to do the job.

And if you've had a hard night out, don't install the contactor upside-down and accidentally use the N.O. (13 & 14) contacts for your motor because those contacts are usually only rated up to 10A.

Not that I've ever done this.

[elkangorito]

The laying of bare wires or even TPS cables on a wall & then covering them with plaster/render etc, is illegal in Australia.

Not necessarily. It depends on your interpretation of the rules, which, I believe refer to a cable not being subject to mechanical damage.

I have wired solid brick buildings with this wire chasing method numerous times.

The only thing I have been weary of is not chasing cables diagonally or horizontally across walls.

Here is the excerpt from the rules plus other associated stuff;

3.3.7 Impact.

A wiring system shall be selected and installed so as to minimize mechanical damage. Protection against mechanical damage shall be provided by one or any

combination of the following:

[a] Mechanical characteristics of the wiring system.

Location selected.

[c] Provision of additional local or general mechanical protection.

3.3.8 Vibration.

A wiring system supported by, or fixed to, a structure or equipment subject to vibration likely to cause damage to the wiring system, including all cables, fixings and connections shall be suitable for the conditions.

3.3.9 Other mechanical stresses.

A wiring system shall be selected and installed so as to minimize damage to the sheath and insulation of cables and insulated conductors and their connections during installation, use and maintenance. The radius of every bend in a wiring system shall be such that conductors and cables shall not suffer damage. Where a conductor or a cable is not resting on a continuous surface it shall be supported by suitable means at appropriate intervals in such a manner that the conductor or cable does not suffer damage by its own weight.

Every cable or conductor used as fixed wiring shall be supported in such a way that it is not exposed to undue mechanical strain and so that there is no appreciable mechanical strain on the connections of the conductors, account being taken of mechanical strain imposed by the supported weight of the cable or conductor itself.

A flexible wiring system shall be installed so that excessive tensile and torsional stresses to the conductors and connections are avoided.

I would choose to err on the safe side by not chasing cables directly into a wall which, at some stage, may be subject to mechanical interference. An example of this would be someone belting masonry nails into a rendered wall in order to hang something. To me, this constitutes a failure to protect the cable against mechanical damage should the cables not be adequately protected by means of conduit etc.

[chownah]

Most conduit I've seen would not stop a masonry nail.

[elkangorito]

Most conduit I've seen would not stop a masonry nail.

Maybe this is why the Thais have the wiring 'exposed'? I suppose then the only thing that can happen to the wiring is that it can get belted & damaged by all & sundry, moving furniture & other such sharp edged things.

Try belting a nail into conduit...it's more difficult than you think. And I mean electrical conduit...not any other kind.

[Crossy]

The IEE regs (paragraphs 522.6, 7 & 8 in the 17th Edition) have very similar wording to the Oz ones (same root I suspect). It's open to interpretation, certainly unprotected cable (surface or buried) is OK in domestic environments, industrial is a whole different ball game, obviously our lives are less valuable when at home

The screed I've seen here is so bl00dy hard that the only practical option is to drill a hole, PVC conduit is definately not going to stop that.

[elkangorito]

The IEE regs (paragraphs 522.6, 7 & 8 in the 17th Edition) have very similar wording to the Oz ones (same root I suspect). It's open to interpretation, certainly unprotected cable (surface or buried) is OK in domestic environments, industrial is a whole different ball game, obviously our lives are less valuable when at home

The screed I've seen here is so bl00dy hard that the only practical option is to drill a hole, PVC conduit is definately not going to stop that.

Got to agree with you that one Crossy. At the end of the day, you can't protect against everything. I still think that conduit is better than nothing.

Actually, the Oz rules come from you European fellas...all we did was change a few things in the 'normalisation' process for Oz conditions.