Consumer Unit Installation (electrical)

[MattFS218]

I purchased an ABB Consumer Unit set to install at my girlfriend's house in Isan. The set includes the CU, MCB, RCD, and 4 Mini Circuit Breakers.

I'm planning on following the diagram here

and so far I've done this

I'm told I should use 10 mm2 wiring for the wires inside the CU connecting the MCB, RCD, Neutral Bar and Ground Bar. The wires in the picture are the same wires from the incoming meter feed (which are 10 mm2), but to me they look and seem rather large. Am I using the correct wire size? Can I get 10 mm2 wiring with less insulation and thus make it less bulky?

Also, what's the recommended size wire for connecting the ground bar and the 1.8m copper wire ground? Crossy's site says 4 mm2, but the sales person who sold it recommends 6 mm2. Thanks

[Crossy]

If you are using the same cable as your incoming, this is double insulated to protect it from the rigours of an outdoor installation. You can get single insulated 10mm which has much thinner insulation (buy it by the metre).

If you use the less bulky wire then it will be easier to butt the insulation up against the MCBs etc. Avoid leaving any copper visible.

You may be able to run the wire from the incoming breaker to the ELCB underneath the DIN mounting rail rather than round the end, making a neater installation. You should also use the correct wire colours, Black for live, White or Grey for neutral, Green or Green/Yellow for ground.

Using 6mm to your ground rod will do no harm, the updated UK regs say 6mm, Oz says 4mm take your pick

Personally I don't like the Thai method of feeding the neutral via the ground bar and would much rather link the neutral to the ground bar with a separate removable MEN link on the cold side of the incoming breaker (not the ELCB) and feed both incoming live and neutral direct to the hot side of the breaker.

As you have a separate incomer/ELCB you may want to add an unprotected breaker to run your freezer, avoids problems should your ELCB trip whilst you're away. Put it between the incomer and ELCB so it's obvious it's unprotected, link to the live on the cold end of the incomer with a short length of 2.5mm.

You may want to tape up the unused portion of the live bus-bar.

Edited October 16, 2008 by Crossy

[MattFS218]

Thank you Crossy,

Your website and information (I've been reading over your posts on TV for the past 3-4 hrs) has undoubtedly saved many lives.

One more quick question. A hot water heater was installed prior to this CU installation and has a separate ground coming directly out of the hot water heater into its own stake in the ground. Is it OK to leave this hot water ground intact when upgrading my CU and grounding it? Would it be better to connect it to the new MEN Ground in the CU? I don't have 3 core wiring, so I would need to run another wire just for the ground if I were to do so.

The dedicated hot water ground and the new CU ground are about 1.5-2 meters apart, is this sufficient distance?

Thanks again.

--matt

[Crossy]

Matt.

Your water heater will be quite safe as it is, although you have an ELCB do check the ground is well connected.

If you follow the UK or Oz regs to the letter you should connect the heater ground to the MEN, to be honest unless it's an easy wiring run, I wouldn't bother.

I wish I had more time to maintain the website, unfortunately earning a crust takes priority

[mdechgan]

I'm sure Crossy doesn't like how the neutral is grounded.

[MattFS218]

Hi Crossy,

One more quick question...on your page http://www.crossy.co.uk/wiring/elcb.html it says to ensure the RCD tripping current is under 30 milliamps. Is there anyway you can tell from this closeup picture if the RCD I purchased qualifies under this amount. I know this RCD matches with my 40amp Main Circuit Breaker, but admit I didn't come across your page until after I purchased this set of electrical items and am sorta trusting the sales person's word that this was a good solution.

--matt

Edited October 16, 2008 by MattFS218

[mdechgan]

How much did the entire unit cost?

What's the best way to hook it up if there is no utility fuse or utility isolator or main service disconnect?

I always hated handling hot wires.

Edited October 16, 2008 by mdechgan

[Crossy]

Matt

That is a 30mA ELCB, the line 40A I_{(delta n)}=0.03A is the spec. (delta is the triangle thing) 0.03A=30mA good for the job

Mdechgan

Yup, I hate the neutral-ground connection method, if you do the installation tests to UK or Oz regs you must disconnect the MEN link which is impossible with this arrangement.

If you have to handle hot wires rubber gloves and strong boots (both dry) will reduce the possiblility of a shock, or just get your sparks to hook it up

Edited October 16, 2008 by Crossy

[MattFS218]

How much did the entire unit cost?

What's the best way to hook it up if there is no utility fuse or utility isolator or main service disconnect?

I always hated handling hot wires.

My brother-in-law will do the physical hookup by disconnecting the main service first, so I'm not worried myself about handling the hot wires.

The CU box costs 1090 baht

The Main Circuit Breaker was like 800 baht

The RCD was like 1750 baht

The 3 16amp Mini Circuit Breakers were like 200 each

and the 1 20 amp Mini Circuit Breaker was also like 200 baht

so I think like 4000 baht total.

[MattFS218]

As you have a separate incomer/ELCB you may want to add an unprotected breaker to run your freezer, avoids problems should your ELCB trip whilst you're away. Put it between the incomer and ELCB so it's obvious it's unprotected, link to the live on the cold end of the incomer with a short length of 2.5mm.

I'm going to install the fridge on the RCD first, and see how often the breaks occur. The fridge at my gf's house is really old, and the plug is only 2 pin (i'm not sure if it was like this originally, or if it was modified thai electrical engineer style

If it trips too often tho, you suggest I move one circuit breaker in between the Main Circuit Breaker and the RCD (so anyone else looking at the system would know it's unprotected). Then I would connect 2 wires from the Main Circuit Breakers Live (2nd bottom on the Main CB) to both the RCD Live (2nd top on RCD) and the unprotected Mini Circuit Breaker Live (bottom of the Mini CB) for the Fridge. The neutral coming back from the fridge I would connect directly to the Main Circuit Breaker Neutral (1st bottom) along with the RCD's Neutral.

If I did this wouldn't I need to use 10 sq mm wire between the main CB and the mini CB for the fridge because it's a 40 amp main breaker?

thanks.

--matt

Edited October 16, 2008 by MattFS218

[MattFS218]

Okay, okay...more questions keep coming to mind.

The gf called the power company today and asked if the MEN system was available in rural Nongkhai where the house is. The person who answered the phone didn't know precisely what a MEN system was, but said it was OK to install a ground on what was described to him as a recently purchased consumer unit from bangkok. The person who he said would know was not in the office today. I intend to call back tomorrow to get a definitive answer.

I did however wonder outside and noticed that on several of our electricity polls in the village there is a connection of some sort running into the ground. It's on about every 3rd post. In fact, the next poll over (walking away from the main transformer has one). I assume this is a ground, but is this sufficient enough to assume that this area has a MEN system?

--matt

[mdechgan]

I've noticed ground wires on a few poles myself. But I don't think they are connected to ground. I think they are just for lightning strikes since they run up to the top of the pole.

[dotcom]

What is the rating of your electric meter on the pole?

For me I feel you need a main switch to de-energize the breaker box for doing connection. Square D make them. They have a handle on the side.

I'll try & get a picture.

[dotcom]

Cut-out switch to de-energize your CU. Means you only have to disconnect from power meter once.

Looking good so far.

Edited October 16, 2008 by dotcom

[Crossy]

Matt

Theoretically you are correct, the single breaker for the fridge should be fed with 10mm and if you have some, use it. In reality, 2" of 2.5mm will quite happily drop a 40A breaker in the (highly unlikely) event of a short inside your CU.

See this page for the correct wiring of a split-service CU http://www.crossy.co.uk/wiring/Consumer.html you won't actually have a 'protected neutral bar' with only one MCB, but you get the idea.

If you wire the CU assuming MEN is NOT available it is easy to retrofit a MEN link if you find it is. Most definately don't wire for MEN if you're not sure, this could result in a hazard.

Grounds on the poles could be an indication of MEN, get your binoculars out and see if the are connected to the neutral conductor at the top of the pole, if they are you can be pretty confident that you have MEN

Dotcom

On such a small service I don't think an additional isolator is really required, the incomer in the CU will isolate everything except the meter tails which would be unlikely to need moving once installed. There 'should' be a service fuse somewhere near the meter which can be pulled if necessary.

[mdechgan]

So Crossy, which one is the neutral wire? is it the top most wire or the botom most?

If you add a cut out I think the grounding will have to be changed because neutral is only to be grounded at the main service disconnect. The cut out will become the main service disconnect.

In a small service like this I think the main breaker is the main disconnect. The left most breaker in the box.

However I still don't see service fuses at the meters. I think the MEA just splices the wires at the pole. No fuse, no main disconnect. The main fuses are at the local transformers but these are high voltage fuses. If they want to cut your service they just remove the meter and cover the bare ends with electrical tape.

Edited October 17, 2008 by mdechgan

[dotcom]

I just assumed you knew you need to sink your own ground rod.

Crossy. I have never seen any kind of fuses out on the pole (near meter).

mdechan. Still waiting to hear what size power meter you have to discuss wire size although I assume 10 mm will be fine for your 40 amp installation.

Hopefully your meter is one of the new style 15/45 amp.

Edited October 17, 2008 by dotcom

[MattFS218]

I've installed the unit, but want to quadruple check some items (so I can breath easier). I had this discussion a different forum, and there was a kind person who was concerned about my load capacity.

My girlfriend's house is in rural Nongkhai, and has a "5 (amp?) meter". Knowing this is there anything I should change about my installation? I'm using hot water, tv, fridge, laptop computer, 22in flat screen monitor, a cellular phone repeating device (to get a better internet signal), lights, and a dvd player. Is my load too much for this type of meter? is it dangerous to overload the meter? I've read on other posts that typically the thai 5 amp meters usually pull 2-3 times the amount 10-15amps (in my case) without any problems. My assumption is the worst that can happen is I blow the meter fuse.

My girlfriend's sister has an unused house next door on a separate 5 meter (goes to a different main line also). On this, runs my gf's house's 30m deep water pump, and my 12700BTU Mr. Slim A/C. The installation is totally separate and not mixed at all. I know I probably should upgrade the meter, but I don't have 4000 baht around to upgrade, and I'm told there's an additional 100 baht tax per month when you use the bigger meter. I know this isn't 100% ethical, and I'm sure in a developed nation nobody would do this, but I only barely survive here 2 months max a year as I can't get used to the mosquitoes, climate, or hygene of this place. I only do it cause my gf's son lives here, and they like being together as often as they can.

Is everything still OK from my installation perspective?

My next question is about MEN. I did end up hooking up the ground, I had my girlfriend call the local electric company 4 times to check that it was OK to install a ground (they never acknowledge having a MEN system, but they did say it was OK to install a ground...one person from the electric company over phone did however ask why we wanted to install a ground and said there was no need and went on to say only rich houses have a ground). We also took a trip into the Ampur to show the person the diagram we were following and they again said it was OK. They recommended using a 10 sq mm wire to connect the ground. I then took my binoculars and double checked that the wires I noticed going into the ground from the electric pools connected to the neutral. They in fact did, but not at the frequency of polls I had originally thought. The grounds from the electric polls only seemed to connect at the neutral at the poll right before the villages one transformer, and at the termination point for lines away from the village. Assuming I'm the only house in this village that has a ground, and knowing the grounds I saw, I'd guess that my ground provides a "most direct" ground for maybe 15-20 house holds given the wire distance to the closest grounding point. I know nothing about the MEN system, but is this safe for me, and do the benefits of having a ground outweigh the drawbacks in my case. I'm assuming, since I don't understand the MEN system, that there are no other ways to direct a faulty neutral current to flow back down my meter and into my ground. The other concern, is that the grounds on the polls appear to be using a silver colored wiring (i'll take a pic tomorrow, but it appears to be similar to the heavy wiring used to structurally holdup the poles). Is my 10 sq mm copper cable and ground rod going to be an easier path for bad current to flow thru?

Thanks guys.

Edited October 17, 2008 by MattFS218

[dotcom]

I think Crossy is going to tell you NOT TO use a MEN unless you are 100% sure of what you are doing.

5/15 Amp is the smallest meter they sell.

Obviously one 12,000 btu air con means you are right at the limit.

Whether you want to upgrade or not you have to decide. For the house you live in - it seems 15 AMP will be OK. Umness & until you add more stuff.

If money is a problem don't worry about it.

DO NOT TRUST ANY "GROUNDS" at the poles. The wire you are seeing is aluminum. Run your own ground. Keep Earth & Neutral separate. UNLESS I am corrected by Crossy.

Edited October 17, 2008 by dotcom

[mdechgan]

5/15 amp is ok as long as there is no a/c unit running. If there is an a/c no exceptions, have to get a 15/45 amp meter. A 12,000 btu unit already runs at about 7 amps. Computer and 22" monitor are atleast 1-2 amps. Fridge another 1 amp, tv atleast another amp. You will be ok as long as you don't use your water heater and a/c at the same time. But if they are different circuits and meters then you are ok. Just remember the 15 amp limit per meter. However at 15 amps the meter is going to spin really fast. Might even spin faster than it should.

[Crossy]

Whether MEN is implemented or not you need your own ground, period!

The question is whether to connect ground and neutral at your consumer unit.

From what is being described on the poles (multiple grounding of the neutral) I suggest that MEN is actually implemented so you can install a MEN link and not run into hazard in the event of an open neutral (the main reason that MEN was slow to catch on in the UK).

BUT

There is a lot of conjecture on the IEE forums as to whether MEN (or PME as it's known in the UK) actually has any advantage when all circuits are protected by an ELCB (this is now required by the IEE regs 17th edition except under very specific circumstances).

There are also known issues in Thailand with accidental reversal of live and neutral at the meter (usually during work or meter changes). If this happens and you have MEN all exposed metalwork in your home will become live! or at least live enough to be uncomfortable if you touch it (the actual touch voltage will depend upon how good your local ground is). A TV member actually had this happen when the crew hooked up a supply for a wedding celebration and managed to swap the wires at the meter.

If we were in the UK I wouldn't hesitate to install the MEN link, in rural Thailand I would think very carefully before doing so.

[MattFS218]

So I already installed the MEN link. But I do worry about any one of those 15-20 meters that I provide the the most direct ground link for somehow messing up and making my neutral line live.

My question now is, should I now remove the ground? or rewire my CU to not use the MEN link? To be honest, currently none of appliances have 3 plugs (only my monitor has a 'Schuko' Plug, but I haven't gotten around to buying a ground adapter for it yet) and besides the neutral (both meter and Main CB), and the wire to the ground link there's nothing else currently hooked up to my ground bar (or is it called MEN link). Someone on another forum said that having the MEN link will help the RCD trip more easily, or quicker.

I don't live at my girlfriend's house most of time, so I can't watch over this electrical installation like I might normally do, so I'm sort of in a position of am I making the electrical too safe, and too complicated for a normal thai to fix, should something break.

[MattFS218]

Might even spin faster than it should.

mdechgan, when you say might even spin faster than it should...do you mean that I might have to pay for more electricity than I'm using, or that it might spin even faster than 15amps worth (ie, I could pull 16 amps)?

--matt

[MattFS218]

Pictures of my village's MEN (I hope) system....

This is a picture of how my meter connects to the electricity lines. The two circles are the wires that connect me. The top, non-insulated wire I'm assuming is my neutral (because it's the wire that's grounded later in the next few pictures. It's also the wire that ALL the meters connect to, as opposed to rotating between wire 1, and wire 2 for the 2 live wires underneath)

Ground 1, is the closest electricity poll ground to my house, it's about 8 houses down. You wire coming out of the concrete hole (it's circled in red) loops to the other side, and goes all the way into the ground. The red underline is where it connects to my suspected neutral wire.

Ground 2, is the next closest ground, and it's on the poll right before the village's transformer. There's about 10 houses between my house and this poll. It's vary similar to ground 1 in that the aluminum non-insulated wire loops through the concrete pool and connects to the top (I believe) to be neutral wire. I've circled where it connects, and underlined the wiring looping through the top of the concrete poll

This is a picture of the same wire that loops through the concrete at the top of the poll, going into the conduit. This eventually goes into the ground

Again, the conduit going into the ground, where I hope it's grounded and very deep.

I'm also pretty sure this village has a MEN system. When I talked to the person at the electric department I asked specifically about connecting the neutral wire from the meter to the ground, and they said it was OK. I'm double confident (by thai standards) because he went on to say that be sure you are only connecting the neutral wire to the ground, because if you connect the live wire you die...

--matt

Edited October 18, 2008 by MattFS218

[MattFS218]

Hrm...i guess there's only a certain time frame I can edit posts until.

Anyway, I was rereading the thread, and I understand the difference between connecting the Neutral to the Ground at the CU as a MEN link (which is how my installation currently is) as opposed to grounding only my appliances.

So I guess the question is, should I disconnect the MEN link?

Crossy, given the information I've presented, would you disconnect the MEN link? You told me to "think twice" but honestly I don't completely understand this enough to feel confident with my decision (I trust you more ).

If I disconnect the MEN link, I would put the neutral from the meter directly into the Main CB. The only thing connected to my local ground bar would be my (so far non existent) appliance grounds. correct?

Edited October 18, 2008 by MattFS218

[mdechgan]

Might even spin faster than it should.

mdechgan, when you say might even spin faster than it should...do you mean that I might have to pay for more electricity than I'm using, or that it might spin even faster than 15amps worth (ie, I could pull 16 amps)?

--matt

I'm not sure but I've done some simple comparisons before.

The theory is the internal wirings and specs of a 5 amp meter and a 15 amp meter are very different. Lets just say a 15 amp meter is more robust. If using a 5 amp meter at its limits where it was designed the meter could overheat, spin faster than its designed to or supposed to, possibly even adding more resistance, and even be inaccurate at faster than normal speeds. So more energy required to power your house and energy wasted at the meter as heat, etc. I guarantee that the meter the MEA gives out are not top quality.

In simple terms, if one wires the house so that the voltage doesn't drop or energy isn't wasted during the wiring runs. Why forget the meter?

Since the meters in Thailand are mechanical not solid state. The meters do take account potential and kinetic energy to turn. More faster, more kinetic energy, its called creep. Larger meters are more resistance to currents and tend to not spin out of control like smaller meters. So they are less likely to creep.

However if comparing meter rates I'm not sure if it worth the extra 100 baht per month or extra 4,000 baht deposit. I just think at 15 amps a 15 amp meter will be more accurate than a 5 amp meter running at 15 amps.

Does anyone agree or makes sense?

Edited October 18, 2008 by mdechgan

[Crossy]

Crossy, given the information I've presented, would you disconnect the MEN link? You told me to "think twice" but honestly I don't completely understand this enough to feel confident with my decision (I trust you more ).

If I disconnect the MEN link, I would put the neutral from the meter directly into the Main CB. The only thing connected to my local ground bar would be my (so far non existent) appliance grounds. correct?

Given the piccies I would leave it connected, but be aware if any work is done on your meter to verify that live still is live and neutral still is neutral just in case

Personally, I would take both incoming live and neutral direct to the breaker and link the neutral to the ground bar on the cold side of the breaker. This would ensure that in the (hopefully remote) event of L and N being reversed opening the breaker would disconnect your grounded equipment from the (incorrectly) live wire.

Without the MEN you should just have your ground stake and outlet grounds going to the ground bar.

How about some picces of your completed installation, for constructive comment of course.

Edited October 18, 2008 by Crossy

[MattFS218]

How about some picces of your completed installation, for constructive comment of course.

I'll get the pics for you, but give me a week. I don't have enough trust to unscrew the top plastic layer of the CU without disconnecting the meter and I don't really know how to disconnect the meter without my brother-in-law. I did not actually do the install, I just instructed my brother-in-law on how to do it, and to be honest I sorta lost "face" a few times because I thought he understood where wires should have gone when he actually didn't (in his defense tho, I moved around some things last minute...like having 1 circuit be unprotected, as you had suggested). This on top of the fact I've complained about some other quality issues of some recent renovations he has done. I'll ask him to open it up and I'll take a pic next week. I'll probably move the ground bar to the cold side of the main circuit breaker as you also suggested.

One question about doing that though....

The neutral and live from the meter will feed directly to the Main Circuit Breaker

The neutral on the Cold side of the Main CB will have 3 wires, 1 to the ground bar, 1 to the unprotected Mini CB, and 1 to the RCD

All my grounds would still connect to the Ground Bar (is it still called a MEN, or only a Ground Bar now?)

are there any drawbacks from putting the Ground Bar on the cold side of the Main CB? It sort of worries me that ABB didn't think of this when publishing their brochure...but i worry to the point where my brother-in-law now thinks i'm crazy

--matt

[MattFS218]

Oh....i forgot to add, that I also found out both my gf's house and sister's house next door use white wire for LIVE and black for neutral.....yesterday was a very stressful day

[Crossy]

The neutral and live from the meter will feed directly to the Main Circuit Breaker

The neutral on the Cold side of the Main CB will have 3 wires, 1 to the ground bar, 1 to the unprotected Mini CB, and 1 to the RCD

All my grounds would still connect to the Ground Bar (is it still called a MEN, or only a Ground Bar now?)

are there any drawbacks from putting the Ground Bar on the cold side of the Main CB? It sort of worries me that ABB didn't think of this when publishing their brochure...but i worry to the point where my brother-in-law now thinks i'm crazy

You are completely correct, the cold side of your incomer will have three wires in the neutral

With the link to the ground bar it is still MEN, this is how we would wire it in the UK. It means that opening the breaker completely isolates your installation from the incoming supply, very safe even if some bright spark swaps L & N.

Interestingly, all the wiring diagrams I've seen in LoS have it wired the way your instructions show, must be a Thai thing.

It's no problem to worry, get water wrong and you can see it, get gas wrong and you can smell it, get leccy wrong and you just die

Edited October 18, 2008 by Crossy