3-phase Design Quandry

[elkangorito]

I'm kinda slow sometimes. This thought just occured to me. The neutral conductor of the main feed cable has to carry the return current, right? If we are running a standard single phase, two conductor feed, that arrangement is pretty clear to me. But if we are running a "hybrid" 3-phase system driven by single phase, (as we have been discussing above), then it becomes not so clear to me. Specifically my question is this: if the three phase conductors are each 16 mm^2, then it seems strange to me that we can get away with the same size return (neutral) conductor. Shouldn't it be larger than the individual live conductors? Where has my thinking gone wrong?

Also, Elk, did you miss my question below?

Hi Zap.

You got me cold on that one. Thank heavens you noticed it. How embarrassing

Yes, the neutral will need to be upgraded to handle 100 amps. Without doing any calculations, I'd say a 50mm² copper cable of the same brand & type as the other cables, will be sufficient but I will do the calcs later tonight or tomorrow, just to be sure. I'm absolutely sure a 70mm² copper cable will be ok. I also recommend that the conduit size be a minimum 50mm.

I understand your conclusion and accept it. (I have already ordered the 30 amp breaker.) I am still trying to understand and learn however, so please indulge me for a moment. I presume that the 50 amp breaker would trip if the current exceeds 50 amps on any one of the three poles. Therefore, in order to reach 150 amps, wouldn't all three poles have to see 50 amps simultaneously? If this is so, I cannot picture the circumstances that would cause this to happen. Can you please give me an example(s)?

This could only happen if a fault occured. The nature of any fault may vary e.g. a fault with a relatively high impedance may cause a current to flow in excess of the equipment rating but not high enough to cause a fast trip. This kind of fault is typically handled by the thermal part of the circuit breaker.

A low impedance fault is more likely to be in the order of hundreds or thousands of amps, which would trip via the magnetic action of the circuit breaker (fast trip).

The chances of this kind of thing happening may be small but it only needs to happen once & you may then have a fire on your hands.

Edited November 25, 2009 by elkangorito

[InterestedObserver]

I'm kinda slow sometimes. This thought just occured to me. The neutral conductor of the main feed cable has to carry the return current, right? If we are running a standard single phase, two conductor feed, that arrangement is pretty clear to me. But if we are running a "hybrid" 3-phase system driven by single phase, (as we have been discussing above), then it becomes not so clear to me. Specifically my question is this: if the three phase conductors are each 16 mm^2, then it seems strange to me that we can get away with the same size return (neutral) conductor. Shouldn't it be larger than the individual live conductors? Where has my thinking gone wrong?

The neutral conductor in a 3-phase connection only has to carry the unbalanced load current. That's the reason for balancing the single phase loads when using a 3-phase connection. The phase currents at the neutral point will add, using phasors, to zero when the loads are properly balanced. The neutral conductor is also used to prevent the line to neutral load voltage from floating (fluctuating), but that is another subject.

Edited November 25, 2009 by InterestedObserver

[InterestedObserver]

The neutral conductor in a 3-phase connection only has to carry the unbalanced load current. That's the reason for balancing the single phase loads when using a 3-phase connection. The phase currents at the neutral point will add, using phasors, to zero when the loads are properly balanced. The neutral conductor is also used to prevent the line to neutral load voltage from floating (fluctuating), but that is another subject.

Sorry, I should have looked at the drawing in post #85. Although being called a 3-phase system the source is actually a single phase transformer. The neutral return will therefore have to be sized to carry the entire load current. My comments above are appropriate for a 3-phase system.

[david96]

For 3 phase config. 4 x16sqmm , for single phase config. parallel the cables 2 x16sqmm for the phase and 2 x16sqmm for the neutral.

Rating 3 phase 50A per phase, single phase 100A.

Prospective short circuit current (at the 3 phase 50kVA distribution transformer) 1500A (1.5kA). Transformer rating 220/380V. 75A per phase.

You could install a 32A, 40A or 50A 3pole MCB if using 3 phase config. 100A or perhaps an

80A for single phase config.

[elkangorito]

Zap.

I've done the calculations & you will need to upgrade the cable size from 4 x 16mm to 4 x 25mm in order to avoid a voltage drop in excess of 5% (5% of 220 = 11 volts).

This means that you will parallel 2 x 25mm cables for the active & 2 x 25mm cables for the neutral. These cables will provide more than ample current carrying capacity when you eventually go over to 3 phase, with even less voltage drop at times of high load.

With regard to the 3 pole Main Circuit Breaker, the "line side" (incoming side) poles will need to be linked together. This can be done with 2mm or 3mm flat copper busbar or looping each pole with a minimum 16mm cable (busbar is better). The Main Circuit Breaker still needs to be no larger than 30amps in order to provide some protection for the KWH meter.

Edited November 26, 2009 by elkangorito

[david96]

One would use a 3 pole MCB for 3 phase supply and a single pole MCB for a single phase supply. Eg, a 32A 3P or a 100A 1P.

Protection of the metering is the responsibility of the PEA, an HRC service fuse may be fitted on the line side of the metering. The MCB is the main switch. This would be on the load side of the metering.

The MCB has to trip at 1.45In ( a sustained overload ) and trip on fault current in less than 0.4secs. (AS3000). The current winding of an energy meter is very conservatively rated.

In in this case is the rating of the MCB.

The use of a MCB on the consumers mains complies with AS3000. clause 2.2.2 (d) Limitation. " The max. demand may be determined by the current rating of a fixed setting circuit breaker, or by the load setting of an adjustable circuit breaker."

Just for interest time to trip on 1.45In, approx 1 min as a guide. The higher the current the faster the tripping time.

Edited November 26, 2009 by david96

[elkangorito]

To uncomplicate matters, a single pole CB to suit this particular application & distribution board is the EZD100H1100, which is rated at 100 amps & has an interrupt capacity of 25kA (far too large) - 2840 Baht (list price). I will also wager that a conversion kit will be needed in order to install this single pole breaker instead of a 3 pole breaker in this DB since the location of this CB is NOT on the main chassis. The amount of time & cost in buggerising around with a single pole CB far outweighs the time & cost to simply install a 30 amp 10kA 3 pole CB EZD100F3030 - 2940 Baht (list price).

Meter protection is ultimately the responsibility of the PEA. I have never seen HRC fuses (installed by the energy authority) used to protect KWH meters in Thailand. Nonetheless, if problems occur with the meter, it means inconvenience & a possible argument with the energy authority. In order to reduce the chance of meter problems & arguments, limiting the current through the meter can be done at the main DB (30 amp 3 pole CB). This, of course, excludes any faults that may occur in the consumer mains.

Many of the domestic installations in Thailand have "unprotected" consumer mains according to AS3000:2007. This particularly applies to consumer mains that are in underground conduit. Notwithstanding this, I have seen many DIN HRC fuses mounted on the secondary side of the distribution transformers (in Thailand). As a general rule, DIN type fuses will only provide adequate short circuit protection if they are no larger than 160 amps (max fault current - less than 10kA). Since I don't know the exact type of DIN fuses used, I'll assume that the consumer mains are "unprotected".

If one wishes to absolutely comply with AS3000:2007, all underground consumer mains in Thailand must be double insulated. In this situation, short circuit protection is not required but overload protection is required. Overload protection may then be placed at the entry to the consumer unit (DB).

The CB's used in this installation have different time/current characteristics than the "guide" in AS3000:2007.

May we now go back to where we were?

Edited November 27, 2009 by elkangorito

[david96]

Elk.

One was using AS3000 as a guide only to protection. Yes, most residential consumer mains are unprotected in Thailand. One does not have to comply literally with AS3000.

Yes, consumers mains (pvc/pvc in HD conduit or equiv.) do not have to be provided with short circuit protection as long as they are installed in "accordance with the additional requirements of the electricity distributor."

And there is no defined demarcation point between the PEA and the consumer, the nearest would be that the consumers responsibility commences after the load side of the energy metering. The metering and all on the line side is the responsibility of the PEA.

Some may differ on that definition.

And some protection is better than none at all on consumers mains. Minimise the risk.

I have not seen a 30A circuit breaker used since the early 1970s. It must be a US pattern.

And that is another problem with Thailand , mixing US with IEC/ AS standards. But that is another issue not applicable here.

My choice would have been 6kA MCBs. Terasaki or Heinmann CF, or 6kA DIN rail MCBs. with an 100A HRC service fuse connected on the line side of the meter, and mounted in an enclosure adjacent to the meter. One service fuse per phase.

[elkangorito]

Zap, can you provide an update please? Where are you at in your project?

[zapatero]

Zap, can you provide an update please? Where are you at in your project?

Sorry for the delay folks -- just returned from another medical trip.

I see that great minds have been at work here! It gives me a small amount of comfort, (not a lot, but at least a small amount), to see that knowledgeable experts can have different but well-argued opinions on the solutions to this project. It helps me to understand why I have had so much difficulty trying to surround this task when I myself lack the proper background. What is troubling though, is to think of all those poor blokes out there, in similar shoes as mine, who are facing these same kinds of questions; but haven't my determination to do it right, or even my limited knowledge to even attempt to do it right. I guess, bottom line, is that I am surprised that there are not more domestic electrical problems in Thailand.

To respond to your question, Elk, I plan to order 25 mm^2 cable*, and have already ordered the EZD100F3030 MCB, (compatible with my Square D DB, for anyone curious), as you have recommended.

I note that this MCB is a 10kA model. The electrical shop chap recommended that I go with the 30kA model, but I stood firm. However, (I'm still trying to learn), can you please tell me the implications that could have resulted if I had gone with his 30kA?

*(When I reach that point, I will parallel the two lives and two neutrals as recommended.)

[zapatero]

Prospective short circuit current (at the 3 phase 50kVA distribution transformer) 1500A (1.5kA).

David, can you please explain how you arrived at this 1.5kA? (I'm not being critical, only trying to understand.)

The MCB has to trip at 1.45ln ( a sustained overload ) and trip on fault current in less than 0.4secs.

...

Just for interest time to trip on 1.45ln, approx 1 min as a guide.

Also, could you please define "ln"? I've seen it many places now, but can't find a definition.

My choice would have been 6kA MCBs. Terasaki or Heinmann CF, or 6kA DIN rail MCBs.

I am interested to know your choices; however, I have already purchased my Square D load center (DB), MCBs, RCBOs, etc., so must remain compatible with them. My choices are pretty limited now.

Thanks again,

~~z

[stgrhe]

I am interested to know your choices; however, I have already purchased my Square D load center (DB), MCBs, RCBOs, etc., so must remain compatible with them. My choices are pretty limited now.

Nothing stops you from housing your main circuit breaker outside the Square D load center. Should you wish to add HRF/HRC fuses they could easily be fitted inside the same housing as the main circuit breaker. Hence, do not let your current load center limit you choice.

[david96]

Prospective short circuit current (at the 3 phase 50kVA distribution transformer) 1500A (1.5kA).

David, can you please explain how you arrived at this 1.5kA? (I'm not being critical, only trying to understand.)

The MCB has to trip at 1.45ln ( a sustained overload ) and trip on fault current in less than 0.4secs.

...

Just for interest time to trip on 1.45ln, approx 1 min as a guide.

Also, could you please define "ln"? I've seen it many places now, but can't find a definition.

My choice would have been 6kA MCBs. Terasaki or Heinmann CF, or 6kA DIN rail MCBs.

I am interested to know your choices; however, I have already purchased my Square D load center (DB), MCBs, RCBOs, etc., so must remain compatible with them. My choices are pretty limited now.

Thanks again,

~~z

1. Prospective Short Circuit current.

This is calculated at the distribution transformer terminals if jointed together as in a short circuit of effectively zero ohms at the fault.

A typical transformer has an impedance Z of about 5%. This means that only 5% of the normal line volts on the HV side will give full load current in this case 75A. for a 50kVA transformer. Therefore 100% will be 20 x 75A = 1500A (1.5kA)

Depending on the size of conductors from the transformer the fault current at the point where your consumers mains connect to the PEA ( eg meter) this value would be considerably less if you had an equivalant fault at this point.

A 200kVA transformer would be about 6kA. This is why a CB must clear a fault quickly without destroying itself. Sustained fault currents cause high temperatures, damage to equipment, arcing etc.

If the PSC fault level were 15kA at a switchboard and a 6kA MCB were used this MCB could not carry the fault current. One would have two options, replace the MCB with one exceeding 15KA or fit fault current limiters, in other words HRC fuses. the second option is generally the preferred one in practice.

(Most MCBs for general residential installations are rated at 3 to 6 kA)

( Have a look at the effects of 100A from an electric welder re arcing)

2. In is the continuous rating of the MCB in amps. eg 20A.

3. The choice of MCBs, no particular reason, generally what is readily available. Square D seems to have a monopoly in Thailand. Square D is now Schneider. Here is the Thai website see the Multi 9 range of DIN MCBs for your information (Terasaki is an option. They are of Japanese manufacture.) Terasaki are generally more expensive for some reason.

http://www.schneider-electric.co.th/sites/...function_id=108

[david96]

Hi Zap.

Here is a drawing that might clear up some technical points.

[elkangorito]

Typical 250KVA transformer impedances range from 3% to 7%.

If an "average" of 5% is assumed for a 250KVA transformer, the Prospective Fault Current at the transformer terminals will be;

1] transformer full load current = 250000/(1.732 x 380) = 380 amps.

2] transformer prospective fault current = 380 amps/0.05 = 7600 amps (7.6kA).

Since your supply transformer size is unknown & can be up to about 250KVA (as I have seen in Thailand) & also the transformer impedance may vary (according to manufacturer & requirements), it is prudent to assume a maximum Prospective Fault Current of 10kA. This will cover ALL possible situations.

For a 250KVA transformer with a 3% impedance, the Prospective Fault Current would be about 12700 amps (12.7kA).

The size, length & configuration (Trefoil etc) of the load side conductors will reduce this Prospective Fault Current but to what degree? This can be calculated.

This is why I chose a 10kA Main Circiut Breaker for you. There are simply too many unknowns & cost cutting (equipment size/capacity reduction) will be inconvenient & quite possibly dangerous.

Also, using your currently selected system of breakers, "cascading" is effective. If you want to know what this is, ask & I'm sure you will be answered. Cascading is not essential or required by your installation but again, the size of your distribution transformer is unknown. This "cascading" ensures that your installation is safe. Circuit breaker "Cascading" can only be done with circuit breakers of the same brand & only if the manufacturer indicates this as such. The manufacturer will usually specify the types & sizes of circuit breakers that can be cascaded with other circuit breakers.

Again, if the PEA would install BS88 HRC fuses (good) or BS1361 HRC fuses (better), Prospective Fault Current would never be a problem.

Unfortunately, you may not be able to control what the PEA installs. They do not seem to care about the protection of consumer mains or KWH meters.

[zapatero]

stgrhe:

I was under the impression that the HRC fuse needed to be installed upstream from the PEA meter -- please correct me if I am wrong.

david96:

Thank you for answering my questions and for your extended explanations. I think I am actually beginning to understand more of this.

And thank you for the diagram. Way back when this tread was started, (probably so long ago that normal people would have forgotten), I noted that I began with the Crossy/Elk "House Wiring Page", [http://www.crossy.co.uk/wiring/]. This is a very excellent starting point and I learned a lot from it. I would recommed it to anyone who finds himself in similar circumstances to my own. Anyway, your chart is consistent with their chart, [http://www.crossy.co.uk/wiring/CU-2.jpg] from that site.

Re "Multi 9 range of DIN MCBs", at Elk's suggestion I had looked at these way back in the beginning, but I have since been under the impression that DIN-rail mounting is not compatible with my Square D load center.

Elk:

Thank you for the calculations and explanations. This is making more sense now. I think you may have gotten the wrong impression though, that I am seeking "cost cutting" approaches. Not so. Only trying to learn and understand.

... and have already ordered the EZD100F3030 MCB, ... , as you have recommended.

I note that this MCB is a 10kA model. The electrical shop chap recommended that I go with the 30kA model, but I stood firm. However, (I'm still trying to learn), can you please tell me the implications that could have resulted if I had gone with his 30kA?

I am still not clear though about my above question. Would the only consequence be that I would be paying for additional robustness that would be unnecessary?

Re "cascading", yes, I think I understand the concept. I am hoping that I won't have to go down that road, yet, as it will mean more time and research.

Re the HRC fuses, it would certainly be comforting if I could rely upon the PEA to properly take care of this. I would even be happy to pay for it. But I don't even know how to introduce the subject. If I write down "BSC xxxx HRC fuse" on a piece of paper, (in English), and show it to them, they most likely won't even know what I'm talking about. And can you imagine my success at translating High Rupture Capacity into Thai?

Have you, or anybody, had any luck mixing PEA with HRC? And, if so, how did you go about it?

[stgrhe]

stgrhe:

I was under the impression that the HRC fuse needed to be installed upstream from the PEA meter -- please correct me if I am wrong.

That is probably how they are normally installed but what is stopping you to add them on "your side" of the meter if you like to have them?

[elkangorito]

Hi Zap. My comments in blue.

Elk:

Thank you for the calculations and explanations. This is making more sense now. I think you may have gotten the wrong impression though, that I am seeking "cost cutting" approaches. Not so. Only trying to learn and understand.

My apologies. I wasn't suggesting that you were attempting to cut costs. I was merely suggesting that this could be an unwise cost cutting measure if the unknowns were not revealed.

I note that this MCB is a 10kA model. The electrical shop chap recommended that I go with the 30kA model, but I stood firm. However, (I'm still trying to learn), can you please tell me the implications that could have resulted if I had gone with his 30kA?

I am still not clear though about my above question. Would the only consequence be that I would be paying for additional robustness that would be unnecessary?

Zap, you are correct. The extra "robustness" of a 30kA CB for a domestic installation is unwarranted in your case. He's trying to make some extra bucks at your expense.

Re "cascading", yes, I think I understand the concept. I am hoping that I won't have to go down that road, yet, as it will mean more time and research.

Re the HRC fuses, it would certainly be comforting if I could rely upon the PEA to properly take care of this. I would even be happy to pay for it. But I don't even know how to introduce the subject. If I write down "BSC xxxx HRC fuse" on a piece of paper, (in English), and show it to them, they most likely won't even know what I'm talking about. And can you imagine my success at translating High Rupture Capacity into Thai?

Have you, or anybody, had any luck mixing PEA with HRC? And, if so, how did you go about it?

When the PEA/MEA decide to install HRC fuses with every installation, they will be enhancing the safety & performance of every client's electrical system.

The primary reasons for having HRC fuses BEFORE your KWH meter is to;

1] protect the KWH meter (overload protection - in the interest of customer service).

2] protect your consumer mains (fault current protection - in your interest).

3] reduce the cost of switchgear in domestic installations (in your interest).

Installation types can vary. If your installation has a guaranteed low Prospective Fault Current (less than 6kA), overload protection is still required. This can be an appropriately sized MCB in your consumer unit. Again, this is only for a guaranteed low Prospective Fault Current although your consumer mains should still be double insulated cables. I wouldn't worry about this too much unless your distribution transformer is large & very close to your connection (larger than 150kVA).

Since you PFC is unknown (but is likely to be low), the best you can do is to provide overload protection at your end (appropriately rated MCB). Your installation will be protected AFTER this MCB but your consumer mains may be damaged due to a high PFC. Example - a tree falling across your consumer mains & thereby creating a high current short. In this case, your KWH may be damaged or destroyed (you will pay) but your installation will be unharmed.

The placement of HRC fuses at your end of the installation (in your consumer unit) is a waste of time & money. If these fuses are to be used, they should be placed BEFORE the KWH meter.

[zapatero]

Abnormal for me -- I have run out of questions!

But I hate to just leave things hanging. I sincerely want to thank everyone who has contributed to this thread. But especially Elk, who has sheparded this project through from beginning to end. He has graciously spent many hours on my behalf, not only here but through PMs and emails. I shudder to think where the project would be now without all of his help. Thanks again, Elk!

This has been a real learning experience for me. I hope that other readers, who might find themselves in a similar situtation, may somehow find some benefit by following these laborously won posts.

With my project defined, and unless something new emerges, I will leave this thread for now -- but will report back when we "throw the switch".

Best regards, and thanks again,

~~z

[Crossy]

^^^ It was starting to turn into a "3-phase design saga"

Make sure you post pictures of the fireworks

Actually photos of the final installation would tie up the ends nicely.

[zapatero]

Good idea, Crossy -- thank you; I will do that.

~~z

[elkangorito]

Hi Zap.

How about an update

I hope all went well.

[zapatero]

Big apologies for the long delay, Elk, et. al. I have not been monitoring this thread, but was waiting until I had something to report.

It has been a long and stressful journey getting here, but finally we got our PEA meter connection. For the benefit of any newcomers to this thread who may be interested, and any oldcomers who have probably happily forgotten all of the previous exchanges, I will attempt to summarize how we got here, and then to describe the implementation that has resulted.

To begin, during the initial phases of a new home construction, I became increasingly aware that there were some very large gaps between 1) the meager switchgear specifications of our architect's plan, (all in Thai, of course), 2) a proper modern Western-class switchgear design, and 3) the expertise of our contractor's electrician to implement a proper design, given the absence of detailed specifications. In fact, my ET was asking me to provide him this design guidance! I had no experience in this area at all, knew of no one in my local community that had the capability to undertake this task, and in fact knew of no one with whom I could even consult. When I tried to discuss RCDs and GFCIs with the local experts, it became quickly clear that they didn't even know what I was talking about, much less how to incorporate these components into an integrated design. The best half-relevant response that I received was to buy a Saf-T-Cut -- the one that cuts power to your whole house if any single circuit has ground leakage. This was when, out of desperation, I posted my woes on ThaiVisa.

Fortunately, folks were sympathetic. Elk did an MD (Maximum Demand) calculation for me, resulting in 101 amps, which led to the conclusion that a 3-phase design would be appropriate. That led to the next hurdle, as 3-phase is not yet available at our site. Two choices. 1) Either pay PEA the costs to extend 3-phase service to our site, including cables, poles, transformers, etc.; or 2) to "tough it out" with a single phase solution until the PEA eventually brings 3-phase past our site. We chose the latter. All of the following discussion is consistent with that decision, and it is also consistent with the overall design that eventually evolved during the above five pages of postings.

The decision was made to go with Square D, (now Schneider), products because they seem to be the most popular in this region and this might simplify any future changes or repairs. A 30 pole QO3-100EZ30G/SN load center was chosen. 28 poles/sub-circuits have already been allocated, with 14 of these RCBO-protected. (Schneider chooses the term RCBO (Residual Current Breaker with Over-current protection) = RCD (Residual Current Device) + MCB (Miniature Circuit Breaker)).

For the interim single phase solution, an EZD100F3030 main breaker was chosen; with the reasoning that as a 30 amp breaker, by limiting the current flow it will help protect the PEA's 30/100 meter. (Please refer to the attached chart, which will help clarify this discussion.) At the time of conversion to 3 phase power supply, the intent is to then swap the main breaker to an EZD100F3050. This reasoning is based upon Elk's original argument that went something like this: MD = 101 = 34 amps/phase, rounded up = 40, then use 50 amps/phase for conservatism.

To reiterate from one of my previous posts, there are only three PEA meter sizes available in our area: 5/15, 15/45, and 30/100. The PEA still thinks that a 15/45 would do my job, but were willing to give me a 30/100, (for more money). FYI, the 30/100 single phase meter cost 12,383 THB, including installation and connection fees; of which I understand that 5000 THB can be redeemed when trading up to the 3-phase meter. I understand that the 3-phase 30/100 meter will cost 38,754 THB.

As to whether the available PEA supply amperage is actually adequate to supply an MD of 101 amps, as David96 previously noted, is dubious. I asked the PEA again, what is the size of our distribution transformer? This time they told me 30 KVA. The previous time a different person told me 50 KVA. Either way it seems questionable to me, but perhaps they are calculating that it will be adequate as long as we remain single phase(?) I don't know their thinking, but I guess it is really their problem now because I have told them our MD, and they have endorsed our solution.

As you will note from the attached chart, the mains cable is 4-core copper, 25 sq.mm per core. It is NYY grade insulation, 90 meters long, buried in PVC conduit. Also note on this chart, as was recommended in some of the above posts, that the four cores have been paralleled into only live and neutral conductors for this interim single phase configuration.

The system has been up and running in this interim configuration for several days now and appears to be functioning satisfactorily. I am attaching four photos for additional information.

A couple of further miscellaneous notes, if anyone is interested. Much discussion has been made in this thread, and in the Crossy/Elkangarito website, regarding HRC fuses. I have pressed the PEA reps on several occasions regarding this issue, trying to determine whether/if/where they are used. Last week, at my latest attempt, after bumbling through the translation barrier, (can you picture trying to translate "High Rupture Capacity" into Thai?), I was finally told that they have high-voltage fuses and low-voltage fuses already installed. "They are respectively 6000 amps and 60 amps, (er... or 600 amps(?))" At that point I could see that this conversation wasn't going to yield any satisfying answers. So I guess, finally, I give up. If anyone has any additional knowledge on the use of HRC fuses in Thailand, I would be interested to hear it.

And regarding SPDs, (Surge Protection Devices) for our installation, I simply ran out of time. I still intend to do more research, but if anyone has had good experience with specific make/models of SPDs, I would greatly appreciate your insights.

Finally, I would again like to thank everyone who has contributed to this thread, as it has been very valuable for me. And I would especially like to thank Elk for all the time and effort, (apparent in the above posts), that he has spent on my behalf.

I will be happy to answer any questions, or at least I will try to answer any questions.

~~zapatero

[stgrhe]

 

And regarding SPDs, (Surge Protection Devices) for our installation, I simply ran out of time. I still intend to do more research, but if anyone has had good experience with specific make/models of SPDs, I would greatly appreciate your insights.

I will let you know once my installation is up and running. I have chosen ABB products for my house with the exception for the surge protectors that are from Dehn.

http://www.dehn.co.uk/uk/welcome.shtml

ABB's main distributor here in Thailand, PMK, recommended me to chose Dehn's surge protectors rather than ABB's due to avalability. They also claim both companies products are equally good. We will see when that day comes.

[elkangorito]

Looks like a great job Zap

Would it be possible to provide me with the model number of the kWh meter please? I want to check something.

[zapatero]

Thanks for the vote Elk.

Attached is a close-up of the meter. Can you pick the model number out of this? It looks like maybe MF-33E. If not, please tell me where to look

Looks like a great job Zap

Would it be possible to provide me with the model number of the kWh meter please? I want to check something.

[elkangorito]

Thanks for the pic Zap. Everything's ok...I just wanted to varify the meter specs.