3-phase Design Quandry

[zapatero]

Hi Zap.

As usual, my comments in blue.

Elk:

From my POV, your rev_3 looks fine, except that the "RCCB – 20A. GPO's, kitchen" (Load Group C) is still on Phase C, instead of the original Phase A; which appears to overweight the balance onto Phase C....(?) Please tell me if I'm not understanding something.

Thank you very much,

~~z

[elkangorito]

Hi Zap.

Comments in blue.

I have found out a few things from Schneider/Square D that might be helpful to other people:

What's the difference between a Consumer Unit and Load Center? Ans: CU is single phase, LC is 3 phase.

This is only Square D's interpretation. It's certainly not true in Australia. Generally speaking, CU's & LC's are smaller than DB's, however, they are both types of DB's.

What's the difference between the "Visi Smart" and "Classic" designs? Ans: Mostly the paint! But the VS models have a curved front plate. He says most people still use the Classic

What's the difference between a "Main Breaker" and "Lug" model panel? Ans: The Lug model goes direct, without passing thru a main breaker.

I suggest you use the lug model. I will re-design the DB layout to reflect this, as well as the use of single pole space RCCB's (instead of 2 pole space RCCB's). I will have it ready later today.

To answer some of your questions, Elk:

The QO1xxvs6RCBO30 series RCBOs do occupy only one pole slot in the distribution panel, (not two)

Based upon what I have just learned (above), your suggested QO3-100L36G/SN panel is a "Main Lug" type Load Center.

I think now that their comparable QO3-100EZ36G/SN "Main Breaker" type Load Center might be appropriate -- what do you think? See my previous comment.

BTW, "EZ" refers to their EasyPact main breaker series; whereas, (I presume), "L" indicates Lug.

I am not clear yet on split Neutral bars -- I've asked for more details

I am O.K. on the earth stake now. Yes, indeed there is definitely a MEN system in our area. Even the PEA guy affirmed this (for which I give him some credit) and showed me his diagram. My ET, (sparky) has assured me that he intends to do full testing before power up. (Of course the word "full" is open to examination). But he is pretty conscientious, so I expect that he will do this as comprehensively as he knows how, (considering the TiT factor limitations.)

I think it's best to discuss the "testing" after we have sorted out all of the DB arrangements.

Regarding our present supply cables, we have none yet, so this is still an open issue. We do intend to run underground from the utility pole though, so I presume, from your and Crossy's webdoc, that these cables will need to be derated.

A distance from the "service connection" (transformer/power lines) to your "Point Of Attachment" (where the service cables connect to your house) will be useful. It will allow me to calculate a cable size for you. You can use this to compare with the PEA's cable size.

Finally, a question, a comment, and more information:

Question: Has anyone attempted to extend the two diagrams in the "Distribution Board/Consumer Unit" section of the Crossy webdoc -- from single phase to three phase?

If so, that would surely help me to get my head around this thing that we are creating.

Comment: Some may find it amusing, (as I do rolleyes.gif ), that the Safe-T-Cut sales reps have visited our site three times now, trying to convince my ET and me that their product is the way we should go...

It is a very good idea to NOT mix brands of switchgear. I strongly suggest that you use one brand only. There are technical reasons for this, which I can explain if you wish.

More Information: I have just received more pages from the Square D catalogue, which I will attach to this post. These pages address MCBs, RCBOs, and SPDs; with more specifications and pictures.

Elk, the RCBO series that we have been discussing is shown. Note the cables coming out of the bottom, which he says are the "inputs".

Zap, I can't download this attachment (same problem as before). Could you please email it to me.

Elk:

From my POV, your rev_3 looks fine, except that the "RCCB – 20A. GPO's, kitchen" (Load Group C) is still on Phase C, instead of the original Phase A; which appears to overweight the balance onto Phase C....(?) Please tell me if I'm not understanding something.

It has always been on C phase. From "zapatero max demand calc and load balance - final.pdf",

All socket outlets should be RCD protected. I would divide the upstairs across 2 x 20 amp RCD's, both on B phase. I would divide the downstairs across 3 x 20 amp RCD's, all on C phase. 1 of these RCD's should supply the kitchen only. Your/fridge/freezer may be on a circuit NOT protected by an RCD if your fear

nuisance tripping.

Ok Zap, I'll have the revised DB layout ready later this afternoon. It shall reflect the following;

1] the addition of a Main Switch connected to the CB chassis (not separate as in the original layout).

2] single pole RCCB's instead of 2 pole RCCB's.

[elkangorito]

Zap.

Find attached "DB layout rev 4".

With this layout, you could reduce the size of your DB from 36 pole to 30 pole. A 30 pole DB would give you 6 spare spaces.

DB_layout_rev_4.pdf

[zapatero]

Hi Zap.

Comments in blue.

Hi Elk,

My comments in pink.

What's the difference between a Consumer Unit and Load Center? Ans: CU is single phase, LC is 3 phase.

This is only Square D's interpretation. It's certainly not true in Australia. Generally speaking, CU's & LC's are smaller than DB's, however, they are both types of DB's.

I wasn't trying to be global/comprehensive, only explaining Square D's labels. But I guess I'm not too surprised at this, with so many other names for some other things. e.g., GFCI, GFI, RCD, RCCB, RCBO,... I guess what matters is that you and I are using the same terms...

What's the difference between a "Main Breaker" and "Lug" model panel? Ans: The Lug model goes direct, without passing thru a main breaker.

I suggest you use the lug model. I will re-design the DB layout to reflect this, as well as the use of single pole space RCCB's (instead of 2 pole space RCCB's). I will have it ready later today.

Could you please amplify for me why we wish to use a Main Switch (and describe it), rather than a Main Breaker? This confuses me -- I would have thought the opposite.

I think it's best to discuss the "testing" after we have sorted out all of the DB arrangements. I agree.

A distance from the "service connection" (transformer/power lines) to your "Point Of Attachment" (where the service cables connect to your house) will be useful. It will allow me to calculate a cable size for you. You can use this to compare with the PEA's cable size.

Thank you -- I will work on this

Comment: Some may find it amusing, (as I do rolleyes.gif ), that the Safe-T-Cut sales reps have visited our site three times now, trying to convince my ET and me that their product is the way we should go...

It is a very good idea to NOT mix brands of switchgear. I strongly suggest that you use one brand only. There are technical reasons for this, which I can explain if you wish.

I only intended that comment as marketing amusement. No, I wouldn't consider mixing brands.

More Information: I have just received more pages from the Square D catalogue, which I will attach to this post. These pages address MCBs, RCBOs, and SPDs; with more specifications and pictures.

Elk, the RCBO series that we have been discussing is shown. Note the cables coming out of the bottom, which he says are the "inputs".

Zap, I can't download this attachment (same problem as before). Could you please email it to me.

It's on the way

Elk:

From my POV, your rev_3 looks fine, except that the "RCCB – 20A. GPO's, kitchen" (Load Group C) is still on Phase C, instead of the original Phase A; which appears to overweight the balance onto Phase C....(?) Please tell me if I'm not understanding something.

It has always been on C phase. From "zapatero max demand calc and load balance - final.pdf",

All socket outlets should be RCD protected. I would divide the upstairs across 2 x 20 amp RCD's, both on B phase. I would divide the downstairs across 3 x 20 amp RCD's, all on C phase. 1 of these RCD's should supply the kitchen only. Your/fridge/freezer may be on a circuit NOT protected by an RCD if your fear

nuisance tripping.

I think I'm confusing something about the "Load Group C" from the MD document. It was on Phase A, (unless I have missed an update). But let's press on and not take any more of your time on this point

Ok Zap, I'll have the revised DB layout ready later this afternoon. It shall reflect the following;

1] the addition of a Main Switch connected to the CB chassis (not separate as in the original layout).

2] single pole RCCB's instead of 2 pole RCCB's.

I'm sure you don't realize how much I appreciate all your effort!!

[elkangorito]

In answer to your question;

Could you please amplify for me why we wish to use a Main Switch (and describe it), rather than a Main Breaker? This confuses me -- I would have thought the opposite.

The words "Main Switch" describe a function of a switching device. The words "Main Breaker" describe both the function & the type of device used in that function.

Come to think of it, it wouldn't be a bad idea if your Main Switch was a CB. I say this because it's highly likely that you may not have any "upstream" protection for your supply cables (cables from the service connection to the Point Of Attachment).

[elkangorito]

Zap. I've just checked the info you sent to me by email.

The QOvs-RCBO is for a "plug on system". I'm not sure what this means.

If you choose the "classic" 100A 30 pole DB (without Main Switch), you had best make sure that the RCCB's & CB's are compatible with it.

Again, I have no idea what this "plug on system" is.

[zapatero]

Hi Elk,

My comments in pink

The words "Main Switch" describe a function of a switching device. The words "Main Breaker" describe both the function & the type of device used in that function.

Come to think of it, it wouldn't be a bad idea if your Main Switch was a CB. I say this because it's highly likely that you may not have any "upstream" protection for your supply cables (cables from the service connection to the Point Of Attachment).

Sorry, I'm still not clear about the difference. For "Main Switch" are we talking about a manual device? Perhaps a knife switch? If not, can you please tell me where I might look at one of these in, say, the Square D or Clipsal catalogues?

And second, are you suggesting that maybe we should be using a "Main Breaker" instead? I do agree with you that illusions of upstream protection are probably unwarranted.

Zap. I've just checked the info you sent to me by email.

The QOvs-RCBO is for a "plug on system". I'm not sure what this means.

If you choose the "classic" 100A 30 pole DB (without Main Switch), you had best make sure that the RCCB's & CB's are compatible with it.

Again, I have no idea what this "plug on system" is.

I've just emailed you some more new stuff from Schneider re Square D components, that I think should help answer your questions. If it does, and you think it might be useful to other folks, I will upload it to the forum also.

[zapatero]

Hi Elk,

My comments in pink

Sorry, I'm still not clear about the difference. For "Main Switch" are we talking about a manual device? Perhaps a knife switch? If not, can you please tell me where I might look at one of these in, say, the Square D or Clipsal catalogues?

O.K., I think I have just answered one of my own dumb questions: I think an example of such a "Main Switch" is shown on p. 33 of Elk's previously referenced Clipsal catalogue -- called a "Power Range Isolating Switch". (Someone please correct me if I'm wrong.) Thus it is indeed a manual switch. So now I guess I am still confused as to why we would not prefer a breaker switch for this function. (?)

[zapatero]

Elkangorito has indicated to me that he is taking a break from Thai Visa. So sadly, this thread will henceforth be absent his valued contributions.

For the benefit of any readers that may be interested, I will summarize the issues and latest conclusions thus far. If this generates some controversy and second opinions, that is fine with Elk, and will be welcomed by me -- I'm still learning.

The MCBs will be QO1xxvsC6T, where xx is the current rating. These are shown on p.6 of Ref.4, and p.12 of Ref.5.

The RCBOs will be QO1xxvs6RCBO30, where xx is the current rating. These are shown on p.6 of Ref.4, and p.14 of Ref.5. These RCBOs occupy only one pole slot on the DB(Load Center). Both Elk and Schneider/Square D concur on these choices of MCBs and RCBOs.

The Schneider folks insist that a split-neutral in the DB is not required for installation of these RCBOs; however they do require a peculiar installation with additional pigtails, as different from the MCBs. (See Refs. 7, 8 & 11 below.)

Elk has recommended the 30 pole QO3-100L30G/SN "Main Lug" type DB, as shown on p.8 of Ref 4; with a 50 Amp Main Switch/Main Circuit Breaker QO350vsC10T, as shown on p.6 of Ref.4.

For sake of completeness, Schneider has recommended a "Main Breaker" Load Center model, with "EasyPact" Breaker. These are shown on p.9 of Ref 4. The models comparable to Elk's recommendation would be, Q03-100EZ30G/SN and EZD100H3050.

The differences between these choices have not been fully scrubbed yet, so this issue remains open. As Elk notes, the most important point is that all of selected components must be compatible. But he also thinks the Schnieder recommendation might be more expensive. (Again not yet determined.)

Finally, Schneider has also recommended a "QO-CON1PH" option to convert the load center from 3-phase to single-phase for the near-term interim. I do not have an attachment to show this thing, but if someone is interested, PM me and I can send you an email that does show it.

And really finally, Ref.3, Elk's Clipsal catalogue has lot of information in it, which I myself have still not digested -- but I recommend it.

References:

1) Elk's Maximum Demand Estimation doc, attached by Crossy on Post #4

2) Elk's Maximum Demand & Phase Balance Calculations, attached by him on Post #7

3) Clipsal Catalogue, link from Elk on Post #20

4) Square D Catalogue, pp. 1-10, attached by me on Posts #21, 26

5) Square D Catalogue, pp. 11-10, attached by me on Post #30

6) Elk's Distribution Board (DB) Layout, Rev 4, attached by him on Post #33

7) QOvsRCBO Instruction Sheet, attached below.

8) QOvsRCBO User Manual, attached below. (I don't see much difference, but here it is anyway)

9) QOvs dimensions, attached below.

10) Load Center front instruction sheet, attached below

11) Load center wiring with RCBO, attached below

Again, I would welcome any comments, thoughts, opinions as I'm still learning. This experience has been somewhat like drinking martinis out of a firehose.

~~z

QOvsRCBO_instruction_sheet.pdf

QOvsRCBO_User_manual.pdf

QOvs_dimensions.pdf

Load_Center_front_instruction_sheet.pdf

Load_center_wiring_with_RCBO.pdf

[elkangorito]

Hi Zap.

I'm back online.

[zapatero]

Glad you are back, Elk!

On your previous email you provided this clip for me:

From ASNZS3000:2007 (Australian Wiring Rules);

RCDs with a sensitivity of 30 mA are designed to operate before fibrillation of the heart occurs.

RCDs with a sensitivity of 10 mA are designed to operate before muscular contraction, or inability to let go occurs. Muscular contraction can result in inability to breathe. Infants may be more prone to this risk.

The use of a 10 mA RCD may be considered in areas of increased risk, such as circuits supplying outdoor equipment, bathrooms and areas such as kindergartens. However, the standing leakage from appliances may cause unwanted tripping of 10 mA RCDs and more circuits may be required.

This has me wondering whether the 30ma RCBOs are prudent, given that there will be a young one on the premises.

Some questions: Have you, (or anyone else reading this), ever been stung by 30ma? Just how bad is it? Would you recommend Square D's 10ma RCBOs instead? What has your experience been regarding their nuisance tripping?

Thank you very much,

~~z

[elkangorito]

No need to use 10mA RCBO's on the outside lighting circuit.

You probably could use 10mA RCBO's on the 2 upstairs GPO circuits & 2 of the downstairs GPO circuits, depending on what is plugged into the socket outlets. I wouldn't use one on the kitchen GPO circuit.

Remember, you have a very large number of socket outlets in your house - about 41 upstairs & about 76 downstairs. If you use 10mA RCBO's, you may need to divide these GPO's across even more circuits to avoid any nuisance tripping. This means that you will use up some of the spare spaces in your DB (you currently have 6 spare spaces).

Usually, only old equipment causes nuisance tripping. In any case, if electrical equipment causes an RCBO to operate, it pays to have the equipment checked...usually by an insulation resistance test. On many occasions, the equipment needs to be repaired or replaced. There is a minimum safe insulation resistance for electrical equipment, which is 1 million Ohms. Any less than this & the equipment is considered dangerous. The exception is some types heating equipment, which naturally has a low insulation resistance.

The average adult will not even know that they have had 30mA temporarily passing through their body because the RCBO operates very quickly (usually within 20mS, or one cycle). You wouldn't feel a thing. I certainly haven't felt anything although I have heard the "click" of the RCBO opening.

[zapatero]

No need to use 10mA RCBO's on the outside lighting circuit.

You probably could use 10mA RCBO's on the 2 upstairs GPO circuits & 2 of the downstairs GPO circuits, depending on what is plugged into the socket outlets. I wouldn't use one on the kitchen GPO circuit.

Remember, you have a very large number of socket outlets in your house - about 41 upstairs & about 76 downstairs. If you use 10mA RCBO's, you may need to divide these GPO's across even more circuits to avoid any nuisance tripping. This means that you will use up some of the spare spaces in your DB (you currently have 6 spare spaces).

Usually, only old equipment causes nuisance tripping. In any case, if electrical equipment causes an RCBO to operate, it pays to have the equipment checked...usually by an insulation resistance test. On many occasions, the equipment needs to be repaired or replaced. There is a minimum safe insulation resistance for electrical equipment, which is 1 million Ohms. Any less than this & the equipment is considered dangerous. The exception is some types heating equipment, which naturally has a low insulation resistance.

The average adult will not even know that they have had 30mA temporarily passing through their body because the RCBO operates very quickly (usually within 20mS, or one cycle). You wouldn't feel a thing. I certainly haven't felt anything although I have heard the "click" of the RCBO opening.

Well, of course, dummy! I was focusing on "are designed to operate before muscular contraction, or inability to let go occurs" But if I, (or the young one), can "let go" after 20mS, I think that will be acceptable. (Fast operation -- that's what RCBOs are for, aren't they?) In fact, I think I'm ready to accept 20ms of fillibration, given that this would be about 1/50 of a heartbeat. Your last paragraph satisfies me.

Yes, I know, someone will now say that 20ms is enough to trigger fillibration. Well, O.K., I guess I have to do some more research...

(But meanwhile I'm still going to think some more about your other well made points)

[zapatero]

Hi Elk,

In one of your last emails to me, you made the following recommendations -- to which I replied that I would report back:

To simplify matters, let the PEA do what they want. If "their" KWH meter gets damaged, it will not be your fault providing:

1] you let the PEA know of your MD (allow a minimum of 40 amps per phase...50 amps is better).

2] you size the supply cable (consumer mains) to accommodate 50 amps per phase.

3] you install the Main Circuit Breaker as advised (by me) - 3 pole 50 amps @ 10kA.

4] your KWH meter can handle 50 amps per phase.

and

5] You really need to tell the PEA about your MD BEFORE any cable goes into the ground. Can you imagine the hassle if undersized cable is installed (voltage drops & equipment failure)?

I have met with the PEA and filled out their required form so they will now "conduct a survey" to determine the costs of extending 3-phase power to our site, and alternatively, the costs of a transformer.

At the same time, as you have suggested, I advised them of the above points and asked for their guidance/recommendations re the supply cable. (I further noted that the distance from their pole to my load center would be about 100 meters, with about 80 of that underground.)

The chap's response was, "16 mm^2 (copper) should be just fine, but if you are concerned then you could use 25 mm^2".

Well, I was hoping for an answer with a bit more precision. To his credit, however, he copied a table for me so that I might better assure myself. Since it was all in Thai, I told him that I would take it home for study. After a few minutes of examination though, my ET observed that this table was for 350-700 volts, and that it nowhere included a distance parameter. So thus, from my POV, useless. And, in summary, I'm not feeling much better assured. That pretty much covers the cable specification progress, to date. Apologies if I haven't concealed my frustration very well.

Changing direction a little, we have just purchased the A/C units. To my surprise, (and with a bit more precision), I note from the specification sheets that the "Running Current" of the three models in question is only 3.59, 5.17, and 7.33 amps. Since these units will all be hard-wired, I am wondering if there might be the possibility of a little relief from our high MD result of 101 amps(?) If that might be possible, then might not there be the possibility of cost reductions in the cable ratings, the KWH meter tariff, and maybe even the main circuit breaker? (As you know, the costs of those first two are pretty dear.) If any cost savings would only be marginal, I can accept that. I'm just wondering if the thought is worth considering...(?)

Thank you very much,

~~z

[david96]

In Australia instantaneous water heaters of this size would not be permitted for obvious reasons.

We would install a storage HWS 270litre (60 gallon) with a heating element of 3600 watts

and connect it to an off peak tarriff.

However off peak tarriffs are not available in Thailand so one could connect it though a

time switch and set it to operate at night say between 10pm and 6am.

You could also heat the water using solar collectors and your element would be for boost

purposes only. Loading 15amps or a smaller element. Water temp should be 70C.

Shower (instantaneous) heaters should be limited to 10 amps single phase connection.

Do you really need all those socket outlets? A twin outlet is regarded as a single as far as

max demand goes.

Certainly a circuit breaker should be installed in lieu of a switch as it is unlikely that the supply authority has installed an HRC fuse for protection of the metering and consumers mains, this is common in Thailand.

It would appear that the supply authority require you to have your main switchboard connected to a 3 phase 4 wire supply.

This is different to Australia where the policy is to connect to single phase, 16sqmm, 10/80A

meter and 100A protection for consumers mains and metering as standard. Loading is balanced one residence to A phase and the next to B phase etc. Main switch is generally 80A.

Remember your MD as calculated and your actual load in amps at any give period of the day is not the same and will be considerably less.

Remember up to 50% of your energy requirements in KWH is consumed by airconditioning.

Household appliances 6%, electric hot water systems 12%, refrigeration 20%, lighting 2%, and entertainment (TVs VCRs etc) 10%. (source Ergon Energy Qld. Australia.)

[zapatero]

Hi David96,

Thank you for your reply.

Whoops -- I think I have unintentionally misled you. By A/C, I meant Air Conditioning! Hopefully my post makes more sense now(?)

In Australia instantaneous water heaters of this size would not be permitted for obvious reasons.

We would install a storage HWS 270litre (60 gallon) with a heating element of 3600 watts

and connect it to an off peak tarriff.

However off peak tarriffs are not available in Thailand so one could connect it though a

time switch and set it to operate at night say between 10pm and 6am.

You could also heat the water using solar collectors and your element would be for boost

purposes only. Loading 15amps or a smaller element. Water temp should be 70C.

Shower (instantaneous) heaters should be limited to 10 amps single phase connection.

Do you really need all those socket outlets? A twin outlet is regarded as a single as far as

max demand goes. Actually, almost all of them are doubles (twins, if I have your nomenclature correct). But I believe that Elk counts them as double. (Correct me if I am wrong, Elk)

Certainly a circuit breaker should be installed in lieu of a switch as it is unlikely that the supply authority has installed an HRC fuse for protection of the metering and consumers mains, this is common in Thailand. Indeed, this is our intent

It would appear that the supply authority require you to have your main switchboard connected to a 3 phase 4 wire supply. Ah! There's the crux of the matter -- 3-phase is not yet available at our site. So I had decided to "tough it out" with single phase until it becomes available. But I thought it practical to at least determine the costs of (read: paying for) extending 3-phase to our site.

This is different to Australia where the policy is to connect to single phase, 16sqmm, 10/80A

meter and 100A protection for consumers mains and metering as standard. Loading is balanced one residence to A phase and the next to B phase etc. Main switch is generally 80A.

Remember your MD as calculated and your actual load in amps at any give period of the day is not the same and will be considerably less. Check -- I understand

Remember up to 50% of your energy requirements in KWH is consumed by airconditioning. Right on! This was exactly the reason for my post. (Maybe I have made more sense now that I have corrected my ambiguity(?)) To be precise, I am wondering if perhaps we may have attributed more A/C weight to the MD than is actually appropriate, given those unexpectedly small amperages ... (?) And then, if indeed we have made the MD too large, perhaps we have the opportunity to save some costs by reducing it... (?)

Household appliances 6%, electric hot water systems 12%, refrigeration 20%, lighting 2%, and entertainment (TVs VCRs etc) 10%. (source Ergon Energy Qld. Australia.)

[elkangorito]

My comments in blue.

In Australia instantaneous water heaters of this size would not be permitted for obvious reasons.

Stiebel Australia doesn't agree with you.

http://www.stiebel.com.au/admin/pages/PDF/745983934.pdf

We would install a storage HWS 270litre (60 gallon) with a heating element of 3600 watts

and connect it to an off peak tarriff.

However off peak tarriffs are not available in Thailand so one could connect it though a

time switch and set it to operate at night say between 10pm and 6am.

You could also heat the water using solar collectors and your element would be for boost

purposes only. Loading 15amps or a smaller element. Water temp should be 70C.

This is by far an incredibly sensible & applicable solution for Thai residents. It astounds me that so many people are happy to throw away money & ruin the environment as opposed to installing a solar hot water system. A good quality system can last for at least 20 years without a problem. I recommend Solarhart or Rheem (copper). I do not recommend the Chinese glass tube units. Thailand is an ideal country for solar hot water systems. Also, you will not need a "booster" element in your solar hot water system. It doisn't get cold here...unless you're living in Chaing Mai.

Shower (instantaneous) heaters should be limited to 10 amps single phase connection.

That's pretty difficult unless you are happy with a lukewarm shower or a trickle of water

Do you really need all those socket outlets? A twin outlet is regarded as a single as far as

max demand goes.

Not according to ASNZS3000:2007 & ASNZS3000:2007 +Amendment 1. From the Standard;

TABLE C1 (domestic residense calculation).

Notes to Table C1.

h) For the purpose of determining maximum demand, a multiple combination socket-outlet shall be regarded as the same number of points as the number of integral socket-outlets in the combination.

Certainly a circuit breaker should be installed in lieu of a switch as it is unlikely that the supply authority has installed an HRC fuse for protection of the metering and consumers mains, this is common in Thailand.

It would appear that the supply authority require you to have your main switchboard connected to a 3 phase 4 wire supply.

This is different to Australia where the policy is to connect to single phase, 16sqmm, 10/80A

meter and 100A protection for consumers mains and metering as standard. Loading is balanced one residence to A phase and the next to B phase etc. Main switch is generally 80A.

Generally, this is true unless the MD calc for the residense proves otherwise. As a general rule, anything with an MD of 100 amps or over, warrants the use of 3 phase.

Remember your MD as calculated and your actual load in amps at any give period of the day is not the same and will be considerably less.

Remember up to 50% of your energy requirements in KWH is consumed by airconditioning.

Household appliances 6%, electric hot water systems 12%, refrigeration 20%, lighting 2%, and entertainment (TVs VCRs etc) 10%. (source Ergon Energy Qld. Australia.)

Hi David96,

Thank you for your reply.

Whoops -- I think I have unintentionally misled you. By A/C, I meant Air Conditioning! Hopefully my post makes more sense now(?)

In Australia instantaneous water heaters of this size would not be permitted for obvious reasons.

We would install a storage HWS 270litre (60 gallon) with a heating element of 3600 watts

and connect it to an off peak tarriff.

However off peak tarriffs are not available in Thailand so one could connect it though a

time switch and set it to operate at night say between 10pm and 6am.

You could also heat the water using solar collectors and your element would be for boost

purposes only. Loading 15amps or a smaller element. Water temp should be 70C.

Shower (instantaneous) heaters should be limited to 10 amps single phase connection.

Do you really need all those socket outlets? A twin outlet is regarded as a single as far as

max demand goes. Actually, almost all of them are doubles (twins, if I have your nomenclature correct). But I believe that Elk counts them as double. (Correct me if I am wrong, Elk)

I calculated your MD according to the current Standard. The Standard (both ASNZS3000:2007 & ASNZS3000:2007 +Amendment 1) say the following;

There are 4 ways to determine Maximum Demand from ASNZS3000:2007 & ASNZS3000:2007 +Amendment

1. They are as follows;

calculation, assessment, measurement or limitation.

TABLE C1 (domestic residense calculation).

Notes to Table C1.

h) For the purpose of determining maximum demand, a multiple combination socket-outlet shall be regarded as the same number of points as the number of integral socket-outlets in the combination.

i) Each item of permanently connected electrical equipment not exceeding 10 A may be included in load group B(i) as an additional point.

Certainly a circuit breaker should be installed in lieu of a switch as it is unlikely that the supply authority has installed an HRC fuse for protection of the metering and consumers mains, this is common in Thailand. Indeed, this is our intent

It would appear that the supply authority require you to have your main switchboard connected to a 3 phase 4 wire supply. Ah! There's the crux of the matter -- 3-phase is not yet available at our site. So I had decided to "tough it out" with single phase until it becomes available. But I thought it practical to at least determine the costs of (read: paying for) extending 3-phase to our site.

This is different to Australia where the policy is to connect to single phase, 16sqmm, 10/80A

meter and 100A protection for consumers mains and metering as standard. Loading is balanced one residence to A phase and the next to B phase etc. Main switch is generally 80A.

Remember your MD as calculated and your actual load in amps at any give period of the day is not the same and will be considerably less. Check -- I understand

Remember up to 50% of your energy requirements in KWH is consumed by airconditioning. Right on! This was exactly the reason for my post. (Maybe I have made more sense now that I have corrected my ambiguity(?)) To be precise, I am wondering if perhaps we may have attributed more A/C weight to the MD than is actually appropriate, given those unexpectedly small amperages ... (?) And then, if indeed we have made the MD too large, perhaps we have the opportunity to save some costs by reducing it... (?)

The A/C weight in your MD calculation is minimal. You will save 3 fifths of 5 eighths of nothing in the end (sorry). You A/C's were a part of the socket outlet calc as per;

i) Each item of permanently connected electrical equipment not exceeding 10 A may be included in load group B(i) as an additional point.

Household appliances 6%, electric hot water systems 12%, refrigeration 20%, lighting 2%, and entertainment (TVs VCRs etc) 10%. (source Ergon Energy Qld. Australia.)

[bangkokumpalumpa]

ok I havent read through your whole thread it was a bit to heavy for this time of night but I notice that you are looking at a 30 pole Square D load center.

we just happen to have one of those spare

if you are interested we have a second hand surface mounting Square D load center, its a 30 pole 100 A max

here is the cat number QO3-100EZ30G/S

it is fitted with a EZD100H 60A main breaker

all in very very nice condition

Now I know that these things dont come cheap so this might be a way to save a few notes.

let me know if you are interested

[elkangorito]

ok I havent read through your whole thread it was a bit to heavy for this time of night but I notice that you are looking at a 30 pole Square D load center.

we just happen to have one of those spare

if you are interested we have a second hand surface mounting Square D load center, its a 30 pole 100 A max

here is the cat number QO3-100EZ30G/S

it is fitted with a EZD100H 60A main breaker

all in very very nice condition

Now I know that these things dont come cheap so this might be a way to save a few notes.

let me know if you are interested

3 phase or single phase? Has it/they been used?

Edited October 29, 2009 by elkangorito

[bangkokumpalumpa]

3 phase

it has been used

also have a EZD100H 80A main breaker (3 phase) sitting in another load center, that one is a QO3-100EZ18G/S (18 pole)that load center is sitting is a large supply box with amp and volt meters.

its all in mint condition

just some of the things you collect in life

[david96]

One was looking at reducing the MD and the actual load for economic reasons and also have you considered the effect of all this loading on other consumers fed from the transformer?

An instantaneous HW unit(s) and a hotplate unit with perhaps two A/C units running?

The HW may be on for 5 mins but that is all extra load on the supply authority system.

In Qld, Australia, instantaneous HW units are not installed in residential instalations.

HWS are storage systems generally 45L to 270L with elements from 1.8 to 3.6kw.

They can be connected on "off peak" tariffs, depending on their watts/litre rating and switched

on and off as required by the supply authority though a relay on the customers main switchboard.

There was an instantaneous shower heater available over 25 years ago that consisted of a

shower head with a 10 A or 15A element, one had to turn the water on first then the power.

and they were very prone to burn out due to the fact that persons using the shower would turn off the water but forget to turn off the power. They went off the market in the end as

HWS became cheaper. It is policy to promote solar HWS ( with booster element available) in all new domestic installations now.

Instantaneous water heater systems are available but are used for commercial and industrial applications. Not in a domestic environment.

On the subject of socket outlets 20 twin x 10amp is ample for the average residence, runover 3 circuits two running through the "kitchen area"

Electric hotplate units, these could be replaced with LPG, thus reducing the MD.

We have to look at using energy more efficiently in the future and that means using load management combined with off peak use with favourable tarriffs.

But I am impressed with the shower heaters now available in Thailand but they do need good water pressure for them to work properly ie. the 10 A models only.

But I would doubt if they would meet the current approvals standards in Australia, they are well priced however.

Generally HWS are set to 70C and the smaller units for dishwashing etc are set to 82C.

[david96]

Just as a matter of interest do you know the size of your distribution transformer in KVA? Do you know the existing number of consumers fed from this distribution transformer at present?

[zapatero]

if you are interested we have a second hand surface mounting Square D load center, its a 30 pole 100 A max

here is the cat number QO3-100EZ30G/S

it is fitted with a EZD100H 60A main breaker

all in very very nice condition

Now I know that these things dont come cheap so this might be a way to save a few notes.

let me know if you are interested

Hi Bangkok,

Thank you for your kind offer, and PM.

Regrettably, my order has already been placed for everything, and it is scheduled for delivery.

I would be interested to know though, (and hope ), that you found these components to be satisfactory, as they are quite close to what I have ordered.

Thanks again.

~~z

[zapatero]

Hi David96,

You make some good points.

Unfortunately, the construction is already about 80% complete, including the wiring, so I am not at liberty to change very much. This whole thing has been a pretty stressful experience, and if I had the opportunity to do it over again there are a number of things that I would do differently. But right now, my goal is to get it over with, with as few more modifications to the design as possible.

Regarding the number of GPOs; you, (and Elk), are right -- I probably overdid it. But I've been in so many Thai houses that had too few GPOs, and then tripped over writhing octopuses of power strips, getting from one side of the room to the opposite. And also there are too many lights in the design. Many of these lights and GPOs will probably get very little use, but I suspect that they drove Elk's MD calculations up measureably.

Re your following questions:

Just as a matter of interest do you know the size of your distribution transformer in KVA? Do you know the existing number of consumers fed from this distribution transformer at present?

Sorry, I don't know either. And neither did the PEA chap. He will have to do his "survey" to determine what will be necessary to extend 3-phase to the property. What I do know is that he quoted 38,754 THB for a (30/100) 3-phase meter, but only 12,383 THB for a single-phase (30/100) meter.

[david96]

It will be interesting to see what your actual load will be when your electrical installation is finally connected to supply, it should be well below the calculated MD.

That cost for energy metering would include meter and connection to supply, single phase

or three phase. Meters remains the property of the PEA.

Strange that the PEA does not know the size in KVA of the distribution transformer it is usually

stamped on the side of the transformer and can be read from the ground. 50KVA and 100KVA

are common sizes for distribution transformers.

It is obvious that from your MD you may have to go to a 3 phase supply. Otherwise it is 22kw all on one phase or balance 22kw over 3 phases. ie approx 7kw per phase.

And if the PEA transformer is found to be too small it would have to be upgraded.

[zapatero]

It will be interesting to see what your actual load will be when your electrical installation is finally connected to supply

I have been thinking the same thing. In several locations around here I have seen voltmeters and ammeters side-by-side in a panel next to the load center. This would seem to me to be a practical way to monitor actual consumption and voltage drops as they occur. I asked the Schneider/Square D folks if they sell such units. They don't. Do you or anyone else know if there is a standalone box that will do this, or does it have to be specially built?

I asked my ET why I couldn't just buy the two meters and have him install them. He said that there would be more to it than that, that there would be additional electronics involved that he wasn't qualified to take on. (He, IMHO, is a good electrician, but he is (self-confessed) not an electrical engineer.)

Any thoughts?

[stgrhe]

I have been thinking the same thing. In several locations around here I have seen voltmeters and ammeters side-by-side in a panel next to the load center. This would seem to me to be a practical way to monitor actual consumption and voltage drops as they occur. I asked the Schneider/Square D folks if they sell such units. They don't. Do you or anyone else know if there is a standalone box that will do this, or does it have to be specially built?

I believe ABB have them but I suppose they are for DIN-rail mounting. Look at the their catalogue for the pro M compact series (Jan 2009) (pdf) here: http://www.abb.co.th/search.aspx?q=pro%20M%20compact

[bangkokumpalumpa]

I have a second hand one here, it is designed for three phase, you can switch the meters to different phases to view the volts and amps. it also has three lights that show that the three phases are working.

it has been set up to take a 30 pole Square D load center in it. I will take a pic and post it soon for you, and your sparky is right there is some extra wiring in there that allows for the switching and loads. will post pics of that too for you

[bangkokumpalumpa]

here are the pics of the cabinate and the meters, if you are interested in buying second hand then give me a PM

[zapatero]

I believe ABB have them but I suppose they are for DIN-rail mounting. Look at the their catalogue for the pro M compact series (Jan 2009) (pdf) here: http://www.abb.co.th/search.aspx?q=pro%20M%20compact

Thank you stgrhe. I tried but couldn't get it to download, but will try again tomorrow.

I have a second hand one here, it is designed for three phase, your sparky is right there is some extra wiring in there that allows for the switching and loads. will post pics of that too for you

here are the pics of the cabinate and the meters, if you are interested in buying second hand then give me a PM

Thank you bangkok. I may be interested. However this stuff is all new territory for me. I'm trying to get my head around all of it. I presume the center picture is the back of the first picture. But the right-hand picture -- what is it's function and where is it located? And what are all of the dimensions?

But secondly -- the obvious question, presuming that it all works well, why are you not using it?