Electrical design guidance on a new home.

[Aguda]

I will be meeting with the builder in a week for planning out the layout of the electrical service for our two story 234 sq. meter  4 bedroom 3 bath home. The contributors to this electrical forum always have a wealth of good advice so I would like to avail myself of your good natures. The home will be occupied by myself, my spouse, two children and her parents in Chiang Mai. My electrical knowledge is basic (enough for minor repairs without killing myself), and I want to attempt to get things right before the build. The standard 15/45 amp service appears to be adequate for our needs.  We currently do not use AC but I plan to pre wire for AC if we feel the need in the future. I will want power for the carport and sala, but just for lights and a GFCI outlet for each. Of course will have a RCBO breaker box with proper grounding on all circuits.  Are there any guidelines for minimum outlets per meter of wall and lighting  per meter of ceiling ? Is there anything any of you wish you designed in at this stage but overlooked? Any suggestions would be greatly appreciated!

[bankruatsteve]

The USNEC specifies that no point on a wall space should be farther than 6' from an outlet (that's maximum).  It helps to give it some thought - like on either side of where a bed will be.  Two duplex where TV etc. will be.  Two circuits of outlets to the kitchen (I have 4 duplex on either side of my kitchen).  More outlets the better such that you would never have to use those terrible extensions.

 

Effective lighting can get tricky but usually best to group or cluster such that you can go with 1-2 lights or say 10 on separate switches (using the number of lights instead of dimmer).  Recessed lighting is most common.  What the US calls a 3-way switch (on/off from two separate locations) seems to befuddle Thai sparks but insist on using them where needed (like bottom/top of stairs).  Forget trying to put in a "4-way" switch - they just aren't available here.

 

Separate circuits for A/C, heaters, pumps, what else?  You don't need GFCI outlet if already front-end protected with RCBO.

 

Basically, just imagine the stuff you have and where it will likely be placed and that should guide you to most of it.  

[Aguda]

Thank you for your reply  bankruatsteve! Definitely want to avoid extension cords whenever possible. Strange to say but have never lived in a home with recessed lights (which I plan to incorporate into the design). I would like to make them effective and not spaced too far apart. Never thought about the 3-way switch for the stairway, will add that to the design.

AC and water  pump will be on separate circuits. I was planning on 3 on demand hot water heaters, would they need a separate circuit each?

[bankruatsteve]

The thing about water heaters is that most will do just fine on 2.5mm2 - but NOT two or more.  If you really need to have two or more heaters on the same circuit you will need to increase wire size to 4mm2 or 6mm2.  Oh and if you will have an oven, that should be on separate circuit also.

 

Good luck with your builder.  Depending on electrical experience, they can be real stubborn about things they think are just "farang stupid".  I had one give me crap at needing more than one outlet per room (too expensive).  

[Aguda]

It sounds like you are saying if each of the bathrooms are on separate circuits I will be fine with combining lighting, outlets and water heater on the same circuit using 2.5 mm2 is that correct? While my builder wants to save on the cost of the home, he seems willing to build it to my specifications as long as my cash is paying the bill. The oven will be on a separate circuit also if installed. My wife wants one, but I don't see it getting much use.

[bankruatsteve]

7 minutes ago, Aguda said:

It sounds like you are saying if each of the bathrooms are on separate circuits I will be fine with combining lighting, outlets and water heater on the same circuit using 2.5 mm2 is that correct? While my builder wants to save on the cost of the home, he seems willing to build it to my specifications as long as my cash is paying the bill. The oven will be on a separate circuit also if installed. My wife wants one, but I don't see it getting much use.

Sure, that would work.  If you or your wife don't have specific requirement for an oven (like for pastries, pies, bread, casserole, etc.) you're probably better off with a decent sized counter-top convection oven.  Ovens are a big waste of money and space hog if they don't get used.

[Crossy]

Personally I would do something like:-

 

A separate circuit for each aircon position, 2.5mm² cable on a 20A breaker.

 

A separate circuit for each water heater, if your heater is <4.5kW and you have no intention of upgrading then 2.5mm² on a 20A breaker is OK. Personally I would use 4mm² on a 30A in case you want a bigger heater in future. Note, you should not really put a Thai outlet on a breaker bigger than 20A but in reality nobody is going to be plugging the welder in in the bathroom (are they?) so overloads are unlikely. Whatever you do this circuit must be RCD protected.

 

Two 20A outlet circuits for your kitchen (plus a couple of non-RCD outlets for the freezer).

 

One outlet circuit for two bedrooms.

 

One outlet circuit for the downstairs in addition to the kitchen ones.

 

A couple of lighting circuits, 1.5mm² on 10A breakers.

 

Keep outside outlets and lighting on their own RCD protected circuits.

 

Pool on it's own circuit with a 10mA RCD.

 

ALSO

 

Consider if you will be needing a genset, if so organise for a transfer switch and any load shedding (water heaters, aircon) you may want to do.

 

Make sure you have room in the board for breakers for your solar.

 

AND

 

Look at surge suppression on the incoming supply and scattered around the installation.

 

ALSO

 

Under / over voltage protection is wise, long term under voltage can kill your appliances, better to have no power (or be on the genset) than frying your A/C, fridge, freezer etc etc.

[Aguda]

Thanks for the suggestions Crossy! We don't plan on having a pool and are not out in the country  and have a relatively stable power supply, so I don't feel the need for a backup generator. While I like the idea of solar, I don't feel it to be a cost effective solution yet.  Will plan on separate  4 mm2 30 amp circuits for the water heaters. It looks like I will need a 12 breaker box with some extra room for adding circuits? I don't know a lot about electrical but want to insure it is done right from the start.

[maxpower]

2 hours ago, bankruatsteve said:

Effective lighting can get tricky but usually best to group or cluster such that you can go with 1-2 lights or say 10 on separate switches (using the number of lights instead of dimmer).  Recessed lighting is most common.  What the US calls a 3-way switch (on/off from two separate locations) seems to befuddle Thai sparks but insist on using them where needed (like bottom/top of stairs).  Forget trying to put in a "4-way" switch - they just aren't available here.

Change over switching only confuses the Thai sparks who spend most of the working week mixing cement. 

For those wishing to switch a circuit from more than two locations. Intermediate switches are available from National, Bticino, Haco and maybe a few more

[Aguda]

Don't know that I will need to switch the lights from more than 2 places, will have to think about that. Thank you for your input manpower!

[Crossy]

4 hours ago, Aguda said:

and her parents in Chiang Mai.

Have you got space for a granny / grandad annex? I'm sure they would love a simple but independent home, just to have their own space (and let you have space too).

 

 

[maxpower]

14 minutes ago, Aguda said:

Don't know that I will need to switch the lights from more than 2 places, will have to think about that. Thank you for your input manpower!

I just corrected and pointed out that switches are available if required. Doubt you will need such complications :)

 

Follow Crossy with the separate circuit idea and all should be good. Avoid the "one circuit does all"  Thais love so much.

Now you are talking oven water heaters and future AC there might come a point where your supply size gets a little stretched. Just a thought.

[Crossy]

56 minutes ago, maxpower said:

Now you are talking oven water heaters and future AC there might come a point where your supply size gets a little stretched. Just a thought.

It's certainly a thought, but diversity is your friend.

 

Even in the UK the suppliers, despite installing 80A or 100A main fuses, reckon on 2kW per home on average.

 

We have a 3 bed, 3 bath home with a pool, koi pond and 5HP of irrigation on a 15/45. Even with everyone here we rarely get anywhere near 50A and our 50A, c-curve incomer has never opened on over current.

[Aguda]

1 hour ago, Crossy said:

Have you got space for a granny / grandad annex? I'm sure they would love a simple but independent home, just to have their own space (and let you have space too).

 

 

Not enough space for an annex for the grandparents, we are in a development on a 208 SQ. wah lot. I would have preferred a much larger non- development spot but my wife put up with 10 years of living without close neighbors in the USA and wanted to feel more secure, I opted to go with her wishes.

I designed the home with the parents on the first floor and partial privacy and large outdoor areas with gardens as we spend most of our time outdoors anyway. The second floor will be for my wife, myself and our sons.

[Aguda]

1 hour ago, maxpower said:

I just corrected and pointed out that switches are available if required. Doubt you will need such complications :)

 

Follow Crossy with the separate circuit idea and all should be good. Avoid the "one circuit does all"  Thais love so much.

Now you are talking oven water heaters and future AC there might come a point where your supply size gets a little stretched. Just a thought.

Definitely going with the separate circuits, makes excellent sense. Our family makes do without AC now and don't feel the need for it. I just felt it may be wise to prewire for AC in case  we ever want it.  If we need to upgrade the service and panel, should I run a heavier gauge main wire now?

[carlyai]

@Crossy Why a 10 ma RCD on the pool?

 

If the pool pump has no electrical connection to the pool, the lights are low voltage and transformer coupled, and the pump and equipment are isolated from the pool.

 

 

 

Sent from my SM-J700F using Tapatalk