Help make my home a safer place

[dev]

Hey experts out here...

I'm in need of some help/advise on how to make my house a safer place with respect to electrical stuff. My electrical knowledge is pretty much limited to the readings from Crossy sites, Forkinhades pinned thread and various threads around in the electrical forum.

Background:

First of all, the house comes with 4 x CU situated in:

1. Living Room;
2. Kitchen;
3. 2nd Floor;
4. 3rd Floor

While i dont quite understand why a 30sqw house requires 4 CU, i've enclosed a photo of how it typically looks like at the end.

Electrical sockets in the house come with 3-pin sockets. I've checked the wiring behind the socket and it seems to have some kind of grounding. But, i've yet to locate the ground rod though.

All the wiring in the house are concealed in the wall or under the false ceiling, which makes re-wiring the whole place very pricey (including hacking and touch-up).

My intentions...:

I'm thinking of replacing all 4 CUs with added safety devices.

• Living room CU: 1xMCB, 1xRCD, 1x20A RCBO10A for outdoor circuit (including my water pump), 1x20A CB (Power), 1x10A CB (light)

• 2nd Floor CU (1 x bedroom): 1xMCB, 1xRCD, 1x32A RCBO10A for water heater, 1x20A CB (aircon), 1x20A CB (power), 1x10A CB (light)

• 3rd Floor CU (2 x bedroom): 1xMCB, 1xRCD, 2x32A RCBO10A for water heaters, 2x20A CB (aircon), 1x20A CB (power), 1x10A CB (light)

• Kitchen: Really need help here. What needs to be dedicated and what can be shared.

Q: This is what I've come up with so far. Not sure if this configuration is viable and safe. Any comments/advises are most welcomed. I'm probably going to grab Schneider electric for all my breakers and CU (any other suggestion?).

Q: Also, do I need any kind of surge protection device? If so, can i put it at the main wire before it splits to 4 CUs?

What i don't quite understand yet...:

From what i've read, the main breaker or circuit breaker seems to be rated in 16A, 20A, 32A etc etc. However, the current CU rating seems to be 10kA for main and 5kA for individual. Or did i miss something out somewhere?

In translation to my above configuration, what kind of rating should i get for my MCB?

Your advise is greatly appreciated. Thank you!!

Oh, and special thanks to Crossy and his sites, as well as Forkinhades pinned thread.

Regards,

Ethan

Edited May 13, 2015 by dev

[T_Dog]

You will have to thoroughly check out your wiring to make sure you have no shared neutrals if you are going to use RCBO/RCD breakers, as they look for equal currents in each branch. The way houses in Thailand are wired, I would not expect dedicated hot/neutral lines on each circuit. A whole house protection unit might be easier to implement.

[dev]

Thanks for the quick reply T_dog.

I would very much like to check through all the circuits physically to be damn sure. However, all of the wiring are concealed within the wall or inside those false ceilings. Henceforth, it makes the thorough check pretty taxing. A whole house protection unit? Could you define further?

Thanks!

[bankruatsteve]

First off, some terminology: Those are circuit breakers (here they call them MCB's). A "CU" is usually referred to as the box that holds the circuit breakers. I can't see the main breaker amp but that should be rated relative to the meter. Your idea for circuits is OK but the other concept is to have circuits that isolate common things. Like A/C each with own circuit or all on one. Same with water heaters. I like to put 2 circuits in the kitchen - just because that's where some high watt devices are usually running at the same time - so it's nice to divide them up between 2 circuits. Lights can be on one circuit or separated for perhaps an emergency device. Room sockets can be on one circuit or more depending on number/rooms/etc.

Your "safety" device can be a main RCBO - you don't really need to have a separate RCBO for each circuit. IE: you would want to put in a new CU with 6-12 slots for MCB and have fun deciding how to run the circuits - that's assuming you can arrange from existing wire runs.

Otherwise... your only viable option for what you want is to simply replace the main breaker with a RCBO.

[Forkinhades]

Just a quick note

The 2 different ratings on your MCBs are

16A is current rating for the circuit

5KA is how much current the MCB can handle in FAULT conditions, more than this then the current simply 'jumps' over MCB causing fires and explosion.

Many many different ways you can configure, and you will get lots of suggestions here.

To get things rolling

New 8 way DB

New Front End Safety Cut

New Whole House Surge Arrester

Will need more info for your kitchen, and size of water heaters etc etc, length of cable run

[dev]

First off, some terminology: Those are circuit breakers (here they call them MCB's). A "CU" is usually referred to as the box that holds the circuit breakers. I can't see the main breaker amp but that should be rated relative to the meter. Your idea for circuits is OK but the other concept is to have circuits that isolate common things. Like A/C each with own circuit or all on one. Same with water heaters. I like to put 2 circuits in the kitchen - just because that's where some high watt devices are usually running at the same time - so it's nice to divide them up between 2 circuits. Lights can be on one circuit or separated for perhaps an emergency device. Room sockets can be on one circuit or more depending on number/rooms/etc.

Your "safety" device can be a main RCBO - you don't really need to have a separate RCBO for each circuit. IE: you would want to put in a new CU with 6-12 slots for MCB and have fun deciding how to run the circuits - that's assuming you can arrange from existing wire runs.

Otherwise... your only viable option for what you want is to simply replace the main breaker with a RCBO.

Noted your mention on the terminology.

You are right. My intent is to:

1. Have a main RCD+MCB (or RCBO depending) <-- rating?
2. Put my A/Cs for each floor on individual 20A MCB.
3. Put my water heater on a dedicated 32A RCBO10mA (or 30mA depending)

Thanks and regards.

[dev]

Just a quick note

The 2 different ratings on your MCBs are

16A is current rating for the circuit

5KA is how much current the MCB can handle in FAULT conditions, more than this then the current simply 'jumps' over MCB causing fires and explosion.

Many many different ways you can configure, and you will get lots of suggestions here.

To get things rolling

New 8 way DB

New Front End Safety Cut

New Whole House Surge Arrester

Will need more info for your kitchen, and size of water heaters etc etc, length of cable run

Thanks for your reply and noted on the rating of the existing circuit. May i ask how to identify that it's 16A? Unlike those MCB we are seeing these days where the rating is clearly written, the one in the photo just had like "5kA - 240/415V".

Some clarification (sorry my electrical knowledge is as good as none):

• New 8-way DB = A consumer units that can hold up to 8 x single-pole MCB?
• Front-end safe t-cut akin to "main RCD+MCB" or "main RCBO" right?
• Whole house surge arrester: can this be done at the main incoming (downstream of the meter) or do it on each CU?

My kitchen will be packed with the basic electrical appliances: 2Dr Fridge, washing machine, RO water filter, oven, microwave, kettle and a coffee machine. I'm thinking of catering 2 x 20A MCB power circuits for all these appliances and 1 x 10A MCB for lightings.

PS: Won't be doing the electrical works myself, as I think i might be a hazard to myself. But i'll be buying all the materials....

Thanks again.. and best regards..

[dotpoom]

Why not leave the electrical stuff to an electrician?

[Forkinhades]

Give us a rundown of your exact requirements, how many lights sockets in each room, the ratings (watts) of your water heaters.

We will tell you the size of cable and MCB to use.

The circuit rating on the MCB will be in Amps (ie no 'K')

[Tapster]

Both a comment and an on-topic request from me:

• I've just had some work done by a German electrician who certainly seemed to know his stuff. He fitted one RCD for the whole house and, very kindly didn't charge me for it saying that we should see what happened after the first rain, as there were often weird earth leaks in Thai wiring and the RCD might trip constantly and be useless. He didn't seem concerned about the safety of the house if the latter happened.
  
  Sure enough, now it has rained and I've had to remove the RCD from the circuit as it won't reset at all.
  
• My question: is this a safe situation to be in?
  
• What does it mean if I get a very light electric shock from the PC end USB cable, plugged into a printer on this circuit? I'm pretty sure I shouldn't!
  

Cheers!

[Forkinhades]

I wouldn't say that there was anything weird with thai electrics, just that you have accessories that are getting ingressed with water after a downpour. You need to find these accessories and fix them.

If you are getting tingles on equipment, then your earthing arrangements are not correct.

Please read the pinned threads.

[Tapster]

Fair enough.

Thanks for the advice.

I'll read up on it and post again if I can't sort it out myself.

)

[Tapster]

That's supposed to be a happy smiley.

Bloody mobile app!

[Forkinhades]