A few questions about my electrical installation/ consumer unit

[Jurghh]

Hi All. I've been a lurker for a while, though never in this forum, but this is my first post. I hope to be able to contribute and help others in the future.

 

So here goes... I'm redoing the kitchen in my BKK condo and I want to add 4 new circuits (sockets & microwave, dishwasher, oven, water heater). The CU is located in the kitchen. I've already chased the walls and installed conduit & back boxes etc.

 

Initially I planned just to add standard MCBs like the ones currently installed but now as I've learnt a little bit more about electrics I think it's better if more or all circuits are RCD protected. Currently only circuit 6 (three down from the right, blue wire) is protected by an RCD. This is the circuit for the existing sockets in the kitchen. So i've got a few questions i'd be very grateful if anyone could help answer:

 

1. What would be the best way to add RCD protection given the layout of the 3 phase CU? To all circuits or is it less important for others? 

2. Could for example all of the existing MCBs be swapped out for 1P RCBOs? The Siemens ones have functional earth wires that need connecting. RCCBs an option?

3. Why did the installers use a 2P RCBO linked to an MCB to add RCD protection to the existing kitchen sockets instead of a single 1P RCBO?

4. Why did the installers break the colour pattern and use black wire instead of red for the bottom left L2 circuit?

All of the companies I've had round to do a survey and quotation haven't actually offered a solution in any detail.

 

 

[Crossy]

Looks like a nice installation to start with 🙂 

Is the ground bar actually linked to ground?

 

Those siemens MCBs seem to be normal DIN mount units rather than plug-in 🙂 

 

Single-width RCBOs that will fit are available, although not necessarily cheap. This is possibly why a separate RCD/RCBO was used for the kitchen. Do you have a part number for the Siemens units you found?

 

Sadly, it looks like you will have to extend the white neutral wires for the circuits you need to protect, but such is life.

 

Wire colours? "It's what was in the van guv"

 

I would decide which circuits you need to protect with RCBOs and then look at the costs. Certainly, I would do outside lighting and outlets, water heaters, kitchen outlets except for your fridge/freezer.

 

 

[Jurghh]

Thanks for the detailed reply. The ground bar goes into the wall with more heavy duty fixings than say the neutral bar. I loosened off the nut to see what kind of bolt's been used but the whole thing just kept spinning. That was the case for both nuts on the earth bar. There is continuity between the neutral and CPC wires at every receptacle that i've played around with and tested. There's also continuity between the ground bar and the neutral bar in the CU. 

 

You're right about the MCBs. They don't clip on to the rail like the RCBO below clips onto its rail. If the screw isn't tightened they won't hold on the rail. I've also noticed that the MCBs appear to fit a bit better the opposite way round (see new photo). There are no load or line markings on the MCBs so I think they can be used either way. 

 

Lazada link for the Siemens RCBO 5SU9. https://tinyurl.com/4ehvb246. These have line and load markings. I'm pretty sure they'll fit on the rail where the MCBs are. The bit that's confusing me is the blue neutral wire that they come with. Does that need to be attached at the CU? The MCBs only have a single cable (hot) going to each circuit.

 

Regarding the circuits to add RCD protection to, I've uploaded the CU wiring diagram. The fridge freezer is already on the circuit with the RCBO fitted.

 

 

[Jurghh]

After some more research I think i've found that all the MCBs can be changed to single width RCBOs. They fixed neutral wire attached to the RCBO is 60cm. That wire goes into the neutral bar and the neutrals from the load side (currently in the neutral bar) go into the top of the RCBOs. Those neutral wires will most likely need to be extended with inline Wagos.

 

Regarding the earth bar, i'm still confused by what's going on there. Could it be that the earth and neutral are connected somewhere before my consumer unit? 

[Crossy]

Earth and neutral are certainly linked somewhere in the installation.

 

In a condo it's likely that you have a TNC-S (or possibly TNS in an older place).

 

Have a look here https://en.wikipedia.org/wiki/Earthing_system

 

If you don't actually see a link then it's going to be elsewhere.

 

If you measure 220-230V between a live and the earth and something close to zero between neutral and earth you're likely good to go. In our old condo all the A/C units were supplied from live and earth!!! They worked just fine although I did move the connections to the right place 🙂