Electircal rework some help needed please...

[benlovesnuk]

Hi,

 

Thank you for your visit.

 

Im reworking the houses electrics, as Ive found a few anomalies and oddities. I would just like to check over if anyone has the info on the following please..its just for clarification, everything will be turned off at the mains and checked before being worked on.

Consumer unit will hopefully be something like:

oven (1st mcb)

shower heater x4 (5mcb total) Will plan to upgrade to RCBO

Ac x 2 (7 mcb total)

downstairs sockets (8thmcb)

upstairs sockets (9thmcb)

downstairs lights (10thmcb)

upstairs lights (11thmcb)

Outside sockets (12th mcb) upgrade to rcbo

Outside lights (13th mcb) upgrade to rcbo (if needed)

Ceiling fans x 6 (want to separate from lights)14th mcb

 

1) I want to put automatic circuit breaker on oven which has its own mcb currently its a 4mm cable, (should I go to 6mm) and I believe if I stick with 4mm its a 25amp?

 

2) Same for the aircon its a 15,000 btu inverter type and 9000 btu inverter, recommended cable and amps on mcb please, its currently 4mm on 32 for the 15,000 btu (9000 not yet installed ), which seems either too small of a cable or too high amperage? Also an automatic circuit breaker on the aircon to match.

 

3) shower heaters currently installed are multi points 6kw(currently 4mm on 32amp) and 8kw (currently 6mm on 40 amp), is this correct or needs changing(will when finished have 4 heaters)

 

4) We run a single phase 15(45) meter with mains underground in protective conduit, its a 16mm cable which is the one PEA recommends however it goes about 50 meters to the consumer is it possible to upscale this to 25mm, is it worth it? I have another outbuilding that is 70 meters from meter (yet to be added) I would like to know if I should get 16mm or 25mm for this?

 

5) I think , lastly, is it ok to have 15-20 double mains sockets on one mcb as the house is quite large, it has about this downstairs and the same again upstairs, I have an 18 fuse board but Ive got a lot to get on?

 

First I will rework the network of spaghetti and correcting fuses and cables, then afterwards add rcbo and Rcd protection, the idea is to have water heaters and outside sockets on rcbo and everything else on the rcd does this sound right, and does anyone have a handy layout they think is useful? I have only ever seen split rcd or full rcbo.

 

Thank you for anyone who can help...

regards

 

[Crossy]

OK, a few answers.

 

1) For your oven, 4mm² cable should be fine unless it's an industrial strength oven (check the oven rating), cable is good for around 30A.

 

2) 4mm² cable is more than adequate for your aircons (most domestic units are fine on 2.5mm²), use 32A breakers to protect the cable and avoid trips on startup.

 

3) Heater cables and breakers are fine.

 

4) Unless you are seeing volt-drop problems your 16mm² feed is fine, less than 5% drop at 50A. For the outbuilding feed. What do you intend having in there lights and a couple of outlets or a hobby machine shop? For most usage a 6 or 10mm² sub-main would be more than adequate, if it's underground an RCD at the source end would be a good idea.

 

5) There is no limit to how many outlets you can have on a circuit, the cable is protected by the MCB and most modern appliances are very low power. Run two circuits to the kitchen where the high power stuff lives.

 

Your RCD/RCBO combo looks ok, run a dedicated circuit on an RCBO (or even an MCB on the unprotected side of the CU) for your freezer. Just put the RCBO's next to the main breaker (no RCD), then the RCD and the MCBs.

 

You'll need a DIN mount CU, the plug-in ones are difficult to configure as splits.

 

[benlovesnuk]

Hi crossy

 

Thank you for your detailed and thoughtful answers. If I could take your time a little longer it would be greatly appreciated...

 

At the moment I have a Schneider 18 fuse plug in so if I go split in this way I need a Din plug CU, any recommendations? 

 

With regards to the 2nd building, I wanted to add a new mains as the electrical supply and charging is for rental purposes, its a 1 bed 1 bathroom 1 kitchen rice barn about 100m2. it is currently 75 meters away from the meter but only 35 from the house.

 

Im interested about your idea about sub CU is there a way to add a units counter or meter to see how many KWh are used, or is it best to stick with adding a new meter?

 

Lastly the automatic breaker is a haco ws232l as this is the series I run around the house the haco tandj. Is this alright for aircon and ovenjust before the unit where both the ovens and a/cs run directly back to the mcb?

 

Regards

 

Ben

 

 

 

 

[Crossy]

OK Ben.

 

We have 16 way ABB System ProM consumer units, they weren't cheap for what is effectively a plastic box with a DIN rail. You should be able to get similar for rather less $$$, but do make sure you get one with a metal DIN rail. The existing unit can be relegated to the rental.

 

If you are running individual circuits for the aircon, oven, water heaters there's no need for local isolation (the Haco breaker) unless you want it. None of ours have it.

 

For your rental, let's say 2 x 12,000 BTU aircons, 3.5kW water heater and "normal kitchen appliances" (fridge, microwave, kettle, gas cooktop). A quick and dirty prospective load guesstimate gives us about 25A (assuming the air is mostly run one at a time). In reality when the occupants are home it would run at 4-10A with blips to 20A when the shower is on. You could run that off a sub-main from your main CU, DIN mount energy meters are available for a neat installation (AliExpress is your friend).

 

BUT

 

Dependent upon your aircon requirements (are you an Arctic Fox?) you are possibly already pushing your 15/45 with the existing load so a separate meter and feed from the road my be advisable. You will need to talk to your local PEA office, some will only supply one meter per chanote and a new supply will need the new installation inspected. I would install a meter in the rental anyway so you can charge only for what has been used during the rental period (assuming a holiday let type arrangement).

 

What would I do? I'd run a sub-main from the house in the first instance (less cable, less hassle with PEA) and see how the existing supply handled the load. With a 63A incoming breaker all would likely be just fine. If you do experience issues (volt drop, incoming breaker opening) you can move to Plan-B.

 

 

[benlovesnuk]

Hi Crossy

 

Thank you for your advice again and your detailed response is greatly appreciated.

 

Firstly, in regards to the rcbo and din rail, the rcbo from Schneider that I saw was about 1100 badt and was the same push type connector as I have now. This goes for the double pole rcbo with tester.

Now, firstly If you dont mind bearing with me a few more questions, what is the difference between the rcbo double pole and rcd? As many places only have the rcbo double pole in a 50 amp or 60(about 2200 badt), I cant seem to find RCD breaker only, at least in the Schneider brand (or stupidly is it the same thing?).

 

Our first "electrician" did put in a 63 amp breaker but when the PEA came round to check install, earth etc, they insisted we put in a 50 amp, so it was changed. I can put it back but we havent really had any issues with power, the only thing you notice is when the water heaters kick in you get a dimming of lights momentarily.

 

I do like your sub mains idea, is there any info and drawings on this that you know of?

 

Thank you for your time and patience with my questions, all the best.

 

Ben

[benlovesnuk]

sorry to add..... the guesthouse is a teak wood rice barn, it at most will have 1 aircon probably 12,000, 1 water heater maybe 6k as we are in chiangmai (winter well water is cold), and as you say tv fridge etc

 

What size cable and peripherals would it likely be?

 

Regards

 

Ben

[bankruatsteve]

The double pole RCBO is usually used as a main breaker.  The single pole RCBO is used on single circuit.  There is no stand alone RCD for Schneider that I know of.

[Crossy]

Steve has it.

 

The plug-in CUs don't allow you to do what you suggested earlier. You can either have a big RCBO as the main switch (2,500 Baht) and the rest as simple MCBs, cheapest way to go, but of course, RCBO trips, everything goes off.

 

OR

 

You can use the 1,500 Baht single-width RCBOs on each circuit (retaining the existing front-end MCB), this is rather more expensive, but it does mean you can have un-protected circuits for your freezer and the like. Trying to get this working on an existing home which was wired by a Thai will be fun. Shared neutrals are the enemy of individual RCBOs

 

For your sub-main, I would split the supply before it enters your CU, possibly use a small CU which would allow you to still have a single point of isolation, populate it with 2-pole MCBs, one going to your existing CU, the other to the external cable.

 

[benlovesnuk]

Thank you both.

 

Ah ......now I understand about the neutral, this is, amongst other things what I have be redoing in the house. So in regards to circuits, chasing them back taking them out and refitting where the neutral is only for that fuse circuit, because I had found that they hadnt bothered to run it all the way and shared from a different fused radial. But for all of my water heaters (and i presume these are the only ones that need rcbo protection) these are all from cu straight to heater. Where as lights and mains do seem to have some sharing of neutral to the CU but I am slowly working on all of these to be only run from one neutral back to CU. However the whole upstairs needs to be ripped out,

 

Currently Ive reworked it from all 18 fuses with some unknown fuses doing nothing, to 14 mcb's That I can whittle down further

(4x32amp) water heater, water heater 2, water 3, AC1 (12,000btu) all 4mm 4mm earth (probably be getting 8k heater and 6mm cable for this.

(4x25amp) oven only, mains downstairs, mains kitchen, outside mains with pump 4mm 2.5mm earth

(3x20amp) mains upstairs, all ceiling fans, mains downstairs back lounge 2.5mm 2.5mm earth

(3x16amp) lights outside, lights downstairs, lights upstairs 1.5mm same earth

 

Anyway this now helps me make a more informed decision.

 

Could you run main double pole, than let say mcb for freezer than the single pole rcbo for water heaters(4 in total) and then the double pole rcbo for other sources? Would this work.

 

Again thank you both for your answers, Crossy

[benlovesnuk]

Just to add as a side note, the single pole rcbo is 1150badt in global for the 6ka 30mill single pole, the 10mil is obviously more, and the same for the double pole rcbo 2250 which I have to say global out of all the companies including homepro thaiwatsudu, homedor, do home, home expert et al in chiangmai generally do well. It doesnt have everything but everything it does have I will always tend to purchase from them. tools are ok, ive actually got most from home pro as they tend to have good clearance items. in regards to electrical bits, conduit cables global are pretty good there are electrical only outlets but no cheaper and sometimes hard to get help because of all the trades in there. thanks

[Crossy]

7 hours ago, benlovesnuk said:

(4x32amp) water heater, water heater 2, water 3, AC1 (12,000btu) all 4mm 4mm earth (probably be getting 8k heater and 6mm cable for this.

(4x25amp) oven only, mains downstairs, mains kitchen, outside mains with pump 4mm 2.5mm earth

(3x20amp) mains upstairs, all ceiling fans, mains downstairs back lounge 2.5mm 2.5mm earth

(3x16amp) lights outside, lights downstairs, lights upstairs 1.5mm same earth

Don't run outlets on anything over a 20A MCB, may as well use 2.5mm for these, run two circuits for the kitchen. Outside outlets and lights needs to be on an RCBO (separate circuit best in case of the wet getting in).

 

Run the fans off the lighting circuit unless you're using these https://www.bigassfans.com/

 

7 hours ago, benlovesnuk said:

Could you run main double pole, than let say mcb for freezer than the single pole rcbo for water heaters(4 in total) and then the double pole rcbo for other sources? Would this work.

Yes, retain the existing MCB incomer, RCBOs for circuits that need earth leakage (water heaters, outside outlets and lighting), MCBs for the rest.

 

 

[benlovesnuk]

On 2/20/2018 at 5:09 AM, Crossy said:

Don't run outlets on anything over a 20A MCB, may as well use 2.5mm for these, run two circuits for the kitchen. Outside outlets and lights needs to be on an RCBO (separate circuit best in case of the wet getting in).

 

Run the fans off the lighting circuit unless you're using these https://www.bigassfans.com/

 

Yes, retain the existing MCB incomer, RCBOs for circuits that need earth leakage (water heaters, outside outlets and lighting), MCBs for the rest.

 

 

Hi Crossy

 

Thank you for your help, I ran the ceiling fans separately as I have 5 downstairs and 3 upstairs and just want to isolate them from lights I will sue 2.5mm and put them on a 20amp mcb.

 

I will show a picture of CU when finished as I would like to just make sure I understand correctly about the layout of rcbo and mcbs as weve discussed, before I start buying them, I dont currently have any other RCD or saftey cut installed so I want to make sure I get close to PEA guidelines and most importantly being as safe as possible once all the wiring is redone.

 

I do have one more question, about another ceiling fan and Haco speed switch, its the Haco W2716 400va 250 watt control. Is it possible to run 2 average size fans off this, or not? Much appreciated for your time.

 

Regards

 

Ben