Additional rooms, additional power.

[NanLaew]

We are currently adding a 3-bedroom annex on the back of the property that will need power.

 

The layout below shows in green and solid lines what is already in place and red and dashed lines what is proposed.

 

My first question is will we need to upgrade our current single-phase 15(45)A electrical service that serves the green bits to 30(100) A to support the new red bits?

 

What size wire from the main wall mounted breaker box, via conduit along the wall and up pole #2 (about 20 m) and wire-in-air to pole #3 to the annex (about 25 m)?

 

I will be using Schneider CU and fittings for the annex, same as I used for the office/workshop (man cave).

 

What size should the main breaker/RCBO be for the annex?

 

I plan on each room having its own 10A (lights), 16A (outlets) and 20A (aircon) service.

 

What size/type breaker for the 3200 W hot water shower units?

 

PS: (Non-electrical) we have already upgraded the water pump system, so that should manage to feed the 3 new bathrooms.

 

Thanks in advance.

 

[OneMoreFarang]

1 hour ago, NanLaew said:

What size should the main breaker/RCBO be for the annex?

 

I plan on each room having its own 10A (lights), 16A (outlets) and 20A (aircon) service.

 

What size/type breaker for the 3200 W hot water shower units?

 

You should select breakers according to the cable size. The idea is that the breaker disconnects before the cable gets too hot.

For a 3200W shower you need 3200W/230V = 13.9A. For that a 2.5sqmm cable is fine. And for that cable, and the load, a 16A breaker is fine.

Most modern AC need less than 10A. Look in the manual what they recommend (or the W and divide it by 230V).

 

There are lots of good videos on YouTube which explain about MCBs, RCCBs, RCBOs, and Amps and cable sizes. 

[NanLaew]

Bump.

 

The annex now has four rooms, each with its own ensuite and is going to have its own power line/meter and the Thai style house will be moved onto that line, just finalising things with the light company. The main house will be standalone.

 

So, back to internal wiring for the annex. With 4 air-conditioned rooms, each with en-suite bathrooms. Initially I was thinking a 14-breaker CU with four 16 A breakers for air conditioners, four 16 A RCBO/breakers for hot-water shower units, four 10 A breaker for room lighting and four 16 A breaker for the room wall sockets. That makes each room 'standalone' for power. I used Schneider Square D CU and breakers for my shed, so will go the same way with the annex.

 

I was also looking at the Schneider Square D CU that has 8+4 and believe with an RCD protecting the 4 slots on the right, this may be an option for having better protection for the shower units? But with only 8 breakers on the left side, that reduces my capacity for individual (4-each) aircon, lights and wall outlet power.

 

What's the safest, no-overkill (unfortunate pun) method for these hot water shower units? On a bus bar of four hanging off the RCD in the 8+4 CU? Or in the original 16-slot CU with individual RCBO's?

[Crossy]

Are the annex rooms going to be rented / Airbnb etc?

 

If so, you may want to consider an individual CU/distribution board for each room, you could then meter each room to see just how much juice each guest is using.

 

 

 

 

[impulse]

2 hours ago, Crossy said:

Are the annex rooms going to be rented / Airbnb etc?

 

If so, you may want to consider an individual CU/distribution board for each room, you could then meter each room to see just how much juice each guest is using.

 

Gotta admit, I haven't done this.  But if I were building a new system, I'd go with one of these power monitor systems to see what each leg of the system is using.

 

https://www.amazon.com/Emporia-Monitor-Circuit-Electricity-Metering/dp/B08CJGPHL9

 

I'd also agree with having a way to monitor usage in each room if the OP will be renting them out on a short or long term.  Or even if it's just to yell at the kids for using too much juice.  Tell them about when we were kids and only had one outlet in each room...

 

 

 

 

[NanLaew]

3 hours ago, Crossy said:

Are the annex rooms going to be rented / Airbnb etc?

 

If so, you may want to consider an individual CU/distribution board for each room, you could then meter each room to see just how much juice each guest is using.

 

 

No, it's for members of the extended family. Mrs NL has suggested that once they fly the coop, then they could be rented out, but I don't see that happening in my lifetime.

 

Any ideas on RCB and/or RCBO for the 'wet' appliances?

 

I am also going to run the wiring in half-inch white pvc conduit with surface-mounted switch and socket boxes, same as I did with my shed. Semi-industrial looking, but I have a feeling that the 'electrician' I will be watching over has loads of VAF building wire (no VAF-G!) and hundreds of those wall staples of yore.

Edited May 7 by NanLaew

[NanLaew]

OK, we are going with VAF and VAF-G building wiring for economies of speed and cost.

 

Looking at wiring gauge needed, does the following sound right?

 

1.5 mm = Lighting (all LED) on 10A breakers, VAF

2.5 mm = Wall outlets on 10 A breakers, VAF-G

4 mm = Air conditioners (< 10k BTU) on 16 A breakers, VAF-G

6 mm = Hot water shower units (4500 W) on 20 A RCBO/breakers, VAF-G

 

Looking at the Square D CU, and the desire for individual room circuits (4 rooms), will the following work? The 4 x lights and 4 x outlets would populate the 8 left slots and the 4 x aircon and 4 x tankless hot water heaters would populate the RCD-protected 8 right slots. Are there any issues running aircon on the RCD-protected lines?