House Wiring Philosophy

[T_Dog]

Working on the wiring plans for the house, and one common approach is to segregate the lighting 1.5 square mm wiring from the outlet's 2.5 square mm wiring. Another approach is to combine lighting and outlets using 2.5 square mm wire and use zone breakers for outlets/lights. Wondering what others are doing here in Thailand. The advantage of combining lighting and outlets is that you can standardize on 2.5 square mm wire for all those circuits and not have any 1.5 in the house. (Still need heavier wire for water heaters and ovens.) With our house design, bringing combined outlet/lighting into zones would greatly simplify things.

Another question I have is the daisy chaining of breakers. What are the pitfalls of having a pole consumer unit in a weather-proof box with (let's say) a 60 amp breaker and then going to underground cable to the house where there is another two-pole 60 amp breaker in series. (Assuming here the wires are of sufficient current capacity.) Are there codes in the USA or the UK that advise against putting two-pole breakers in series?

Interested to hear the wiring philosophy or codes others are following.

[Crossy]

As a Brit I cannot comment on US practices or regulations.

UK regulations do NOT prohibit the combination of lighting and power although we do not normally do it. In the UK such an arrangement would be considered primitive and would normally be found in older buildings with few power points. There could also be issues with the required current rating of the light switches being protected by a 20A breaker.

If you do decide to combine it is important to realise that ALL cables must be capable of handling the currents allowed by the breaker, no bunging in a bit of 1.5 for that new light over there.

The major disadvantage is that if the breaker operates you lose all power to that zone, so every source of light goes out (the TV is a great source of light when the lighting circuit pops).

Personally, unless it was a very small installation (shack), I would not do it. I prefer to break up the installation over a larger number of breakers rather than a smaller one, a single breaker opening should have a minimal impact on the safety (darkness) of the occupied area.

Just ensure that your installation is well documented so that future maintainers can have at least an idea of what's going on.

As to daisy-chaining breakers, no safety issue whatever, biggest problem would be discrimination, i.e. determining which breaker was to open first. It is absolutely guaranteed that the breaker on the pole will open only when it's dark and pissing down, any other time the one in the house will operate first.

[T_Dog]

As a Brit I cannot comment on US practices or regulations.

UK regulations do NOT prohibit the combination of lighting and power although we do not normally do it. In the UK such an arrangement would be considered primitive and would normally be found in older buildings with few power points. There could also be issues with the required current rating of the light switches being protected by a 20A breaker.

If you do decide to combine it is important to realise that ALL cables must be capable of handling the currents allowed by the breaker, no bunging in a bit of 1.5 for that new light over there.

The major disadvantage is that if the breaker operates you lose all power to that zone, so every source of light goes out (the TV is a great source of light when the lighting circuit pops).

Personally, unless it was a very small installation (shack), I would not do it. I prefer to break up the installation over a larger number of breakers rather than a smaller one, a single breaker opening should have a minimal impact on the safety (darkness) of the occupied area.

Just ensure that your installation is well documented so that future maintainers can have at least an idea of what's going on.

As to daisy-chaining breakers, no safety issue whatever, biggest problem would be discrimination, i.e. determining which breaker was to open first. It is absolutely guaranteed that the breaker on the pole will open only when it's dark and pissing down, any other time the one in the house will operate first.

Crossey... As always, appreciate your perspective on things. The issue with lights going out when an outlet overloads is an obvious one, but what is even worse is an entire floor losing lights. Your observation about switch current rating is something I had overlooked, and I appreciate that insight.

Thank You again for our comments. A Square-D 16-holer should allow me to to do it right if the wire routing looks like it makes sense. Based on your comments, I think I might do lighting in east and west zones over two floors. That would allow segregation of the lighting and outlet circuits and keep some of the lights on in a given area when a breaker trips.

[Crossy]

What could be worth considering if your house really lends itself to zoning (such as a traditional Thai home which is effectively several independent buildings) would be to run a sub-main to a small consumer unit in each area which would then have separate lighting and power breakers.

I initially looked at this arrangement as the home we are building would lend itself to doing things this way. In the end I decided against it due to the requirement for UPS and genset backup for certain circuits making the wiring complex and expensive on materials.

The scary bit is, despite our home being only 3 beds, a lounge, kitchen / diner and my workshop, we end up with 28 MCBs, 2 RCDs and an RCBO in three consumer units.

[haveaniceday]

There could also be issues with the required current rating of the light switches being protected by a 20A breaker.

I overlooked this too, thanks.

Golden, our local "electrical supply shop" the biggest switch you would have on the wall in your house is rated at 16A.

I want each outlet to have a on off switch, this is the switch our "wise" sparky is planning to put in on a 2.5mm 20A circuit.

Although it is unlikely, I would use more than 16A though a particular switch, this would effectively make the switch the breaker right ?

Assuming these gadgets work at their actual rated amounts.

I can see a drive to the big smoke coming up this weekend !!!!

T_Dog, FYI, it seems common here to combine lighting and outlets.

Although not exactly the case, in my case, we have 3 single phase circuits.

Our 5th sparky now, insist on putting all bedroom lights & outlets to consumer box #1

All lights / outlets in "My Den" aka computer room / escape room, lounge, kitchen outside lighting, (some 20+ lights) onto consumer box #2

All Aircons, ( at least 4 ), hotwater system, water pump bundled together on to consumer box #3.

Absolultly no concept of sharing the load around. Watch them like a hawk.

I don't know much about this subject, but common sense and a gut feeling something is up seems to be better than the local sparkies in Thailand doing domestic stuff.

[electau]

If you have more than one floor and have outbuildings one can have the main switchboard at the main building and a distribution board at the upper floor of the house, and a distribution board at each outbuilding.

An earth conductor should be run to each distribution board from the main switchboard with the sub mains.

On each board a minimum of 2 light circuits, and 2 power (socket outlets) other circuits as required.

If the TT system of earthing is used RCD protection will be required on all final sub circuits.

Main earth and electrode from the main switchboard.

　

In general, a typical residence only requires 2 lighting and 2 power(socket outlets) with other indivual circuits as required , eg, HW, Aircons etc.

(Based on Australian wiring and installation practice, and AS3000). With exception to the reference to the TT system).

It is mainly a question of cost which way one goes, 1 main switch board and sub circuits or 1 main switchboard with distribution boards and sub mains.

[Crossy]

I want each outlet to have a on off switch, this is the switch our "wise" sparky is planning to put in on a 2.5mm 20A circuit.

Although it is unlikely, I would use more than 16A though a particular switch, this would effectively make the switch the breaker right ?

Assuming these gadgets work at their actual rated amounts.

A 16A switch on one outlet should be adequate. The 16A rating is what it can reliably switch rather than what it can carry (many times greater) so it's unlikely to fail in normal use (don't use it to turn off the 3kW electric barbecue). If you do get a fault that opens the breaker the switch may weld closed, but they are cheap enough to replace.