Electrical Wiring

[Morakot]

Could someone explain if this is common. I have come across wiring where the wires of two wall cable are connected together to feed into an outlet. Why?

The pictures show the open outlet with the wires and the counterpart (note the colour coding).

[Crossy]

You will likely find that one cable comes from the distribution board and the other feeds to another outlet. Daisy-chaining outlets is perfectly acceptable and is a quite normal way of wiring outlets in many (if not most) Western countries.

Twisting the cables together with a short pigtail (because 2 wires won't fit in the terminals) is not so acceptable (there should be one wire in each end of that group you show in the second photo.

[Morakot]

You will likely find that one cable comes from the distribution board and the other feeds to another outlet. Daisy-chaining outlets is perfectly acceptable and is a quite normal way of wiring outlets in many (if not most) Western countries.

Twisting the cables together with a short pigtail (because 2 wires won't fit in the terminals) is not so acceptable (there should be one wire in each end of that group you show in the second photo.

Thanks! This makes sense.

[electau]

The method is known as looping and is the normal method of wiring, loop between light switches or looping between socket outlets or light fittings.

Usually the max number of wires that can be accomodated in a socket outlet terminal is 4 based on 2.5sqmm. However connecting the wires in an approved connector with a single wire to the terminal is permissable provides that the connection is within the wall box or is directly behind the socket outlet ie less than 100mm. the same applies to switches and light fittings, ie within the fitting. In other cases a juction box may have to be used.

When wiring there must be no interconnection of circuits.

Edited August 12, 2012 by electau

[Morakot]

I have another question.

I turn off a circuit breaker and connect Neutral to Earth on a random cable in that circuit (Live on that cable is seemingly off). Connecting N to E results in the in main RCBO been triggered. What is happening with the wiring?

[Crossy]

Normal operation is happening

You want a full technical description of why a N-E fault on a dead circuit trips (sometimes) an RCD?

[electau]

I have another question.

I turn off a circuit breaker and connect Neutral to Earth on a random cable in that circuit (Live on that cable is seemingly off). Connecting N to E results in the in main RCBO been triggered. What is happening with the wiring?

The line of the circuit L and the neutral N of the circuit are connected to the RCBO terminals.

There must not be any earth on the neutral or line conductors of the circuit connected.

There must be no interconnection of circuits.

An earth fault on the L conductor will trip the RCBO. An earth on the neutral conductor may trip the RCBO due to small value of out of balance current between the neutral and the earth conductor in some cases when there is no supply at the RCBO and the RCBO is switched ON.

A permanent earth fault on the neutral may inhibit the operation of the test button.

　

Edited August 13, 2012 by electau

[Morakot]

Thank you, chaps! I think, I am satisfied if that's a "normal" operation.

[thaibeachlovers]

I'm confused by your photo. What would be the earth wire back home ( green and yellow ) appears to be L or N and the L ( black ) appears to be not in use.

However, TIT. Nothing electrical here surprises me now.

I notice that they haven't even been able to have all three plugs/ switches the same way up, LOL.

[Morakot]

I'd like to install a joint box, to fix the unconventional wiring above the ceiling in my office. I've bought this box and a terminal block.

What is the best way (easy and safe) to install this onto a wall? I was thinking of putting the box on the wall with screws and just have the block suspended by the connecting the wires inside the box.

[electau]

I'd like to install a joint box, to fix the unconventional wiring above the ceiling in my office. I've bought this box and a terminal block.

What is the best way (easy and safe) to install this onto a wall? I was thinking of putting the box on the wall with screws and just have the block suspended by the connecting the wires inside the box.

Affix the box onto the wall. For each individual circuit connect all L conductors to one terminal, all N conductors to a second terminal and all E conductors to a third terminal.

If you only have one circuit you will use 3 terminals only. otherwise 3 terminals per circuit.

The terminals must be enclosed within the box, so you will have to replace the lid (no exposed live terminals or connections).

[thaibeachlovers]

I have another question.

TheI turn off a circuit breaker and connect Neutral to Earth on a random cable in that circuit (Live on that cable is seemingly off). Connecting N to E results in the in main RCBO been triggered. What is happening with the wiring?

The line of the circuit L and the neutral N of the circuit are connected to the RCBO terminals.

There must not be any earth on the neutral or line conductors of the circuit connected.

There must be no interconnection of circuits.

An earth fault on the L conductor will trip the RCBO. An earth on the neutral conductor may trip the RCBO due to small value of out of balance current between the neutral and the earth conductor in some cases when there is no supply at the RCBO and the RCBO is switched ON.

A permanent earth fault on the neutral may inhibit the operation of the test button.

　

<There must be no interconnection of circuits>

LOL! The house I live in has 2 circuit breakers. One for the front of the house and one for the back. It's an improvement on the last house where there was one circuit breaker and the feed went through a 1.25 wire.

While attemping to replace a burned out light switch in a relative's house, I was flummoxed by the fact that all three lights operated from the one box were live on the light side of the switch.

TiT indeed.

[Morakot]

Here another "before-and-after" for general appreciation and comments.

I have redone the existing wiring in one room, while I had the ceiling open for some interior design work. I hope this will have slightly raised safety standards.