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# Lighting Circuits Connections for Interior Electrical Installations

Home / Technical Articles / Lighting Circuits Connections for Interior Electrical Installations

## Introduction To Lighting Circuits

Electrical lines which include lighting circuits begin from the main distribution panel of the installation and each line contains three conductors: phase, neutral and ground. All three conductors reach to the terminal point of each luminaire and if it has a metal chassis the ground should be connected in the appropriate position.

From each main distribution panel at least two lighting supply lines are leaving, so a failure on one line does not sink the entire installation in the dark. Insulation on the conductors must show the colors required by the regulations.

The phase conductor must be brown or black, neutral conductor must be light blue and ground conductor must be yellow/green.

To understand the circuit connections we can use various designs, including the following:

### Single line diagram

Circuits shown are in the simplified form. These drawings show only the important elements of the lighting circuit and contain information on how to layout, number of the conductors and their cross – section.

### Analytical diagram

Which show all the lines that connect the different parts of a circuit. These plans in large scale circuits can lose their figuration.

### Operating diagram

Which show in detail the paths of electrical current. This method of design is descriptive and easy to read.

## Lighting Circuits Connections

Single line diagrams, Analytical and Operating diagrams

### 1. Simply light circuit

Description:

Connection of one or more luminaire points (Lights) controlled by a simple switch. This kind of connection is used in almost all interior electrical installations.

#### General diagrams

Single line diagram

Analytical diagram

#### Operating diagram

Important Note:

In all lighting circuits a ground cable must be installed. Usually the luminaires for residential use belong in the next two categories:

• Protection Class I: The device is grounded. The ground wire (yellow / green) must be connected to the clip marked with ground symbol.
• Protection class II: The device is double insulated and cannot be connected to the ground.

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### 2. Selector switch lighting circuit (Comitater)

Description:

A connection of two groups of lamps controlled by a single point. The connection is usually used in chandeliers.

#### General diagrams

Single line diagram

Analytical diagram

Important Note:

During the design of various electrical circuits we pay attention to draw them in break mode (OFF), unless there are compelling reasons to the contrary. Above the circuit is ‘closed’, feeding all the lights.

#### Operating diagram

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### 3. Two-way switching lighting circuit (Two extreme switches Aller–Retour)

Description:

Control of a lighting circuit from two points (A and B). This type of circuit is used in hallwaysrooms with two entrances, stairs, bedrooms, e.t.c.

#### General diagrams

Single line diagram

#### Analytical diagram

With rotary switches

With pushbutton switches

#### Operating diagram

With rotary switches

With pushbutton switches

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### 4. Switching lighting circuit (Aller–Retour) with two extreme switches and one or more intermediate switches

Description:

Control of a lighting circuit from three or more points. This type of circuit is used in large roomslong corridors, staircases and generally in large rooms.

#### General diagrams

Single line diagram

Analytical diagram

#### Operating diagram

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### 5. Lighting circuits with fluorescent tubes

Description:

1. Circuit of a 40W fluorescent tube, with 40W Ballast and starter.
2. Circuit with two fluorescent tubes (20W each), with 40W Ballast and two starters (20W each)

The fluorescent tubes are used particularly in factories, offices, for decoration and advertising or promotion of goods. In recent years fluorescent tubes are used in residential installations.

#### General diagrams

Single line diagram

Important Note:

In figure b) we can add more fluorescent tubes if we want in series but we should also add more starters and a more powerful ballast.

#### Operating diagrams

Important Notes:

In figure 2) If one of the two starters or one of the two lamps stop working, then none of the lamps will eventually function.

The metal chassis of the lamp or the ballast’s choke should be grounded. The fluorescent tubes import reactive power to the grid. With new European Union directives, mechanical ballasts are repealed and only electronic ballasts (triac) should be used, which limit the reactive power.

The starter and the capacitor are abolished and we have direct ignition of the lamp.

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Bachelor in Electrical Engineering from Technological Educational Institute of Piraeus, Hellas. Electrical engineer working at Center of Renewable Energy Sources. I work in the field of maintenance, functional test and installation of measuring systems, including wind potential measurements in areas where wind turbines will be installed. I'm highly interested in HVDC systems, Fuel Cells technology and Microgrids.

1. Gideon anongor
Oct 26, 2021

Where a Can I get to learn the single line diagram

Feb 28, 2017

thanks a lot for every one on this site.
thanks for ever for all.

3. Tim Keane
Feb 23, 2016

You explained about Lighting Connections well with diagrams so that everyone can catch it easily. And it was a great article. Thanks for sharing it.

4. Alok Singh
Jul 17, 2015

Very great effort Edvard, very useful articles in a single click, thanks a lot for sharing with us…

• Edvard
Jul 17, 2015

Thank you Alok! For this particulary technical article a big thank goes to Emmanouil :D

Jun 30, 2015

It is very usuful side

6. calibre
May 07, 2014

Hello,

Very usefull website! Can you tell me in what software program the diagrams are made?

Thanks!

May 07, 2014

Microsoft Visio

Dec 19, 2013

Thanks for you valuable efforts.

8. hardyparvaiz
Feb 05, 2013

Useful Site.

9. vnnhan
Dec 26, 2012

I am very happy to join EEP, I have learned a lot. Thanks very much..

10. engr.sahir
Dec 12, 2012

I am happy to join the EEP and have to learn alot.

• Edvard
Dec 12, 2012

Welcome Sahir! Glad to have in the EEP team!

11. Edvard
Dec 07, 2012

Excellent overview of lighting connections. Just keep on!!

Best regards

Dec 07, 2012

Thanks a lot Edvard…

12. Bipul Raman
Dec 07, 2012