Primary Light Point; Secondary Light Point; House Wiring;

House wiring diagrams are given in this section which will be useful during electrification work in a building. Following points must remember while doing wiring –

• MS or PVC conduit is used for house wiring,
• The size of conduit depends on the number & size of wires,
• Two types of conduiting are done -1) Surface & 2) Concealed,
• Sub-Mains– Submain is a set of wires which is laid between the DB (Distribution Board) of the house & metering panel. The size of submains should be capable to carry current of total load which is connected with DB. Sub-mains are of two types –a) Three phase submains (3-phase wires R,Y,B + 1-neutral wire + 1- earth wire) & Single phase submains (1-phase wire + 1-neutral wire +1- earth wire). It depends on the type of three & single phase DB.
• Main Circuit– It is a set of 3 wires (1-phase, 1-neutral & 1-earth) which is laid inside the conduit between DB & first switch box. First switch box may be for lighting purpose or for switch& socket. Main circuit for light & light plug is fed from 10A MCB. Maximum 800W load can be connected with one main circuit or maximum 10 nos of points can be connected with one circuit. While main circuit for power point (16A switch & socket) is fed from 16A MCB.
• Half wire (First light point) – It’s a phase wire which is laid between switch & light point. This light point is called first light point.
• Loop point (Secondary light point)– Loop point is secondary point which is connected/looped with first point. Next loop point may be connected with first loop point & so on.
• point– It’s either a light or power point where light or equipment are connected. Light is connected with light point & equipment is connected with power points.
• Light plug – Light plug is a set of 6A switch & socket which is used for low current portable equipment like TV, RO, portable fan, mobile charger etc. Light plug is fed with 10A MCB or may be looped with light point.
• Power plug – Its set of 16A switch & socket which is used for high current portable equipments like domestic iron, geyser, refrigerator, AC, Heater etc. Power plug is fed from 16A/20A/25A depending upon the type of load.

Light wiring has been explained in the drawing given below  –

Wiring diagram for individual items –

In this section, wiring diagram of individual items has been given below for reference purpose –

Current carrying capacity of Copper wires–

Size of Cu wire (in sq mm)	Current (in Ampere)
1.o	11
1.5	14
2.5	19
4.0	26
6.0	31
10.0	42
16.0	57
25.0	71
35.0	91
50.0	120
70.0	160
(Note– Current carrying capacity may slightly vary according to different manufacturers.)

Guidelines for house wiring as per NBC – 2016 –

What is NBC & what is role of NBC here?

Let’s understand NBC first before moving ahead. The full form of NBC is National Building Code of India, it is a national instrument providing guidelines regulating the building construction activities which includes electrical work, air conditioning & ventilation, fire & life safety work etc across India. It is applicable for all agencies/departments involved in construction activities such as Public Works Department, Govt construction departments, local bodies or private construction agencies. NBC updated its guidelines in 2016 which is applicable till date.

Wiring norms from NBC 2016 have been explained below which will help you to do wiring in your property  –

• It is preferable to have additional circuit for kitchen& toilet,
• A circuit shall not have more than 10 points of light, fans & 6A socket outlets. And the load of such circuit shall be restricted to 800W & wiring with 1.5 mm² copper conductor.
• If a dedicated circuit is planned for light fixtures, the load of such circuit shall be restricted to 400W with wiring 1.5 mm² copper conductor.
• If a dedicated circuit is planned for 6A sockets, the load of such circuit shall be restricted to 800W or a maximum of 8 numbers socket.
• If a separate fan circuit is provided, the number of fans in the circuit shall not exceed 10.
• Power sockets shall be designed according to load. But in no case, there shall not be more than two 16A outlets on each sub circuits with wire 4 mm² copper conductor with load limit to 1Kw each.
• It is a practice to limit two sockets in a circuit , in both residential & non-residential buildings & to provide single socket on a circuit for a known heavy load appliances such as AC & cooking range etc.
• DB shall be fixed on suitable sanctioned wall and shall not be more than 1.8m from floor level.
• In India, nominal values of low & medium voltage systems are 240V & 415V ac respectively & the frequency is 50Hz.
• For conductor sizes less than or equal to 16mm², only copper conductor cables should be used as Aluminum conductor cables in sizes less than 16mm² cause termination problem leading to heating at terminals & enhance the possibility of a fire.
• Switch & isolator controlling a water heater or geyser should not be located within 1 m from the location of a shower or bath tub, to avoid a person in wet condition. It is preferable to provide the control switch outside the bath room near the entrance & provide an indication at water heater.
• Sockets in kitchen, bathroom toilet, garage etc should not be provided within a height of 1m from the ground level. Similar care has to be taken for installations involving foundations, swimming pools etc.

Light fitting is such areas should be fed at low voltage, preferably though an isolating transformer with a proper earth leakage protection – 100/30mA RCCB/RCD as applicable.

Note – NBC 16 (National Building Code of India 16) provides complete details of electrical system which are required to follow when a building is constructed. Different sections cover different requirement of electrical system.

Wiring related guidelines are given in the link below –