Domestic Wiring Chapter 1

 Domestic Wiring

The practice of domestic wiring has been standardised. 

Any deviation for these practices may lead to untoward incident like short circuits or electric shock to personnel e.g.

It is mandatory to place a fuse wire in the phase wire (live wire). 

An attempt to put it in the natural may create problem after the fuse blows offdue to short circuit. 

Proper material should be used for laying the domestic wiring depending upon the environment, location, safety to personnel, to equipments etc.

TYPES OF DOMESTIC WIRING

Following are the different types o fdomestic wiring :

✓ Cleat wiring

✓ Wooden casing and capping wiring

✓ TRS or Batton wiring

✓ Surface conduit wiring

✓ Concealed conduit wiring

The above listing is in the direction of increasing cost ; temporary/permanent wiring and better appearance. We discuss them in brief as follows :

Cleat Wiring

In this system of wiring the cables are gripped and supported between cleat made of porcelain.

These cleats are made in two halves; the lower part is grooved to accommodate, the cable and the upper part is put over it. 

After the cable is put-between the cleats, these are then screwed on wooden plugs also known as gutties. 

The gutties should first be fixed into the wall at regular intervals of about 50 cm. 

The screws used are of size 38 mm length. For 250 volts supply, the cables will be placed 2.5 cm apart centre to centre for single core cables. 

Only one cable is passed through each groove of the cleat. 

While screwing too much pressure should not be applied so that its insulation remains intact. 

The cables normally used in cleat wiring are VIR (Vulcanised India rubber) cable, PVC cables etc. 

In this system of wiring sharp bends and undue twisting should be avoided. 

Also, whenever cable has to pass through walls, floors or any other concealed location, the conduit pipe of suitable length should be used for that portion of wiring. 

Cleats for two wires

The advantages and disadvantages of cleat wiring are:

Advantages :

The installation and dismentling is simple and fast and hence is very useful for

temporary wiring.

The cable can be inspected easily and if there is any problem with the wiring the same

can be rectified without much problem.

Disadvantages :

The appearance of the wiring is not good.

It cannot be used in damp places.

As the wiring is exposed to atmosphere, its life span is short.

Wooden/PVC Casing and Capping Wiring

This method of wiring is one of the very old method and is in use even as of now. 

This system is suitable for the voltages installations using VIR or PVC cables.

The Casing and Capping form two parts of the wooden or PVC, the Casing and Capping

have grooves. 

The cable is placed in the grooves ofthe Casing and this is then covered by capping. 

The Capping is fitted to the casing with the help of screws of 12. 7 mm length. 

The Casing and Capping should be made ofteak wood.

Two casing shaped for straight joint A finished straight joint.

Two casing shaped for straight joint.

The casing should be spaced from the wall by means of small porcelain blocks or disc

insulators not less than 6.5 mm thick so that direct contact to the wall is avoided and hence it is protected against dampness of wall.

The following are the advantages and disadvantages ofthis method ofwiring.

Advantages :

✓ It is relatively cheaper as compared to conduit but costlier as compared to cleat-wiring

✓ Short-circuit of wire i.e. between phase and neutral is avoided as the two are placed in different grooves.

✓ Physical inspection of wiring makes it simple to carry out any repair if required (by

opening the capping).

✓ PVC casing capping gives better look and is economical as compared to wood.

Disadvantages :

✓ In case of a short-circuit, there is risk of fire (use of wood or PVC).

2. Normally not recommended for damp places.

Toughened Rubber Sheath {TRS or CTS) or Batton Wiring 

In this case the cables are carried on seasoned teak wood perfectly straight and well varnished teak wood batton of thickness not less than 1 cm. 

The cables are fixed on the batton by means of tinned brass or aluminium link clips already fixed on the batton with small nails before laying cables. 

The battons are fixed to the walls by means of gutties with countersink headed wooden screws. 

The screws are to be fixed on the batton at an interval of about 75 ems. 

The minimum width of batton is 13 mm for two wires. It is found suitable where acids and alkalies are stored.

The various sizes ofbatton available are 13, 19, 25, 31, 38, 44 and 50 mm width. 

Depending upon the no. of cables to be run, a suitable size ofbatton should be used.

The main advantages and disadvantages of this wiring are :

✓ Easy to instal and economical as compared to casing cappings or conduit wiring.

✓ Easy to detect fault if any and has good appearance.

✓ Relatively good life span.

Disadvantages :

✓ Not suitable if exposed to sun and rain or places where dampness exists.

✓ Risk offire high.

✓ CTS stands for Cab Type sheathed.