Methods of Wiring

There are two methods of wiring known as joint box system (or Tee system) and loop-in system.

(a)    Joint Box or Tee System: In joint box system the connections to the lamps are made through joints made in joint boxes by means of suitable connectors or joint culouts. In this method though there is a saving in the quantity of wire or cable required but the


Same is offset by the extra cost of joint boxes. The other disadvantage of T-connections is that the number of T-connections made in a wiring system results in weakness if not property made. Now-a-days the use of this system is limited to temporary installations only as its cost is low,

(b)    Loop-in system: This system is universally employed for connections of various lamps or other appliances in parallel. In this system when a connection is required at a light or switch, the feed conductor is looped-in by bringing it direct to the terminal and then carrying it forward again to the next point to be fed, as shown in. The switch and


light feeds are carried round the circuit in a series of loops from one point to another until the point on the circuit is reached.

The phase or line conductors are looped either in switch board or box and neutral conductors are looped either in witch board or from light or fan. Line or phase should never be looped from light or fan.

In no case joint is to be made in the run of wire or cable.
The advantages and disadvantages of loop-in system are as follows:

Advantages: 1. Joint boxes are not required.

2. In loop-in-system no joints are concealed beneath floors or in roof spaces. As they are made only at outlets so they are accessible for inspection and opening out merely by removing the fitments concerned. Hence fault location is easy.

Disadvantages: 1. Length of wire or cable required is more and voltage drops and copper losses are therefore more.

2. Looping in-switches and lamp holders is usually difficult.