What is Intermediate switch, its construction, working principle and using in different wiring (lighting etc) circuits?
There are four terminals in intermediate switch by which it changes the flowing of current from one circuit to another circuit (fig1). It’s ON and OFF the supply by two ways. The four terminals of intermediate switch is shown in fig 1 label as A, B, C, D. In some cases, the terminal contacts of switch is meet terminal A with terminal C and terminal B meet with terminal D as shown in fig 1 a.
click image to enlarge.
In other cases , the terminal contacts of switch is meet terminal A with terminal B and terminal C meet with terminal D as shown in fig 1 b.
When the knob of the switch is UP, then the vertical contacts are meeting (i.e. AC and BD as shown in fig 1a). And when the knob is DOWN, then the Horizontal contacts are meeting (i.e. AB and CD as shown in fig 1b).
This kind of switch is used in a hall or big rooms or Godown where different lamps are require to ON from different places. Moreover, in a multistory building, the lamp at ground floor in car parking shade can be controlled or ON or OFF from any floor by made of intermediate switch circuit.
In Fig 2, a lamp is controlled from three different places by using two, 2-way switches and one intermediate switch.
In fig 3 a lamp is controlled from six different places by using two, 2-way switches and four intermediate switches.
fig 2...click image to enlarge
Key Point: You can control a lamp from more different places by adding more intermediate switches.