Because the building that I’m working in was built about 50 years ago, I’m coming across old electrical equipment. As an example, one exhaust fan is being controlled by a GE 200 Line Combo Motor control with fusible disconnect.
This combination disconnect motor starter is housed in a box with a hinged cover.
It may be old but it still functions correctly.
The power comes in through a knockout in the back and lands on the top terminals of the fusible disconnect part. Whenever I land power on a switch I land the line on the top terminals. From the load side of the disconnect, pass the fuses, we wire to the line terminals of the contactor, the terminals on top.
Then, an additional wire landed in the ‘A’ phase line terminal of the contactor goes to the COMMON terminal on a RIB relay, another wire goes from the RIB’s NC terminal to one side of the contactor coil. The other side of the contactor coil has a wire coming from the ‘B’ phase contactor line terminal. This means when the disconnect is closed the fan will be on.
Now, with 24V from the FA control relay, the fire alarm system can shut off the fan. Here is a diagram to clarify the wiring.
Comments, criticism, tips are always welcome.
Buddy,
The San Francisco Electrician
