How do we use a Megger?
Other than a multimeter, a megger is another device whose use is definitely appreciated by any lover of electronics. A megger is also known as an ohmmeter and it comes in handy when you want to measure the insulation resistance of electrical machinery or system.
The megger can be mechanically operated using the hand crank DC generator or battery operated and it gives the direct reading in ohms which is why it is referred to as an ohm meter.
So as to use a megger, you should first power off the circuit you want to test. If you are uncertain of which breakers or fuses are controlling the circuit, you should turn off the main breaker.
You should then isolate the wires you want to test from any portion of the circuit. In some cases, the circuit may be too complex in which case you’ll be needing special tools to have the wires isolated.
Having removed all the electrical connection from the wires, expose the wire ends by simply revealing the bare copper connection points. Insulate the conductor so as to protect it from accidental shorting by covering one end of the wires copper connection with a nut. Other than accidental shorting, you could also risk getting false readings if you don't do this.
Have the positive end of the megohmmeter to the other end of the circuit which should be the bare copper wire that is being tested. Connect the ground wire of the meter to that of the electrical system which should be the main electrical panel box.
You should then switch the meter to the on position. Most megohmmeters have a charge button that is situated at the face of the meter. Press this button and observe the meter. If the reading is greater than 999 meg, then it is perfectly insulated.