Here's why:
* Ohmmeters measure resistance. Resistance is the opposition to the flow of electrical current.
* A live circuit has current flowing through it. If you connect an ohmmeter to a live circuit, the current will flow through the ohmmeter, potentially damaging the meter and/or causing a dangerous electrical shock.
* By disconnecting the power source, you ensure there is no current flowing. This allows you to safely measure the resistance of the circuit components without any interference.
Important Note: Always use caution when working with electricity. If you're not comfortable with electrical safety procedures, seek help from a qualified electrician.
