Which precaution helps ensure reliable connections in circuits?

• A. Always check that connections are clean
• B. Switch off the current when not measuring
• C. Check polarities before closing the switch
• D. Tap the meter to avoid sticking

Answer: (A)

Clean, oxide-free contact surfaces are essential for reliable conduction. Dirt, oil, or corrosion on metal joints can form insulating films and increase contact resistance, leading to intermittent connections or voltage drops. When connections are clean and terminals are pressed firmly to ensure good metal-to-metal contact, the circuit has a stable path for current and operates more reliably.

Switching off power when not measuring helps safety and protects components, but it doesn’t directly improve how well a connection conducts. Checking polarities before closing the switch is important for correct operation and to avoid damage to polarized components, but it doesn’t address the physical reliability of the connection itself. Tapping the meter is likely to disturb the contact and can introduce noise or loosen connections, so it’s not a good habit.

So, keeping connections clean and ensuring good contact is the best precaution for reliability.