Protecting Contacts from Damage

Reed relays are extremely reliable, but their contacts are small. Switching certain loads without protection can cause welding or early failure.

Capacitive Loads (Inrush Current)

When switching a line with significant capacitance (e.g., long cables), a massive current spike (“Inrush”) occurs at the moment of closure.
Solution: Place a small resistor in series with the contact to limit the current.

Inductive Loads (Back EMF)

When breaking an inductive load (like a solenoid or motor), the collapsing magnetic field generates a high voltage spike (Back EMF) that can arc across the opening contacts.
Solution: Use a diode (DC) or RC Snubber (AC) across the load to clamp the voltage spike.