Where are overload protection devices placed in a wire diagram relative to circuit protection?

Where are overload protection devices placed in a wire diagram relative to circuit protection?

• A. After circuit protection in parallel with load leads
• B. In series with the line leads after protection
• C. Before circuit protection in series with the line leads
• D. At the power source

Answer: (C)

Overload protection must be in series with the load so it can break the circuit if current exceeds the safe limit. When a device sits in series, every ampere flowing to the circuit goes through it, so it can detect the excess current and open the circuit to stop damage. If it were placed after other circuit protections, or in parallel, it wouldn’t reliably interrupt the current to the load when an overload occurs, and faults could bypass it or be addressed only after other protections act. Placing it on the line side, in series, ensures it is the first line of defense and sees the full supply current, providing effective protection.

Overload protection must be in series with the load so it can break the circuit if current exceeds the safe limit. When a device sits in series, every ampere flowing to the circuit goes through it, so it can detect the excess current and open the circuit to stop damage. If it were placed after other circuit protections, or in parallel, it wouldn’t reliably interrupt the current to the load when an overload occurs, and faults could bypass it or be addressed only after other protections act. Placing it on the line side, in series, ensures it is the first line of defense and sees the full supply current, providing effective protection.