Module 7 · 40 minutes
GFCI and AFCI protection
Understand what these devices detect, where they are used, and how to troubleshoot responsibly.
Learning objectives
By the end, you should be able to:
- Explain the operating concept of GFCI protection
- Distinguish GFCI and AFCI functions
- Identify installation details that affect troubleshooting
GFCI concept
Current leaving ≠ current returning → trip
A GFCI monitors the relationship between current leaving and returning through the monitored conductors. Study line versus load terminals, downstream protection, shared-neutral and multiwire branch-circuit considerations, testing, and troubleshooting.
AFCI concept
AFCI devices are designed to detect electrical signatures associated with dangerous arcing conditions and open the circuit when required. Study where protection is required, combination AFCI concepts, installation instructions, and jurisdiction-specific modifications.
Field check
Explain why a normal circuit overload and a ground-fault current imbalance are different conditions, even though either condition might ultimately interrupt power.