CSLB C-46 Solar ContractorPhotovoltaic System InstallationMedium
A solar technician is inspecting the electrical connections of a PV array after a strong wind storm. They notice visible burn marks and melted insulation around a DC connector between two modules. This type of damage is a strong indicator of what electrical fault?
- AGround fault.
- BShort circuit.
- COvercurrent.
- DArc fault.
Show answer & explanationAnswer & explanation
Correct answer: D. Arc fault.
Arc faults occur when a high-resistance connection or a break in the conductor causes current to jump across an air gap, generating intense heat, sparks, and often visible burn marks and melted insulation.
Why the other options are wrong
- A. A ground fault is current flowing to ground, which may or may not cause visible burn marks at the connection point.
- B. A short circuit typically results in immediate overcurrent and tripping of an OCPD, or rapid failure, but not necessarily sustained arcing with visible burn marks at the point of failure unless it was a high-impedance short.
- C. Overcurrent is an excessive current flow, which would typically cause a fuse to blow or a breaker to trip, rather than localized burn marks and melted insulation at a connection point unless the OCPD failed or was oversized.
PV DC Arc Fault
An unintended electrical discharge (arc) between two conductors or a conductor and ground in a DC circuit, often caused by loose connections, damaged insulation, or compromised wiring.
- Generates intense heat and can cause fires.
- Visible signs include burn marks, melted insulation, carbonization.
- Detected by Arc Fault Circuit Interrupters (AFCI) in modern PV systems.
Memory trick: Faults: Arc, Ground, Short, Open