Definition
An electrical circuit that combines both series and parallel wiring within the same circuit. Some components are connected end-to-end so the same current flows through each (the series portion), while other components are connected across common points so they share the same voltage (the parallel portion).
Plain English
A circuit that has parts wired one after another and other parts wired side by side, all working together as one circuit.
Context Anchor
Seen in aircraft electrical system diagrams, maintenance manuals, and troubleshooting discussions for lights, instruments, and other powered equipment.
Derivation
Series comes from the Latin 'series' meaning a row or chain — components in a row, one after another. Parallel comes from the Greek 'parallelos' meaning side by side. A series-parallel circuit literally has parts arranged both in a chain and side by side.
Why Pilots Care
Correct identification of this layout is required to predict voltage drops and current flow when diagnosing aircraft electrical faults.
Analogy
Think of water flowing through pipes. One section may force the water through valves one after another, while another section splits into two pipes and then joins again. A series-parallel circuit is the electrical version of that mixed layout.
Intuition Check
Do not assume a series-parallel circuit is simply two separate circuits. It is one circuit that contains both one-after-another connections and split-path connections.
Example Sentence 1
The instrument panel lights and their dimming control form a series-parallel circuit, so the lamps share voltage while the rheostat controls current to all of them at once.
Example Sentence 2
During preflight, the pilot verified that the battery charging circuit followed a series-parallel arrangement before starting the engine.