What is circuit termination?
Where a series lighting circuit starts and ends — both cable ends land at the CCR, so the loop has no far end.
Circuit termination is where a series lighting circuit starts and ends. Both ends of the primary cable are terminated at the CCR output terminals: the cable leaves one terminal, runs through every isolation transformer primary in series, and returns to the other. The loop has no far end.
A loose, damaged or unterminated end opens the loop, so every lamp goes out, and a poor connection can overheat. Terminations are made with the circuit isolated, locked out and proved dead, insulated, identified, and checked by continuity and insulation tests. This is different from cable termination, the physical work of connecting a cable end that happens at many points around the loop.
- Route. Run the primary cable out through the circuit and back to the CCR.
- Isolate. CCR off, locked out and tagged; confirm the circuit is dead.
- Terminate. Connect both cable ends at the CCR output terminals.
- Insulate & identify. Protect each connection and label the circuit and ends.
- Test. Continuity and insulation resistance on the closed loop.
- Record. Log the readings against the commissioning baseline.
Frequently Asked Questions
Q1What is circuit termination in a series lighting circuit?
The points where the series loop starts and ends. The two ends of the primary cable are terminated at the CCR output terminals, and every isolation transformer primary is connected in series in the cable between them.
Q2Where does a series lighting circuit terminate?
At the CCR. A series loop has no far end: the cable leaves one CCR output terminal, runs through all the transformers and returns to the other output terminal, so the circuit is closed at the CCR.
Q3Why can't a circuit end at the last fixture?
Current needs a complete path. A cable that ends at the last fixture leaves the loop open, so no current flows and every lamp on the circuit goes out. The cable has to return to the CCR to close the loop.
Q4What happens if a termination is loose or fails?
The loop can open, giving an open circuit with all lights out, or the poor connection can overheat or arc at the terminal. A loose end on an energised circuit is also a shock hazard, so terminations must be secure, insulated and protected.
Q5How is a termination checked?
With the circuit isolated, locked out and proved dead, by inspecting the connection and its insulation, then testing continuity and insulation resistance of the loop and comparing the readings with the commissioning baseline.
Q6How is circuit termination different from cable termination?
Circuit termination is where the loop starts and ends at the CCR. Cable termination is the physical work of connecting a cable end to a connector, joint or terminal, which happens at many points around the loop, including at the CCR.
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