WiremanWireman · Parking lot or pole light out: troubleshooting for electricians · 2023 NEC ·
Parking lot or pole light out
One pole dark, a whole row out, cycling at night or burning all day. Control, base fuses, underground or the head.
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How it works
Site lighting usually runs at 208, 240, 277 or 480 V on underground circuits in conduit. A lighting contactor at the panel, switched by a photocell or a time clock, turns a whole group of poles on and off. Each pole base has a handhole with splices and often in-line fuse holders that protect that one head. The head has a lamp with a ballast and igniter (metal halide or high-pressure sodium), or an LED driver. Whether one pole or a whole circuit is out tells you whether to start at the panel or at the pole.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- What’s out?
- Every pole on the circuitTest: Check the breaker and the lighting contactorExpect: Circuit voltage on both the line and load sides with the contactor called closed.
- The breaker is trippedA fault on the lighting circuit
- Line side good, load side deadThe contactor or its control
- Voltage leaving the panel, poles still darkAn open conductor between the panel and the first pole
- One poleTest: Measure at the pole baseExpect: Circuit voltage on the incoming conductors and through each fuse holder.
- No voltage at the baseAn open between this pole and the previous one
- Voltage in, not through a fuseA blown base fuse
- Voltage through the fusesWhat kind of head is it?
- Metal halide or high-pressure sodiumHID lamp, igniter, capacitor or ballast
- LEDLED driver, surge module or board
- Cycles on and off at nightWhat kind of lamp is cycling?
- High-pressure sodiumAn end-of-life HPS lamp
- Metal halide or LEDPhotocell seeing light, or overheating
- Burns during the dayA failed photocell, stuck contactor or wrong control setting
- Every pole on the circuitTest: Check the breaker and the lighting contactorExpect: Circuit voltage on both the line and load sides with the contactor called closed.