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street lighting 22 March 2026 by Benlight crew

Why your street light keeps tripping at 2 a.m.

A two-minute fault-finding routine that catches 80% of the common causes before the technician arrives. Save the call-out fee, and save the time.

Four street lights coming on at dusk along a rural road.

If you’ve got a high-mast or compound light that trips its breaker overnight and then resets fine in the morning, the cause is almost always one of four things. You can rule out three of them in two minutes with a torch and a multimeter — saving the call-out fee and the wait.

1. Moisture ingress at the gland (most common)

Overnight temperatures drop and condensation forms inside the head. By morning it’s evaporated and the leak is invisible. Open the head, look at the gland seal where the cable enters — if there’s a rubber boot, check it hasn’t perished; if it’s just self-amalgamating tape, re-do it. Replace the head gasket while you’re up there.

2. A failed surge protection device (SPD)

A nearby lightning strike can punch a hole through an SPD and leave the rest of the circuit working — until the next surge hits the now-unprotected gear and trips the breaker. Look at the SPD indicator window (a red flag means it’s spent). They’re cheap; swap proactively after any storm season.

3. The driver’s electrolytic cap is leaking

LED drivers fail differently from old ballast gear — they don’t dim, they just refuse to start one night. If the head clicks on for a second and trips, it’s almost always a driver fault. Take it down, look for any swollen or leaking capacitors on the PCB. Replace the driver as a unit — don’t try to swap caps unless you really know what you’re doing.

4. A loose neutral upstream

The hardest of the four to diagnose, and the most dangerous. If the neutral is loose at the panel or at the supply, voltage on the live can swing wildly — the light works in the day when load is balanced, then trips at night when load drops and voltage spikes. Check the panel termination torque (manufacturer spec is usually 3.5–4 Nm for a typical screw terminal). If that’s fine, you need a sparky to chase the supply side.

The two-minute routine

  1. Open the head, eyeball for moisture or melted plastic. 30 seconds.
  2. Check the SPD indicator. 15 seconds.
  3. Disconnect the driver, ohm out the LED array (should be a few kΩ open-circuit). If the array is fine but the driver is dead, swap the driver. 45 seconds.
  4. Re-energise, watch with the panel-meter app or a clamp meter — if voltage swings as the light kicks on, you’ve got a loose-neutral upstream. 30 seconds.

Most overnight-trip jobs are #1 or #2. If it’s #3 or #4, give us a call — we keep matched drivers in stock for the panel types we install, and we can swap one in 20 minutes.