Lights tripping on cold days

[spud1]

Hi everyone,

I have had a strange one going on for a couple of months now.
Same customer calls me back again and again complaining that the B6 amp lighting circuit breaker in their carport sub dist board is tripping.
On the circuit there are 2No. anti-corrosive fluorescent lights inside the carport, 2No. 400W halogen floodlights and 2No. 60W outdoor bulkheads. The anti-corrosives are simply switched and the halogen floodlights come on together from 2No. PIRs wired in parallel and the bulkheads each have their own single PIR activation.
I have done IR tests (Which show no faults) on all circuitry.
I have replaced all fittings and PIRs associated with the circuitry that could be intermittently faulty.
I have done visual inspections on all fittings and accessories to see if water ingress is an issue. (Bone dry throughout)
I have done a load test on the circuit with my clamp meter which shows just over 4 Amps being drawn when all fittings are energized.
Out of interest, I seem to remember in the back of my mind that halogen lamps, when cold, draw more current on initial light up, is that true? If so I'm thinking there may be an inrush current issue on cold days and perhaps a C curve breaker might behave better?

Thanks.

 

[MDJ]

Is the Breaker faulty??

 

[spud1]

No I've replaced the MCB too

 

[Sparky Ninja]

Switching two 400W halogen lamps instantaneously could put a 6A type B over the edge with in-rush.

If the Zs value allows it, try changing to a type C, alternatively see if yo can switch the floods individually.

 

[Octopus]

Just yesterday, I finally found the cause of an intermittent trip in a house - a screw from a curtain track had damaged the cable (probably years ago) and now, after all the rain water ingress allowed the live to pass down the wall (wooden) to the metal back box!