breaker tripping ?

[papa]

480 volt 30 amp breaker for parking pole lights is tripping after about one hour. Lights are 480 and feed though a contactor . Ohmed each leg to ground and phase to phase seems ok. Amps are L1-6, L2-7, L3-6. Any suggestions?

 

[SG-1]

1.You could have a bad breaker. ( Might try a fall of potential test across the breaker. )

2. You may need to continously monitor the current to the lights, because at some point it is great enough to trip the breaker.

3. Megger Time. The conduits could be flooded.

4. The insulation in one of the lights may be breaking down when it reaches a certain temperature. ( Continously monitor the current to see which phase(s).)

 

[jeremysterling]

1.You could have a bad breaker. ( Might try a fall of potential test across the breaker. )

2. You may need to continously monitor the current to the lights, because at some point it is great enough to trip the breaker.

3. Megger Time. The conduits could be flooded.

4. The insulation in one of the lights may be breaking down when it reaches a certain temperature. ( Continously monitor the current to see which phase(s).)

I saw this happen where the answer was: 3. flooded conduits.