Lighting Contactors

7 replies [Last post]
WPratt's picture
Joined: 2013-11-13

We have a lighting contactor system with a switch in another area of the building. The switch can be "All On"/"All Off/"Local Control". This switch controls several circuits. We are using 120V for the switching of 277V fixtures.
Whenever we switch to "All Off" everything is good. When in "Local Control" we are able to turn off lights at their individual locations.
The problem is that whenever we take the switch from the "All Off" position to "Local Control" or "All On", one of the 277V breakers trips. After reset, the 277V breaker also trips when turning on that same circuit at the individual switches while in "Local Control".
We have tested the breaker, the contactor, and all the switches. Do you have a suggestion as to what we should explore next?

sparky377's picture
Joined: 2013-10-07

Without a complete description of the control and load circuits and how they are connected, a wiring schematic would be best, it is impossible to troubleshoot your problem. At a minimum, it sounds like you may have interconnected the neutral conductors of your 120V and 277V systems.

djr3203's picture
Joined: 2013-11-18

I agree with Sparky377. However, I have read about CBs tripping due to inrush current on some LEDs. I believe this has to do with the inrush charging current of the capacitor on the rectifier stage. Some drivers are designed better than others. I would meter the circuit when you switch the lights on and see what kind of inrush you are getting.

jkuennen's picture
Joined: 2013-11-07

If the 277 volt breaker trips immediately when you turn on a local switch, it sounds like you may have a short in that lighting circuit. Use the divide and conquer method to find it.

agrisib's picture
Joined: 2013-11-08

What color are the lights?

mc5w's picture
Joined: 2013-10-09

Electronic ballasts have absurdly high inrush currents regardless of whether they are fluorescent or LED. There are a number of ways to fix this such as by using capacitor contactors which have a set of early make contacts that engage a bunch of starting resistors before the main contacts close. Also, you might need to hook up the contactors with 3 poles in series with each other so that the ballasts does not pull a pronged arc through the contacts when ballast tries to live on 110V tries and creates a 167V arc in the contactor.

guaranteed's picture
Joined: 2014-04-20

Whenever we switch to "All Off" everything is good. When in "Local Control" we are able to turn off lights at their individual locations.

Nilsson121's picture
Joined: 2015-05-06

I agree with jkuennen. You should use divide and conquer method as this can be effective for such problems.

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