I am laying out a roadway lighting system into a manufacturing facility consisting of several metal poles with cobra head type fixtures. All the poles are to be mounted on concrete bases each with a separate ground rod. The associated ground conductor is bonded to the pole by mechanical means. Due to the length of the the feeder run we are feeding the fixtures at 480V. The fixtures are energized by a photocell controlled contactor in an MCC bucket. The 480V MCC bus that feeds the contactor employs TVSS protection. A question has been raised concerning surge protection on the 480V lighting circuit conductors. If a lightning strike were to occur on the lighting poles, should we be installing surge protection on the load side of our lighting contactor to prevent it from arcing across the contactor contacts when they are open? I have never done this and am not aware that this is a common practice. I was just wondering if anyone has any thoughts on the merits of this approach.
Lightning Surge Protection
- Thread starter mcnichol
- Start date
- Status
barbeer
Senior Member
- Location
- Pinellas County, FL
I would think the answer to your question depends on what equipment you are trying to protect. Ahead of the contactor, leave it on the line side - from the load side out put it on the load side. Furthermore, IMHO lightning will go to Earth before it makes the long voyage "upstream" to your contactor, especially if your electrode system is effective. Thirdly, I was taught that the key to surge protection is redundancy, The more you add, the better the chance for the protection to do it's job.
- Status