Run of Parking Lot lights with trip after an hour

Status
Not open for further replies.

amer28

New member
Greetings and thanks for any help.

Do sign and parking lot lighting and once in a while we'll get a call for a breaker tripping a circuit of signs or parking lot lighting after an hour or more of running - not a dead short or immediate trip. We will usually break circuit in half, turn on and wait for trip. If trip, then know that side is culprit, break in half again, etc until we isolate problem. As an example, eight parking lot lights in a row, power coming in from left most pole. Disconnect 4 on right side. If left side trips breaker (after an hour in the heat) assume one of left side ballast failing and tripping out after overheating. Break same left side into now 2 fixtures connected to power and now six disconnected from power and continue to isolate until get to culprit.

Problem with this is #1 - the waiting between trips and #2 - once in a very long while go through whole test and nothing trips ie - reconnect all and does not trip out so you are stuck with a lot of hours and no fix. Could be breaker but would you just swap that out first without testing?

Any ideas - and again, thanks for any help.
 

mxslick

Senior Member
Location
SE Idaho
First off, welcome to the forums. You'll find a lot of helpful and colorful people here. :grin:

There are several threads on here in regards to similar issues, but I'll save you the trouble of reading them all to make this suggestion:

Install in-line fuse holders in the base of each light pole..I believe the common fuse size will be 6 amps.

This will find your problem easily as the one fixture that's causing the problem will ideally blow the fuse before the breaker trips.

Now if the breaker is loaded to say 75% or more then there is a chance that the breaker may still trip but hopefully the fuse will have blown too.

Others will chime in soon with more suggestions.
 

quogueelectric

Senior Member
Location
new york
Individual fusing was always my prefered method of this common problem. You can tell a lot about what is going on with a good clamp on ammeter also. This is much faster and safer than disconnecting everything. Figure what one lamp draws and do some simple math. Good luck and be careful this is an easy one to get hit on be wary of energized poles to ground also.
 

Electric-Light

Senior Member
How old are they? High power factor ballasts usually have a parallel capacitor who's presence does not affect operation if there's plenty of room left in the circuit, so failure often go undetected.

If the circuit is designed with the design power factor in mind and you have a lot of fixtures with failing PF capacitor, then you'll have excessive line current that might trip the breaker.

A power quality analyzer should be hooked up and see if the load power factor is what they should be.
 

GlennG

Member
Location
Hicksville, NY
I had the same problem with the parking lot lighting in one of the beaches that I maintain. After being on for a half hour or so the breaker would trip out. The problem was eventually traced back to a bad cable between the second to last and last pole on the line, and like in the case you are describing it was a small leakage to ground, that takes time to present itself. Also maybe the reason for it not tripping sometimes is related to the amount of moisture in the ground on different days. In my case time was no issue because I work for the Town that I live in, and government doesn't use the time is money theory, but I will agree that it is extremely frusterating troubleshooting an intermittent problem.
 
Status
Not open for further replies.
Top