exterior lighting?

[Bill Marino]

Is it a requirement for exterior lighting fixtures, operating above 150V to ground, to have supplemental overcurrent devices? Such as fuses on the ballast wires. We have 30ft poles, Metal Halide 400W @ 480V. If a ballast shorts to ground, as what happened a week ago, it tripped out the main 480V 250A feeder breaker in our load center, not the branch circuit breaker. I've seen fuse holders located in the hand holes in other locations where the outside lighting was operating at 480V so I assumed it was required. Is it in the 2011NEC?

 

[iwire]

Not a requirement, just a design choice so a shorting ballast does not take out the circuit.

The fact you lost the main would make me look at the GFP settings on the main.

If you download the ballast makers cutsheet for the ballast you are using they will often recommend a fuse size to use. Often in the 4 to 6 amp range.

 

[kwired]

Not a requirement, just a design choice so a shorting ballast does not take out the circuit.

The fact you lost the main would make me look at the GFP settings on the main.

If you download the ballast makers cutsheet for the ballast you are using they will often recommend a fuse size to use. Often in the 4 to 6 amp range.

250 amp breaker probably doesn't have GFP, you maybe meant magnetic trip setting?

 

[iwire]

250 amp breaker probably doesn't have GFP, you maybe meant magnetic trip setting?

GFP not required directly by code but finding more and more with GFP to handle coordination issues.

 

[kwired]

GFP not required directly by code but finding more and more with GFP to handle coordination issues.

Sounds like it just complicated issues for OP

 

[mgookin]

So why didn't the branch circuit breaker trip guys?

 

[kwired]

So why didn't the branch circuit breaker trip guys?

Because it either had:

A, ground fault protection that was set for lower trip level then the branch level device

B, feeder/service overcurrent device had adjustable magnetic trip and was set lower then magnetic trip of the branch device

C, if nothing was adjustable, poor selection/coordination of components - the feeder/service overcurrent device reached a trip point in it's trip curve before the branch device reached it's trip point.

 

[mgookin]

Because it either had:

A, ground fault protection that was set for lower trip level then the branch level device

B, feeder/service overcurrent device had adjustable magnetic trip and was set lower then magnetic trip of the branch device

C, if nothing was adjustable, poor selection/coordination of components - the feeder/service overcurrent device reached a trip point in it's trip curve before the branch device reached it's trip point.

Thanks kwired. :thumbsup: