Roadway Lighting and Art 210.4(B),from the 2008 Edition of the NEC

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Granja

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My question concerns having a multi-pole breaker as a disconnecting means for multi-wire branch circuit that feeds roadway lighting. In this case, where a sequential line of poles/fixtures would be circuited with alternating phases (A, B & C - 277V line to neutral); Art 210.4(B) dictates that three line-to-neutral circuits must be protected by a 3-pole breaker instead of three separate single-pole breakers.This presents a dilema implementing the standard for circuiting with alternating phases.

With the single-pole breaker standard; when/if a breaker trips only every third fixture will extinguish, thereby enhancing public safety by keeping 2/3rds of the amount of light remaining for the roadway in a given sequence.

An example might be when a car hits a pole and potentially trips the 3-pole breaker, taking out the lights in 2500 ft sequence - thereby providing less light for emergency personnel, etc. It seems that there should be an exception to Art 210.4(B) for Roadway Lighting circuited in this fashion.

Otherwise, the municipality would have to endure the added cost for running separate neutral conductors and related costs.
 
By my way of thinking, if the municipality is concerned over losing all the lights, then they need to spend the extra money for separate neutrals. It is a matter of one safety consideration weighed against another safety consideration. A maintenance person working on one circuit that is part of a MWBC can be at risk of electrocution, under certain conditions, if all of the circuit breakers associated with that MWBC are not turned off.

Welcome to the forum.
 
Roadway Lighting and Art 210.4(B),from the 2008 Edition of the NEC

Thanks for the prompt response Charlie. We agree, it IS trading one safety consideration against another, without enduring the cost of separate neutrals for 5 miles of Roadway.

But a reasonable exception might be the utilization of the MCB of the street lighting service panel or the HOA switch that's ahead of contactor assembly for maintenance purposes. We can certainly assume maintenance personnel would be qualified electricians. That, along with signage to indicate that these devices shall be disengaged prior to maintenance would seem (to me) to be a basis for an exception.
 
Granja said:
Thanks for the prompt response Charlie. We agree, it IS trading one safety consideration against another, without enduring the cost of separate neutrals for 5 miles of Roadway.

But a reasonable exception might be the utilization of the MCB of the street lighting service panel or the HOA switch that's ahead of contactor assembly for maintenance purposes. We can certainly assume maintenance personnel would be qualified electricians. That, along with signage to indicate that these devices shall be disengaged prior to maintenance would seem (to me) to be a basis for an exception.
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90.4 Enforcement.
By special permission, the authority having jurisdiction may waive specific requirements in this Code or permit alternative methods where it is assured that equivalent objectives can be achieved by establishing and maintaining effective safety.


Pete
 
I get this argument all the time when ever this issue comes up.

I simply tell them it's not my job to discuss the philosophy of the code, it's simply my job to enforce it.

We're a little behind here so I remind contractors that if they want to put in a chage, that the 2011 is already written and I'm guessing that the 2014 is pretty much on it's way to being done too.
 
cowboyjwc said:
I...
We're a little behind here so I remind contractors that if they want to put in a chage, that the 2011 is already written and I'm guessing that the 2014 is pretty much on it's way to being done too.
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The proposals for the 2014 are not due until 5pm on the first Friday of November of this year.
 
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