Circuit Breaker used as current limiting device to meet exception allowed by 220.43(B)

[steveshow]

"For track lighting in other than dwelling units or guest rooms or guest suites of hotels or motels, an additional load of 150 volt amperes shall be included for every 2 ft. of track lighting or fraction thereof. Where multi-circuit track lighting is installed, the load shall be considered to be divided equally between the track circuits. Exception: If the track lighting is supplied through a device that limits the current to the track, the load shall be permitted to be calculated based on the rating of the device used to limit the current."

I have encountered several electrical designers/ P.E.s that show hundreds of feet of track lighting, with no current limiter listed on the fixture schedule or called out in the manufacturer cut sheets. They argue that the circuit breaker meets the exception of being a current limiting device. My first argument is that a 20 amp (or any amp rating, for that matter) circuit breaker will not protect the track from overload. None of them can wrap their heads around the fact that human nature of "non-qualified personnel" is to clip more and more track heads on a track, until the desired lighting level is attained, potentially overloading the track. There hasn't been a valid argument against this. My second argument is if the circuit breaker is the current limiting device, why is the exception mention at all? The circuit would be covered by 240.4. (It's not, because 240.4 addresses conductors, not devices, but again, this point is lost on them. Any thoughts? I have not been able to find any discussion on this topic, either here on the internet in general.

 

[david luchini]

Any thoughts?

My thought is that the electrical designers are correct. The circuit breaker will protect the track against overload the same way it will protect the branch circuit conductors supplying the track against overload.

And a track current limiting device is just a smaller amperage circuit breaker.

 

[curt swartz]

The current limiters are not to protect the track, the branch circuit breaker does that . Current limiters limit the energy the lighting system can use to comply with energy codes.

 

[don_resqcapt19]

The rule you are talking about is in 220.43(B). Article 220 is the load calculation rule and has nothing to do with the actual overcurrent protection of the track. It simply permits you to base the track lighting load for the purposes of calculating the service and feeder loads on the rating of the current limiting device. If you do not have a current limiting device, you must use a load of 150 va for every two feet of track for the purpose of calculating the service and feeder loads.

The actual overcurrent protection is covered in 410.151(B) which says, "Lighting track shall be supplied by a branch circuit having a rating not more than that of the track."

 

[steveshow]

I now realize that I got two issues mixed up. 220.43(B), like all parts of 220 is in regard to calculation only, not protection. I suppose my question should be is it OK to use the branch circuit OCPD as the current limiter allowed exception to 220.43(B), not an additional track limiter? I still think it is not. I came across a recent project that had around 75 ft of track. A 20 amp breaker was present, and the calculated load was indicated to be 1920VA, and no track current limiters. As stated above, without the current limiter, what is to keep the end user from installing more track heads on the track after installation and exceeding the load that was originally calculated?

 

[don_resqcapt19]

I now realize that I got two issues mixed up. 220.43(B), like all parts of 220 is in regard to calculation only, not protection. I suppose my question should be is it OK to use the branch circuit OCPD as the current limiter allowed exception to 220.43(B), not an additional track limiter? I still think it is not. I came across a recent project that had around 75 ft of track. A 20 amp breaker was present, and the calculated load was indicated to be 1920VA, and no track current limiters. As stated above, without the current limiter, what is to keep the end user from installing more track heads on the track after installation and exceeding the load that was originally calculated?

The load calculation rule does not specify the type of current limiter, and based on a 20 amp breaker, I don't see any issue using a calculated load of 1920 VA.

 

[drktmplr12]

As stated above, without the current limiter, what is to keep the end user from installing more track heads on the track after installation and exceeding the load that was originally calculated?

the circuit breaker, when it trips after the customer adds too many lights, just like a receptacle in a dwelling. the calculation is just that, a calculation. if your concern is that the load calculation isn't valid because they loaded up their track with 18 amps worth of lights instead of 16, I assure you there is enough load diversity in the system to absorb that.

if they add so many lights to all the tracks and run the dryer and washer while leaving the hot water on and thermostat at 50 F, well maybe they just deserve to deal with tripping circuit breakers.