Lighting load

[hillbilly]

I've been working on a commercial job and installing lighting fixtures in a commercial art showroom, 95% of which are track lighting fixtures. During my initial design the Customer/General/Owner gave me a sketch showing number and length of fixtures. I installed homeruns using 75 watts/lin.ft of track. We're nearly complete and a problem has surfaced. At this stage he wants to add more track surface. All my lighting homeruns are #12 90C CU on 20A breakers. In my engineering I used 16A load (80% due to continuous load) for each home run. My question is since the #12 amperage is already derated by the code, I'm on 20A breakers and my terminals are rated at 75C, can I safely (and within code) load each lighting circuit to 20A.
Thanks in advance
steve

 

[ryan_618]

Re: Lighting load

Notice that the article that governs track lighting ciruit calculations is for feeders and services. I don't have my NEC here, but look in the index and find lighting track, then find something in article 210 that governs the track lighting BRANCH circuit requirements. I believe it states that the OCPD cannot be higher than the rating of teh track, but thats all it says. I would be willing to bet that your tracks are not anywhere close to 20 amps if you did the branch circuits at 75W/ft.

 

[hillbilly]

Re: Lighting load

All of my track fixtures are rated 20A. Sorry I didn't post this the first time.
Steve

 

[ryan_618]

Re: Lighting load

After reading my reply I realize that I wasn't very clear. What I meant was that if you assumed 75W/ft for your branch circuits, put an ammeter on the actual load or bust out Ohms' law and you probably aren't at 20 amps (or even 16). I hope this can help you out, otherwise I see nothing but another circuit.

 

[hillbilly]

Re: Lighting load

What I really want to know is how much track load can I put on each homerun. I'ver got the feeling that when I leave more fixtures will be added and it will be maxed out. I don't want to exceed a target 75 watt/lin.ft. of track which will keep me within code. Do I have to use the 80% continuous load (16A per homerun)? or can they be loaded to 20 amps?
steve

 

[ryan_618]

Re: Lighting load

Originally posted by hillbilly:
Do I have to use the 80% continuous load (16A per homerun)?

Yes

 

[iceman2610]

Re: Lighting load

You are tied to the 16A. However, the 75W/lin ft. may not be realistic. this would allow the owner to have a 75W bulb in each fixture every 12 inches. The branch circuit rating should be based on the actual maximum expected load. Using a 75W flood, (of corse this would depend on the distance from the target area the bulbs are located) the fixtures will probably be located 3 to 4 feet apart. Otherwise, a person would need a welding helment when entering the room. lol.

Hope this helps. I am only speaking from my expierence of track lighting. I do not know your exact application.

 

[iceman2610]

Re: Lighting load

Ryan,

you were quick on the draw. Your pose beat mine.LOL

 

[ryan_618]

Re: Lighting load

Iceman: I may have beat you on the draw, but I think you did a better job than me in trying to explain exactly what I was thinking! Good post

BTW: Are you still playing volleyball with maverick?

[ September 07, 2003, 09:59 PM: Message edited by: ryan_618 ]

 

[curt swartz]

Re: Lighting load

Steve

210.19(A) requires the branch circuit to be rated at 125% of the continuous load.

As Ryan and iceman said the 150va/2ft (220.12(B)) is only required for service and feeder calculations. You could have 1000' of track on a single 20 amp circuit as long as the total fixture load on the track does not exceed 16 amps.

 

[russ]

Re: Lighting load

I think 220.12(B) may have caused some of the confusion. It pertains to Feeder and Service demand factors.
I agree with iceman and ryan. 210.19 and .20 require you to keep the load to 16 amps.

Russ

 

[russ]

Re: Lighting load

didn't see you coming curt.

 

[hillbilly]

Re: Lighting load

I'm going to add more track where the owner wants it. He's planning on 65 watt fixtures and I'll inform him that he can have up to 30 on each individual 20A (switched) circuit. If it's not enough, I'll have to install more homeruns (which will be a real PITA).