50A Max Lighting Rule
- Thread starter alcornjr
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I see no exceptions listed after 240.5(B)(1), it that's what you're referring to. But that's for fixture wires, not branch circuits.
Volta
Senior Member
- Location
- Columbus, Ohio
Also no exceptions to 210.23(D).
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
And the fixture wires get connected to the branch circuit conductors.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
And those rules do not go higher than 50 amps overcurrent protection.
The application of my post involves exterior fixtures where a solution to the problem they are having on site for some circuits for those fixtures is to upsize the breaker. Each fixture ramps WAY up on start-up then goes to working amperage. Breakers are triping on this start-up. Two circuits utilize 50 amp breakers where at start-up amps ramp up to 80 amps for circuit (for 3 seconds or so) then operate at 38 amps thereafter. I'd like to increase these breakers if possible and be code compliant.
Volta
Senior Member
- Location
- Columbus, Ohio
How many fixtures are on the circuit(s)?
Volta
Senior Member
- Location
- Columbus, Ohio
210.23(D) is not voltage-dependant. What is the applied voltage, are the fixtures multi-tap, and is there a higher premises voltage system present?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
You need a breaker with a different trip curve, if that is not done easily you could install fuses with trip curve that will fit the need. Or you may have other problems with the breaker. Most 50 amp breakers will likely hold an 80 amp current for 3 seconds or even longer see that kind of thing all the time trying to start motors.
The worst case scenario is there are 36 lights on one circuit. Calculations, per fixture cutsheet, and metering both show 40A at normal operation for this circuit. 40A X 1.25 = 50A ckt bkr. However, metering (24hrs/day for a week) shows that this circuit during the first 2 seconds ramps up to about 75 amps then operates at the 40 amps aforementioned. 120V circuit. The only solution I see to not exceed this 50A bkr is to add another circuit to split up this circuit. The less cost effective solution may be able to change out the ballast to 240V. The most cost effective solution would simply put an 80 A breaker in, but I think that is not code compliant since, I think, you cannot exceed 50A breaker for a lighting circuit.
- Location
- Illinois
- Occupation
- retired electrician
What breaker are you using? What does the time trip curve show for this breaker? I just looked a the curve for a 50 QO breaker and it shows a trip time of about 12.5 seconds with a current of 100 amps. It looks like it would be about 18 seconds for an 80 amp current.
Volta
Senior Member
- Location
- Columbus, Ohio
That makes me wonder about the line and load connections to the breaker.
dbuckley
Senior Member
- Location
- Canterbury, New Zealand
If changing the breaker curve doesn't do it for you, ff the 36 fixtures are in a line or otherwise sub-dividable, you could pop a couple of "delay on" timers in the chain, so the inrush is spread over two or three lumps, rather than one big lump.
I am also looking into the timer relays. Timer relays would work...but would have to be put in line at best locations. The circuit can never exceed 50A...so TR's can be put after a certain amount of lights...they ramp DOWN, then the next set of lights come on. HOWEVER...with the next set of lights that ramp up I have to account for the past light's amperage that have already ramped down.
Thank You all for your help.
Thank You all for your help.
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