WE HAVE INSTALLED A NEW LIGHTING SYSTEM IN A HARDWARE STORE AND WE HAVE INCURRED A HEATING PROBLEM WITH THE WIRE AND CONDUIT KUST TO THE LIGHTS AND THRU THE CONTACTORS . WE HAVE PULLED FIVE CIRCUITS IN EACH CONDUIT 1" TO THE CONTACTORS WE THINK THE ISSUE IS HARMONICS BUT NEED A FIX THE CONDUIT RUNS ATRE APPROXIMATELY 100' THERE ARE # 10 WIRE IN THE PIPE FIVE HOTS AND FIVE NEUTRALS ONE GROUND WIRE SIX EIGHT FOOT LIGHTS ON A CIRCUIT EACK HAVE SIX LAMPS I NEED SOME SUGGESTIONS TO REMEDY THE SITUATION
HIGH OUTPUT T5 LIGHTING
- Thread starter IKINDER
- Start date
- Status
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: HIGH OUTPUT T5 LIGHTING
Please turn off the ALL CAPS feature. It makes the post more difficult to read. It is also considered impolite, as though you were SHOUTING at us.
Please turn off the ALL CAPS feature. It makes the post more difficult to read. It is also considered impolite, as though you were SHOUTING at us.
Re: HIGH OUTPUT T5 LIGHTING
I looked up the wattage for an 8'T5 HO lamp an
I think it is 80 watts. You have 5 ckts of 2 # 10cu for a total of 10 #10's. You have 6 lights each with 6 lamps for a total of 36 T5 lamps.
36 lamps x 80 watts ea = 2880 watts or 24 amps
if the voltage is 120 volts. Since you have
10 #10s in the conduit the derating factor is 50%. The rating of #10 at 90C is 40 amps.
40 amps x 0.50 = 20 amps. I hope I am wrong.
Questions:
Do you have electronic ballast?
Voltage?
Wattage of the T5 lamp?
I looked up the wattage for an 8'T5 HO lamp an
I think it is 80 watts. You have 5 ckts of 2 # 10cu for a total of 10 #10's. You have 6 lights each with 6 lamps for a total of 36 T5 lamps.
36 lamps x 80 watts ea = 2880 watts or 24 amps
if the voltage is 120 volts. Since you have
10 #10s in the conduit the derating factor is 50%. The rating of #10 at 90C is 40 amps.
40 amps x 0.50 = 20 amps. I hope I am wrong.
Questions:
Do you have electronic ballast?
Voltage?
Wattage of the T5 lamp?
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: HIGH OUTPUT T5 LIGHTING
If I understand correctly, each circuit has six fixtures, and each fixture has six lamps. Presuming a 60 watt lamp (is that a reasonable value?????), that adds up to 2,160 watts. On a 120 volt circuit, that equates to 18 amps. Presuming that the lights are on for more than 3 hours at a time, you need to allow an extra 25% to account for the total load. That brings you up to 22.5 amps.
A #10 THHN (is that your type of wire) has a 90C rating of 40 amps. Ten current-carrying conductors in a single conduit require derating that to 20 amps. So it sounds like you have an ampacity problem. You have too many conductors in a single conduit feeding too many lamps. If there is a significant amount of harmonics (very likely), the ampacity problem gets worse.
I think you need to look into adding more conduits.
If I understand correctly, each circuit has six fixtures, and each fixture has six lamps. Presuming a 60 watt lamp (is that a reasonable value?????), that adds up to 2,160 watts. On a 120 volt circuit, that equates to 18 amps. Presuming that the lights are on for more than 3 hours at a time, you need to allow an extra 25% to account for the total load. That brings you up to 22.5 amps.
A #10 THHN (is that your type of wire) has a 90C rating of 40 amps. Ten current-carrying conductors in a single conduit require derating that to 20 amps. So it sounds like you have an ampacity problem. You have too many conductors in a single conduit feeding too many lamps. If there is a significant amount of harmonics (very likely), the ampacity problem gets worse.
I think you need to look into adding more conduits.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: HIGH OUTPUT T5 LIGHTING
I see Bob and I are thinking along the same lines, though he beat me to the draw in posting our thoughts. I found a high efficiency 8 foot lamp on line, and that was my source for my 60 watt per lamp assumption.
I see Bob and I are thinking along the same lines, though he beat me to the draw in posting our thoughts. I found a high efficiency 8 foot lamp on line, and that was my source for my 60 watt per lamp assumption.
karl riley
Senior Member
Re: HIGH OUTPUT T5 LIGHTING
If you suspect harmonics why not measure? Clamp an ammeter around the neutral/s. Are they carrying more current than rated for? Are they the hot (temp) conductors?
No need to guess when you can measure.
Karl
If you suspect harmonics why not measure? Clamp an ammeter around the neutral/s. Are they carrying more current than rated for? Are they the hot (temp) conductors?
No need to guess when you can measure.
Karl
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