I am looking at a cut sheet of a 4x4 parabolic fixture with three 32Watt T-8 lamps. I don?t know if it is one or two ballast. The cut claims a total input watts of 86 for the fixture. I have seen this before on other cut sheets also. How can you have a total wattage less than the lamps and the ballast?
Electronic ballast & total fixture wattage
- Thread starter dirk
- Start date
- Status
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Electronic ballast & total fixture wattage
What is the VA listed on the ballast?
What is the VA listed on the ballast?
Re: Electronic ballast & total fixture wattage
I usually figure that if you have(3)32w lamps with a single ballast, the total watts per fixture will not exceed 100w. that is a rough estimate. Which brand is the fixture? If it is cooper/lithonia I would use the spec sheet. If it is a dual ballast look up in a Advance Ballast book to determine how much the an additional ballast pulls.
I usually figure that if you have(3)32w lamps with a single ballast, the total watts per fixture will not exceed 100w. that is a rough estimate. Which brand is the fixture? If it is cooper/lithonia I would use the spec sheet. If it is a dual ballast look up in a Advance Ballast book to determine how much the an additional ballast pulls.
Re: Electronic ballast & total fixture wattage
Dirk,
The rated wattage to linear lamps is the 60 Hz. rating. A lamp operated by a high frequency electronic ballast operates more efficient than when operating at 60 Hz. This is the primary purpose for change to electronic ballasts. A lamp operating at high frequency will produce the same light output with less energy.
Dirk,
The rated wattage to linear lamps is the 60 Hz. rating. A lamp operated by a high frequency electronic ballast operates more efficient than when operating at 60 Hz. This is the primary purpose for change to electronic ballasts. A lamp operating at high frequency will produce the same light output with less energy.
Re: Electronic ballast & total fixture wattage
A characteristic of high frequency electronic ballasts is that the system efficiency is higher. The lamps put out more lumens while being operated a lower level of power consumption. So it is possible that the system wattage is 86 or 88 watts for a 3 lamp normal light output T8 fixture.
It is important to also consider the ballast factor of the ballast being used. The ballast factor (BF) determines how hard the lamp is driven and therefore how much light output and power consumption there is. For example a standard light output ballast will have a BF= to about .88, while a low light output ballast system will have a BF= to about .78. There are also high light output ballasts with BF= to about 1.18. The system wattage for each is different also.
A characteristic of high frequency electronic ballasts is that the system efficiency is higher. The lamps put out more lumens while being operated a lower level of power consumption. So it is possible that the system wattage is 86 or 88 watts for a 3 lamp normal light output T8 fixture.
It is important to also consider the ballast factor of the ballast being used. The ballast factor (BF) determines how hard the lamp is driven and therefore how much light output and power consumption there is. For example a standard light output ballast will have a BF= to about .88, while a low light output ballast system will have a BF= to about .78. There are also high light output ballasts with BF= to about 1.18. The system wattage for each is different also.
- Status