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Once current starts flowing through the lamps, the lamps illuminate at close to their full brightness. After a successful start, the instant-start ballast will immediately regulate the voltage and current down to the normal operating levels.
Traditional instant start lamps could be identified by having either a single pin on each end of the lamp, or by having recessed contacts. (Recessed contacts are used in "High Output" lamps containing "HO" in the lamp model number.) However, with the advent of electronic ballasts, the newer T-8 (1.0" diameter) "F0" and "FB0" series lamps are bi-pin designs but are meant for use with special instant start ballasts.
Because of the higher voltages and current involved with these fixtures, older instant-start designs using magnetic ballasts employ special lamp sockets that are designed to disconnect the fixtures power source when a lamp is removed. Most electronic ballasts do not need this interlock, as the ballast is able to detect the absence of a lamp and shut down that portion of the ballast automatically. The electronic ballast designs commonly allow less than the maximum allowed number of lamps to be attached to the ballast, and the remaining lamps will operate correctly. Older magnetic ballast designs require that the stated number of lamps be connected and in working order or some or all of the lamps may not illuminate fully or at all.
High Output lamps, which are a high-current type of instant start lamps, are designed to start and operate in cold environments and were originally used in walk-in freezers. Today, they are commonly used in outdoor signs as well as grocery store freezers and other applications. In addition to their ability to work at colder temperatures, High Output lamps produce more light than normal fluorescent lamps of the same size.
High Output lamps have a plastic or similar material surrounding recessed contacts on each end of the lamp itself. This prevents High Output lamps from being used in the wrong types of fixtures, and may provide some protection from moisture making electrical contact with the lamp contacts.
A curious feature of many instant start lamps is that they also have filaments in each end of the lamp, but frequently both ends of the filament are wired together so the filament can never be heated. The filament simply acts as a cathode material that is a suitable source of electrons.
Notes:
Wiring color and how the wires are to be connected may vary by ballast
manufacturer, so always refer to the diagram on the ballast used and follow
its instructions.
In the above design, when a lamp is absent, the power supply to the fixture that passes through two of the lamp sockets (on left in drawing above) is disconnected, causing the entire fixture to shut down. The electrical contact on the lamp itself acts as a power supply control switch.
| Caution: If the fixture you have has two wires connected to the socket on both ends of every lamp (a total of four wires per lamp), it means that you probably really have a Rapid-Start or Pre-Heat fixture, not an Instant Start fixture. Please refer to Sections 4 or 5 for details on these other designs. |
Notes:
Wiring color and how the wires are to be connected may vary by ballast
manufacturer, so always refer to the diagram on the ballast used and follow
its instructions.
| Caution: If the fixture you have has two wires connected to the socket on both ends of every lamp (a total of four wires per lamp), it means that you probably really have a Rapid-Start or Pre-Heat fixture, not an Instant Start fixture. Please refer to Sections 4 or 5 for details on these other designs. |
The best F40T12 lamps currently produce 3,300 lumens while consuming 40 watts, while F032T8 lamps are available that produce 2,950 lumens but only consume 32 watts. Despite the lower amount of light produced by the F032T8 lamp, because the light is coming from a smaller space, the T-8 lamps also create an illusion that T-8 lamps are brighter than the equivalent T-12 lamp, even though the T-8 lamp is actually producing less light. Note also that if you were already using T-12 34 watt lamps, virtually all T-8 lamps will produce more light for 32 watts.
Note that 32 watt T8 lamps produce more lumens per watt than any T12 lamp of the same length, so the T8 lamps are superior when it comes to power consumption, but when replacing existing T12 with T8 lighting, the lower light output may cause areas to be under-lit.
I have also seen cases where fixtures with two F96T12 lamps that consume between 60 and 75 watts each were "modernized" to hold four F032T8 lamps (pairs of lamps mounted end-to-end) and a new electronic ballast. The reworked fixture now consumes about 128 watts, rather than the 120 to 150 watts consumed by the older design. With the right choice of lamps, the modernized fixture could produce more light with less electricity consumed, and has the reliability that three of the four lamps can fail or wear-out and the fixture will still be producing some light.
In some instant start electronic ballast designs, the ballast manufacturer allows the same ballast to be connected to one to four lamps. The unused wires are simply insulated and not connected to anything.
Section 7: Compact Fluorescent Fixtures (HTML) [NEXT]
Section 4: Traditional Pre-Heat Fluorescent Fixtures (HTML)
Section 5: Rapid-Start Fluorescent Fixtures (HTML)
Return to The Fluorescent Lighting Reference Index (HTML)
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