4' T-8 4 LAMP
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junkhound
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yes, assuming electronic ballast since you specified t-8.
In fact, electronic ballasts say to simply put a wire nut on unused blue wires, taking bulb out same thing.
In fact, electronic ballasts say to simply put a wire nut on unused blue wires, taking bulb out same thing.
Electric-Light
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just the cowboy
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check ballast
check ballast
The ballasts I use have two power in wires one for each set of lights, this way it can be setup for half lighting.
check ballast
The ballasts I use have two power in wires one for each set of lights, this way it can be setup for half lighting.
Electric-Light
Senior Member
Many T5HO four lamp ballasts are like this. It improves reliability. They're essentially setup like two independent ballasts in one case. A failure of any one lamp will take out one lamp. A failure of any one ballast section takes out a pair of lamp. That way, there's a less of a chance of entire fixture blacking out which can trigger an immediate spot replacement due to the dark spot created. The ballast you speak of is also the type that often supports 1,2,3, or 4 lamp use.
I am not certain if luminaires employing permanent non user replaceable solid state semiconductor activated fluorescent lamps features this type of redundancy in its electronic ballast.
junkhound
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Interesting, have not seen that type electronic ballast - do you have an example mfg. part number handy to share?
Electric-Light
Senior Member
I am not going to dig it around. Non-primary configuration not listed on the label itself requires research on your part as electronic ballasts tend to be quite universal and sometimes supports beyond the configurations printed on the label. These are something you'd have to refer to detailed specifications pdf. It can change from revision to revision.
You'll find that many F32T8 ballasts support F40T8, but conditional to N-1 operation. I.e. you need a 3 lamp F32T8 ballast to operate two F40T8. If you operate three F40T8, you risk frying the ballast.
If you operate 2 F32T8 on 4 F32T8 ballast, you can count on one of them eventually failing and single lamping which can significantly over drive the lamp. It could also make the UL CC feature ineffective which is supposed to quench the arc by detecting loose socket.
Operating in any configuration that is not vetted for in spec sheet will void the warranty.
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N is the fully loaded number of bulbs for the ballast.
N-1 is leaving out one bulb, like 3 out of 4.
N-2 would be 1 out of 3 or 2 out of 4.
junkhound
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- Renton, WA
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- EE, power electronics specialty
I am not going to dig it around. Non-primary configuration not listed on the label itself requires research on your part as electronic ballasts..
No example part number means the original post was just BS? I have dis-assembled about 15 different electronic ballasts*, mostly the universal voltage type, and reverse engineered the circuit as part of some proprietary harmonic studies.
Every ballast I have tested and drawn out the internal schematic for will operate with any of the blue wires not connected. Overall efficiency of operating a 4 lamp ballast with only one lamp is however often less than with 3 or 4 lamps, but the overall power is almost proportionally less so there is less heat. The efficiency only drops due to some constant low loads that power a few mA of control circuitry.
* part numbers can be made available on request, but will require you sign a proprietary information agreement and have a corporate business arrangement with company ... or, you can consider the above all BS also <G>
No example part number means the original post was just BS? I have dis-assembled about 15 different electronic ballasts*, mostly the universal voltage type, and reverse engineered the circuit as part of some proprietary harmonic studies.
Every ballast I have tested and drawn out the internal schematic for will operate with any of the blue wires not connected. Overall efficiency of operating a 4 lamp ballast with only one lamp is however often less than with 3 or 4 lamps, but the overall power is almost proportionally less so there is less heat. The efficiency only drops due to some constant low loads that power a few mA of control circuitry.
* part numbers can be made available on request, but will require you sign a proprietary information agreement and have a corporate business arrangement with company ... or, you can consider the above all BS also <G>
Electric-Light
Senior Member
So, just select whatever ballast and download and inspect the datasheets yourself. :roll: They can't fit every possible permitted combination on the label, so you have to refer to the datasheet.
As you begin to remove lamps, the remaining lamps get brighter. This improves lumen maintenance, so you have say 85% light instead of 75% when one lamp on 4 lamp setup fails. It's not really expected that you'll run until all four lamp fails. If you start with two lamps, there's a good chance that you over-drive the lamps which can cause other problems like very fast lamp failures.
You must have only taken apart the instant start variety then. Some are series, some are series parallel. Earlier ballasts were less tolerant of abuse. Some will fail instantly if the heater wires are shorted of if any leads short to ground. Long time ago, Motorola made ballasts. They were especially fragile. Some even fail from hot-relamping. Some don't tolerate sitting 24/7 at starting voltage.
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