Digital ballasts are not switchable theres no need for a switch they are digital and can fire MV/MH/HPS and LPS lights without a switch. Also make sure your ballast is not grounded to your Tv cable. .
Radio Frequency Interference ("RFI") and Electro- Magnetic Interference ("EMI")
Since electronic ballasts are operating at considerably higher frequencies than standard ballasts, they may create interference problems within communications systems. Many electronic ballast manufacturers have issued disclaimers on their product if used in conjunction with power line carriers. The FCC has established an acceptable level for class A applications, but ballasts operating in the high range of this standard can still cause problems in today's workplaces, particularly if the cabling is unshielded...and this is a fairly common situation.
There are some ballasts available, however, that operate in the low range of this standard and which will cause no problems, even in sensitive situations.
Typically, one is focused on what is going to ha ppen to light output and current draw when converting to T-8 lamps in conjunction with an electronic ballast. (There are a couple of series of T-8 lamps...both are rated 32 watts but one exhibits both higher lumen output and higher color resolution.) Input wattages of 58-62 are pretty standard for an electronic ballast and two 32 watt T-8 lamps. Typical decent ballast factors (the percentage of a lamp's rated lumens which will be driven out by the ballast) range from 91-96.
If 3 and 4 lamp ballasts are considered, input wattages per lamp will be lowered...but so will the ballast factor! Our experience with 3 and particularly 4-lamp ballasts (regard-less of manufacturer) has been that they are statistically less reliable than 2-lamp ballasts. Increased efficiency often comes at a cost of lower light levels and higher replacement costs.
It is a well-known fact that by utilizing a softer-starting mechanism, the expected life of fluorescent lamps is significantly extended. Rapid-start mechanisms preheat the lamp's electrodes before the required voltage for striking the arc is applied. Instant-starting a lamp, on the other hand, applies the jolt of required voltage without a warm-up period. As one would expect, instant-starting is much harder on the electrode, erodes it prematurely and results in predictably fewer lamp starts before failure. Although lamp replacement cost is not a particularly large percentage of the overall cost of lighting a facility (the dominant portion of cost, by far, is found in the light bill), it is the cost of most concern to a maintenance department since they don't pay the utility bills.
Patterns of usage determine whether or not a facility needs to be concerned with a ballast's starting mechanism. If a facility has long, uninterrupted burn times, then instant starts will have only a minimum effect on lamp life , and one can predict "reasonable" replacement cost values. Many facilities, however, have adopted the policy of turning out lights in unoccupied spaces, even if they are to be unoccupied for short periods. Management edicts and occupancy sensors ensure that this energy savings occurs. This policy results in lots of starts for the lamps. Because a typical instant-start ballast may give only 10,000 starts before the lamp fails vs. say, 50,000 starts for a soft-start ballast, the trade-off is clearly defined.
"Crest Factor"-- Lamp current Crest Factor directly impacts lamp life. It is defined as peak current divided by average current as delivered by the ballast to the lamp(s). Most lamp manufacturers recommend or require a crest factor of < 1.7 and note that 1.414 is a perfect current sine wave...simply as good as it gets for maximal lamp life. So, while "crest factor" deals with the impact of current or amperage on projected lamp life, the impact of voltage is primarily addressed through the starting mechanism3. Parallel vs. Series-Wired Circuits.
Historically, series-wired circuits have been rapid-started and parallel circuits have been instant-started.
The advantage of parallel-wired lamps is that, should one burn out, the other lamps in the fixture continue to function at full strength and the fixture still has sufficient light coming out of it to illuminate the workspace. If the lamps are on a series- circuit, however, and one lamp fails, they both shut down and the fixture ceases its function.
Many of today's office spaces draw their primary light from a single overhead fixture. If this fixture is a series-wired 2- lamper, the implications are obvious. On the other hand, when the "goodness" of parallel circuitry is coupled with instant-starting (as it usually is), the facility operator should be aware of the trade-off...i.e., assurances of continuous light and uninte rrupted productivity may be at the expense of lamp replacement costs.
The facility operator who is concerned with both reason-able lamp life and uninterrupted lighting will be looking for an electronic ballast that is both soft-starting and parallel wired.
Of course, if a facility has a "rapid-response" to lamp failure, potential problems of either system are neutralized. In the case of series-wired, the light is restored promptly and in the case of parallel-wired, the ballast's operating characteristics are maintained. (When one lamp burns out on a parallel circuit, the ballast's load characteristics change and so do some important criteria...namely Harmonic Distortion ("HD") increases and expected ballast life is reduced...both are good reasons to quickly replace the failed lamp).
This particular operating characteristic has been brought pretty much under control as far as the ballasts themselves being generators of dangerously high levels of harmonic distortion. The fact is, a well-structured lighting retrofit will drastically lower the volume of current drawn down by the lighting system. Since the percentage of HD generated by today's crop of electronic ballasts is lower than the standard magnetic ballasts they replace, the overall effect is, almost without exception, a lowered volume of HD in the electrical distribution system as a result of the retrofit.
Still, with the proliferation of non-linear loads, harmonic distortion of any magnitude may create an operating problem. Lowered volume of HD is obviously better than higher, particularly if it can be achieved without sacrifice. We are convinced, however, that it is almost always better to completely eliminate HD through filtering so that proper functioning by all loads requiring a relatively clean sine wave is assured.
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