"IMPORTANT NOTE" the lamp must not be operated directly from the socket, the use of a choke coil - ballast for mercury lamps is required. This particular lamp requires a 125W mercury ballast, which reduces and regulates the voltage and current in order to protect the lamp from overload. The reduction for 125W: 1.15-1.2A and 120-125V, with this current a 125W high-pressure mercury lamp operates, and neither is an external starter required nor allowed, because mercury lamps have a built-in starter. The use of an external starter may cause lamp failure, and definitely a capacitor is needed for power factor correction. For 125W mercury, a 10μf capacitor is needed, no more, and with a resistance of at least 250V! Unfortunately, ballasts have low efficiency, with the power factor ranging from 0.4-0.5, where the ideal value is 1.00, meaning 100% of the energy is utilized, with no thermal losses, but such a thing is impossible, especially when it comes to transformers, autotransformers, or ballasts, even electronic ballasts, which have an almost perfect PF (power factor), usually 0.95-0.96, and modern ones at 0.98-0.99, but with the capacitor for power factor correction, it improves to 0.85-0.9.

The lamp is excellent for its price, especially when it is an Osram of German manufacture. These break down after many years, usually lasting over 25-30 years; you install it and after 30 years it needs replacement. There are many mercury lamps on Greek streets that have been there for decades and still illuminate with a characteristic white light and sometimes slightly green, and usually, those with slightly greenish light are dim, but there are also some with a strong green-yellow light. However, this is not due to the lamp but to the fixture cover itself, which yellows over the years with the sun, and the white light becomes dim green-yellow. However, there are also some, though very rarely, that have a slightly greenish-white and very dim light; these are usually over 30 years old and shine with much less brightness. In these cases, the reduction is at least 40-50%. This is the major drawback; usually, after 20 years, they lose about 30-35%, which means if a lamp gives 10,000 lumens, it will lose 30-35%, i.e., 7,000 or 6,500 lumens, and as the lamp approaches the end of its life, it will lose even more brightness. Therefore, every 15 years, replacement is needed to maintain effectiveness. However, high-pressure mercury lamps have very low efficiency, with a maximum of only 70lm/watt. That’s why quartz metal halide lamps, or even better, ceramic metal halide lamps, where the chemical reaction producing light occurs inside an arc tube made of ceramic instead of quartz, allowing higher temperatures and thus higher efficiency, reaching 120lm/watt. But the top for road lighting... are high-pressure sodium lamps, which reach a maximum efficiency of 150lm/watt, but their light is intense golden-white and orange-white, but their effectiveness is excellent. They are the most efficient HID lamps and the second most efficient discharge lamp that exists, with much better light retention, where usually after 10-12 years, which is their typical lifespan, they lose only 17-20%, and in rare cases over 25-28% if the high-pressure sodium lamp is over 15 years of daily operation, which rarely lasts that long!