| HID xenon bulbs are quite a recent development in | | | | however because of the high voltages associated |
| automotive lighting technology. The HID stands for High | | | | with HID systems always make sure the electrical |
| Intensity Discharge, which refers to the unique way in | | | | power is off, and if you are at all unsure arrange to |
| which the bulbs produce their light. Unlike ordinary | | | | have the work carried out by a qualified mechanic or |
| halogen headlight bulbs, HID xenon bulbs do not contain | | | | auto technician. |
| a conventional metal filament, so in order to ignite the | | | | When buying replacement HID bulbs you may be |
| xenon gas and metal halide within the glass bulb a | | | | surprised at their high price, especially when compared |
| very high voltage spark is needed which is delivered | | | | to standard halogen headlight bulbs, however they do |
| by two electrodes. | | | | not have to be replaced in pairs and because of their |
| The high voltage that is used to generate the spark is | | | | exceptional service life they do still offer great value |
| around 20,000 volts, which is considerably higher than a | | | | for money. There is also now a growing range of |
| car's normal 12 volt supply and so a metal box, called a | | | | upgrade HID xenon bulbs that allow you to personalise |
| ballast unit, is fitted to help boost the voltage. Once the | | | | the night time appearance of your car. Whilst the |
| spark has been generated and the bulb is illuminated | | | | standard HID bulbs produce a white light with a yellow |
| the voltage drops down to a steady 85 volts. | | | | tint, upgrade xenon bulbs are available in blue, purple or |
| The xenon gas belongs to the group of elements | | | | pure white tints. |
| known as the noble gases, and is held within a single | | | | Because they produce such a bright light many drivers |
| sealed glass tube above the base of the bulb. When | | | | wonder whether HID Xenon bulbs are actually road |
| ignited the xenon helps to produce a light that is 300% | | | | legal. Well the simple answer is that they are |
| brighter than halogen, and because the light is also | | | | completely road legal if they are part of a |
| much whiter it more closely resembles natural daylight. | | | | manufacturer's factory fitted HID lighting system. It is |
| The bulbs used in HID xenon headlights typically last | | | | possible to buy aftermarket kits that upgrade standard |
| around 3000 to 4000 hours and when they do finally | | | | halogen headlights to HID xenon bulbs, however at |
| fail they normally give a warning by flickering | | | | present the law does state that these type of HID |
| intermittently before eventually failing to light up at all. It | | | | conversion kits are not legal. |
| is possible to change these xenon bulbs yourself, | | | | |