Home Depot carries replacement lamp Philips 70-Watt BD17 Ceramalux™ High Pressure Sodium HID Light Bulb, Model # 140913. Closest to a part number, the lamp is known by Philips as C70S62/M, their Ordering Code, where C = Ceramalux, M = medium base and 70 is wattage. No matter what brand, S62 refers to the size and shape of the glass bulb, known in the industry as the envelope. A similar naming convention is used for other brands, but they would have a different prefix because Ceramalux is a Philips registered trademark (™). This replacement lamp should not be confused with Philips 70-Watt ED23.5, which has a mogul base, a commercial size that is larger than a standard, "medium," Edison base; in other words, a mogul base is too large to screw into this fixture socket. Different numbers may appear on an original equipment lamp because they are usually generic bulbs made in China, which typically are rated to last an average 10,000 hours. This Philips replacement lamp is made in USA and rated to last 24,000 hours [industry-wide American standard] or about 6.58 years, based on a year-around average usage of 10 hours darkness per night; some American lamps may last 10 years or more, as in reviews. To get the exact average number of hours darkness in your latitude, check the times for sunset the night before the first day of spring or fall and sunrise the morning after, calculating the number of hours between [difference], as the earth will have traversed half way between the days of the shortest and longest numbers of hours of daylight. Some descriptions may estimate yearly operating cost, using a certain cost per Kwh [kilowatt-hour] and based on usage of 3 hours per day, which is not realistic dusk-to-dawn use, nor is estimated lamp life in double-digit years, based on such fictitious usage. Monitor an HPS bulb as it approaches life expectancy when it will go off when it should be on, then cycle back on. As it ages at end of life, it will cycle off and back on more and more frequently until it finally cycles off as soon as it reaches full brilliance, the back on after it cools and re-ignites [an HPS bulb is a machine with moving parts]. Do not wait to replace because the unnecessary cycling shortens the life of the ballast. This cycling is variously referred to in reviews as blinking, flickering, etc. If this behavior occurs when new, the fixture's photocell is receiving too much light upon full brilliance and thinks it is dawn; too much light may be reflected from a light-colored soffit, fascia, gutter, etc. requiring a blinder on the photocell if nothing else is changed.
Date published: 2016-09-22