Allmand Light Tower Bulb Replacement: Metal Halide and LED Conversion
When to Replace a Metal Halide Lamp
Metal halide bulbs on Allmand light towers (1000W or 1250W typical) have a rated life of 5000-10000 hours, but rental yard practice is to replace any bulb that takes more than 60-90 seconds to strike, runs noticeably dimmer than its neighbors, or has visible discoloration on the inner arc tube. A bulb at end-of-life will usually throw an Allmand fault code 9 (Lamp No-Strike) before it fully fails. Replace before it fails -- a bulb that goes dark in the middle of a night shift creates a customer callback at 2 AM that nobody wants.
Replacement Procedure (90 seconds per bulb)
Lower the tower fully and let the bulbs cool for at least 10 minutes -- metal halide bulbs run hot enough to burn through gloves. Open the lamp head with the latches on the side. Twist the old bulb counter-clockwise to release it from the medium-base socket. Don't touch the new bulb's glass with bare hands -- skin oils create hot spots that shorten life. Twist the new bulb in clockwise until snug. Close the head and confirm the gasket seats. Run the lamp through a strike cycle from cold to verify it lights.
Bulb Specs and Sources
Allmand Night-Lite Pro II and Maxi-Lite II use 1000W M47 metal halide lamps with a medium base (E39 mogul on some older units). Common OEM part numbers: GE Lucalox MVR1000/U/PA, Philips MS1000/HOR/BU. Aftermarket equivalents from Westinghouse and Sylvania run $20-$45 each. Buy in case quantities of 6-12 if you're maintaining a rental fleet -- you'll go through them. Pricier ceramic metal halide bulbs (CMH) run cleaner and last longer but draw the same wattage.
Ballast Troubleshooting (When New Bulb Doesn't Strike)
If a fresh bulb won't strike, the ballast is the next suspect. Allmand uses a magnetic ballast inside the lamp head with an igniter and capacitor. Open the head and visually check for swollen or leaking capacitors -- they fail more than anything else. Test ballast output voltage with a meter rated for 600V AC: open-circuit secondary should read 250-350V depending on the ballast tap. If the bulb tries to strike but doesn't sustain, the capacitor is most likely. If it doesn't try at all, the igniter is the next part. Whole-ballast replacement (capacitor, ballast, igniter as a kit) runs $80-$150 and is the easy fix when chasing intermittents.
Wiring and Socket Issues
Less commonly, a no-strike traces to corroded socket contacts (usually after water ingress) or a chafed wire feeding the head. Pull the bulb, inspect the socket center contact and threaded shell, and clean any green or white corrosion with a fine wire brush. Check the wire from the head down the mast for chafing where it runs through the cable carrier. Re-routing or wrapping a chafed cable is cheaper than chasing intermittent codes for a year.
LED Retrofit: Worth Considering
Metal halide is increasingly replaced by LED in jobsite light towers. LED retrofit kits for Allmand Night-Lite II convert each 1000W head to a 250-300W LED panel with similar light output, longer life (50,000+ hours), and instant strike. Retrofits run $400-$600 per lamp head plus labor. Payback is usually 18-24 months on bulb cost alone, faster if you account for fuel saved by the lower load on the genset. Newer Allmand models (Night-Lite Pro V and current production) ship with LEDs from the factory.
Maintenance Checklist for Rental Yard
On every Allmand tower coming back to the yard: (1) Inspect each lamp head for water ingress through the gasket. (2) Verify all 4 lamps strike from cold within 90 seconds. (3) Check the mast cable carrier for wear or kinks. (4) Lower mast fully and confirm the down-limit switch registers (Allmand fault 11). (5) Test the up-limit switch by extending fully (Allmand fault 10). (6) Test outrigger limit switches by deploying and stowing each one (Allmand fault 13). 5 minutes of yard prep avoids 50 percent of the customer callbacks on jobsite lighting.