Part number MH175/U/M replaces 15556, 2020180010, 30721370199, 58041, 69549016903, 69549580411, 715060, M175U/MED, M175X/U/MED

Metal Halide (HID)

Ballast Compatibility:

• Magnetic (core & coil) ballasts rated M57, 175W metal halide
• Electronic ballasts rated for 175W metal halide
• Multi-tap ballasts (120V, 208V, 240V, 277V, 480V) with M57 designation
• Probe-start and pulse-start ballasts (verify lamp compatibility — this is a probe-start lamp)

Common Fixture Brands:
Lithonia, RAB Lighting, Hubbell, Cooper Lighting, Philips Stonco, American Electric Lighting, Acuity Brands, MaxLite, Howard Lighting, Venture Lighting, TCP, Plusrite, Satco, GE, Sylvania, PhilipsNote: Always verify the ballast ANSI code (M57) and wattage (175W) match the lamp specifications. Using an incompatible ballast will cause lamp failure or unsafe operation.

1. Turn off power – Switch off the circuit breaker or disconnect power to the lighting fixture. Verify power is off before proceeding.
2. Allow bulb to cool – If the existing bulb was recently operating, allow at least 15–20 minutes for it to cool. Metal halide bulbs operate at extremely high temperatures and can cause severe burns.
3. Access the fixture – Depending on your fixture type (high bay, wall pack, flood light, etc.), remove the lens, cover, or access panel to reach the bulb.
4. Remove the old bulb:For mogul base (E39): Grip the bulb firmly and turn counterclockwise to unscrew from the socket.For medium base (E26): Same process — turn counterclockwise.Handle carefully — old bulbs may be fragile.
5. Inspect the socket – Check the socket for corrosion, damage, or loose connections. Clean contacts if needed. Replace socket if damaged.
6. Handle the new bulb properly:IMPORTANT: Do not touch the glass envelope with bare hands. Oils from skin can create hot spots that shorten bulb life or cause premature failure.Use clean gloves, a cloth, or handle by the base only.If you accidentally touch the glass, clean it with isopropyl alcohol before installing.
7. Install the new bulb:Align the base with the socket.Turn clockwise to screw in securely.Ensure the bulb is fully seated but don't overtighten.
8. Verify correct bulb orientation – Some fixtures require specific bulb positions (base up, base down, horizontal). Check fixture labeling or documentation.
9. Reassemble the fixture – Replace the lens, cover, or access panel. Ensure all components are secure.
10. Restore power – Turn the circuit breaker back on.
11. Test the bulb:The bulb will take 2–5 minutes to warm up to full brightness — this is normal.Initial light may appear bluish or dim, then shift to bright white as it warms.Verify the bulb reaches full brightness and maintains stable operation.
12. Note restrike time – If power is interrupted while the bulb is hot, it will take 10–20 minutes to cool before it can restrike (restart). This is normal for metal halide technology.

Metal halide bulbs require a compatible ballast — always verify ballast compatibility before installing. This MH175/U/M lamp requires an M57 ballast rated for 175W metal halide. Using the wrong ballast (wrong wattage, wrong ANSI code, or a ballast designed for a different lamp type like high-pressure sodium) will cause the lamp to fail prematurely, operate incorrectly, or not start at all. If you're experiencing frequent lamp failures, the ballast may be failing — ballasts degrade over time and can damage lamps when they malfunction. Signs of a failing ballast include lamps cycling on and off, excessive warm-up times, lamps failing prematurely, or humming/buzzing from the fixture. When replacing bulbs in multi-lamp fixtures, consider replacing all lamps at once for uniform light output and color — mixing old and new lamps results in uneven lighting. For applications where restrike time is problematic (the lamp won't restart for 10–20 minutes after power loss), consider switching to pulse-start metal halide or LED retrofits, which offer faster restrike and better efficiency. Always dispose of old metal halide lamps properly — they contain small amounts of mercury and should be recycled according to local regulations.