GU10 replacement: voltage, size, beam angle

How to identify a GU10 base

Switch off power and let the lamp cool. A GU10 base has two short, sturdy pins ending in widened heads. The bulb enters the socket and rotates a short distance to lock. The nominal spacing is 10 mm from the center of one pin to the center of the other.

Do not identify it from the reflector face alone. GU10 and GU5.3 bases are both commonly attached to MR16-shaped lamps. GU5.3 has two thin straight pins and pushes straight in; GU10 uses widened locking pins and turns. A PAR16 lamp can also use GU10, so the shape code and base code remain separate.

If the lamp is recessed behind a trim or mounted in a range hood, photograph the base and full marking as it comes out. Do not twist an unknown straight-pin lamp or pull hard on a locked GU10. Follow the fixture's release method when a retaining ring or suction tool is involved.

GU10 does not guarantee voltage

GU10 is often associated with line-voltage spotlights in U.S. homes, and many current Feit Electric MR16 GU10 LEDs are marked 120 V. That is a common product pattern, not a rule encoded in the base. The official catalog also contains a GU10 model with another stated voltage, illustrating why the exact marking must control.

Match the replacement voltage to the old lamp and fixture documentation. Do not infer it from the words GU10, MR16, LED, track light, or range hood. A physically matching lamp can still be wrong for the supply, transformer, or control system.

Use actual input watts for the fixture's wattage limit. A lamp advertised as a 50-watt replacement may consume only a fraction of that power, but the fixture's lamp-type, enclosure, orientation, or model-specific restrictions remain in force.

MR16 describes shape and size, not the socket

MR16 is a multifaceted-reflector shape designation with a nominal diameter class of 16 eighths of an inch, or 2 inches. That description applies to the reflector envelope. It does not tell you whether the connection is GU10 or GU5.3, and it does not specify voltage or beam angle.

PAR16 is another compact reflector designation found with GU10 bases. Even when two lamps share a nominal front diameter and GU10 connection, their necks, housings, and maximum overall lengths can differ. Check the fixture opening, trim, socket depth, and clearance behind the face.

Official product records show the separation clearly: Feit lists an MR16 GU10 LED at 120 V with a 40-degree beam and also publishes other GU10 reflector models with different wattage, output, or dimensions. Read the full line of specifications rather than treating MR16 GU10 as one fixed lamp.

Beam angle changes where the light goes

Beam angle describes the spread of directional light. A narrower beam concentrates light on a smaller area, while a wider flood distributes it more broadly. GU10 does not determine beam angle, and two bulbs with the same base, lumens, and color temperature can produce noticeably different lighting on artwork, counters, floors, or walls.

Match the old beam angle when preserving an existing lighting effect. If the old value is unknown, consider the distance to the target and the size of the area that should be illuminated. A range hood generally needs useful coverage of the cooking surface, while an accent spotlight may intentionally use a tighter beam.

Lumens measure total light output, not beam width. Compare both specifications. Also check color temperature and color rendering if the lamp illuminates finishes, food, artwork, or merchandise where appearance matters.

Check dimming, heat, and location ratings

For a dimmed fixture, the exact GU10 lamp must be labeled dimmable and compatible with the installed control. Driver and dimmer combinations can differ in minimum level, start-up, flicker, ghosting, and audible noise. Use a manufacturer compatibility list when one is available.

Recessed cans, small track heads, and range hoods may retain heat. Use a lamp with explicit approval for the enclosure or operating condition stated by the fixture manufacturer. The Department of Energy warns that trapped heat can affect some LED lamps, so a lower actual wattage does not make every LED suitable for every covered fixture.

Moisture and temperature requirements are separate. A range hood may impose appliance-specific heat, grease, size, or shield requirements. An outdoor spotlight needs the appropriate dry, damp, or wet-location rating. GU10 alone answers none of those questions.

Seating the replacement in a GU10 socket

Start with the full old-lamp code and fixture label. Record the base, voltage, shape, maximum diameter, overall length, actual watts, lumens, beam angle, color temperature, dimming status, and any enclosure or location rating. Search the exact model where possible.

When installing, align the widened pins with the socket openings, push gently, and rotate only as directed. If it will not lock without force, stop and recheck the base and socket condition. Restore trim, shields, and retaining rings exactly as the fixture manufacturer specifies.

• Confirm widened GU10 pins and nominal 10 mm spacing.
• Match the printed voltage rather than assuming line voltage.
• Check MR16 or PAR16 diameter and exact overall length.
• Match lumens, beam angle, color temperature, and color rendering.
• Verify dimmer, enclosure, range-hood, and location requirements.