R50 and R63 reflector bulbs: how they differ from spotlights

How R50, R63 and R80 reflector bulbs are built, their beam and caps, how they differ from GU10 and MR16 spotlights, and what to consider when choosing.

In some ceiling fittings, particularly recessed "can" downlights installed in the early 2000s, you will find a bulb with a domed back and a flat front instead of a normal spotlight. Its cap is not a pin base like GU10 but an ordinary E14 or E27 screw. This is a reflector bulb, and names like R50 and R63 are often confused with spotlights.

What the "R" and the number mean

The "R" stands for reflector. For R lamps, the figure shows roughly how wide the front face is, in millimetres:

• R39: small, E14 cap, for narrow fittings and display cases;
• R50: usually E14, the most common size in recessed downlights;
• R63: usually E27, larger downlights and ceiling fittings;
• R80: E27, larger fittings and wider areas.

The cap tends to follow the size, but this rule is not absolute. When choosing, check both the diameter and the cap separately.

How a reflector bulb works

In the incandescent era, the inside of the domed back of an R bulb's glass was mirror-coated. Light from the filament bounced off this coating and was directed forward to the flat front face. Because the front was frosted, the light spread in a soft, wide cone.

LED reflector bulbs keep the same shape, but the principle changes. The diodes already emit light in a given direction, while the body houses the heat sink and driver. The front carries a diffuser or lens. The result is a bulb with the same shape and cap as the old one, still sending light forward.

How they differ from spotlights

In everyday speech any directional bulb gets called a "spot", but R bulbs differ from GU10 and MR16 spotlights in several ways:

• Cap. R bulbs use E14 and E27 screw caps; GU10 has bayonet pins, and MR16 has thin pins.
• Beam. Classic R bulbs give a wide, soft beam. Spotlights come in many narrow-beam versions better suited to accent lighting.
• Size and shape. R63 and R80 bulbs are much larger and longer than a GU10, so they do not fit the same fittings.
• Voltage. R bulbs run directly on mains, whereas MR16 often uses a 12 V transformer.

In other words, even if an R50 and a GU10 have the same diameter, they are not interchangeable. The holder in the fitting decides.

Alongside R bulbs you will also see PAR bulbs, such as PAR20, PAR30 or PAR38. They are reflector bulbs too, but designed to gather light into a narrower, more intense beam. In the incandescent era, a PAR bulb had thick glass with a lensed front and was chosen for outdoor use, display windows and throwing light over a distance. PAR sizes are counted in eighths of an inch rather than millimetres. So R and PAR bulbs cannot be compared by the number alone; check the size in millimetres on the box.

Where they are used and what to check

R bulbs mainly turn up in:

• large recessed downlights in suspended ceilings, especially older installations;
• adjustable E14 and E27 spotlights mounted on walls or shelves;
• shop displays and shelf lighting;
• shallow enclosed shades where light is meant to go downwards.

When replacing an old reflector bulb with LED, these points matter:

• Length. The LED version may be slightly longer because of the heat sink. Check the depth of the downlight.
• Beam angle. Compare the angle on the box with the old bulb's light; a very narrow beam will concentrate light into a pool.
• Colour temperature. If a room has several R bulbs, they should all match.
• Heat. In a deep, enclosed recessed fitting, leave an air gap for the LED bulb's heat sink.

Replace the bulb or the fitting?

If the fitting is sound and the holder is in good condition, swapping the R bulb for a suitable LED version is the simplest route. But if the fitting is old, the holder has scorched, or the ceiling is due for renovation, replacing large R downlights with GU10 or integrated LED fittings can be more flexible: the choice of lamps widens and the beam is easier to fine-tune.

The Zəfər İşığı catalogue offers GU10 spotlights as well as an adjustable 3D spot. When updating ceiling lighting, you can search the catalogue by cap to find a lamp that matches your fitting.