Single Ended Halogen

Single-ended halogen bulbs have all electrical connections on one end of the bulb, distinguishing them from double-ended halogen bulbs where connections are at both ends. This single-ended design allows for more compact fixtures and easier bulb replacement – you simply plug the bulb into a socket rather than aligning and securing contacts at both ends. The category includes everything from tiny capsules for specialty applications to larger bulbs for theatrical and architectural lighting.

Base configurations in single-ended halogens are remarkably diverse, reflecting the wide range of applications these bulbs serve. You'll find familiar bases like medium screw (E26) and candelabra (E11), specialized bayonet bases (BA15s, BA15d, BA9s) common in automotive and indicator applications, two-pin bases (G4, GY6.35, GU5.3) for compact capsules, and various proprietary bases designed for specific fixture types or manufacturer requirements. The base type determines how the bulb mounts and connects electrically, so exact matching is essential for replacements.

Envelope shapes vary based on application requirements. Compact capsules provide high output in minimal space for under-cabinet lighting, decorative fixtures, and desk lamps. MR (multifaceted reflector) bulbs integrate reflectors for controlled beam patterns in track and recessed lighting. T-shaped tubular bulbs work in linear fixtures and specialty applications. Double-envelope bulbs have an outer protective shell around the inner halogen capsule, allowing safer operation in exposed fixtures and reducing UV output.

Voltage specifications span a wide range in single-ended halogens. Low-voltage versions (6V, 12V, 24V) are common in landscape lighting, automotive applications, and specialized equipment – these require transformers to step down from line voltage. Line-voltage versions (120V, 130V) plug directly into standard electrical circuits. Some specialty bulbs operate on unusual voltages dictated by specific equipment requirements. Installing the wrong voltage bulb is a common error that results in immediate failure (overvoltage) or insufficient light output (undervoltage).

Operating temperatures in single-ended halogens can be extreme, particularly in compact capsule designs where high output is concentrated in a small envelope. Surface temperatures can easily reach 500-600°F during operation, hot enough to cause serious burns or ignite nearby materials. Many single-ended halogens must be used in enclosed fixtures that shield the bulb from contact. Some require specific mounting orientations (base-up or base-down) to ensure proper heat dissipation and achieve rated life. These requirements are typically marked on the bulb or packaging.

One practical consideration specific to halogen bulbs: avoid touching the glass envelope with bare hands during installation. Oils from skin can create hot spots on the glass that lead to premature failure. If you do touch the glass, clean it with alcohol before installing. This matters more with single-ended halogens than with double-ended types because the more compact single-ended designs often run at higher envelope temperatures where skin oils are more likely to cause problems.

LED replacements are available for many common single-ended halogen types, particularly popular bases like G4, GY6.35, and E11. The energy and cooling advantages can be substantial – a 2W LED can replace a 20W halogen capsule while running cool enough to touch. However, compatibility with existing dimmers and transformers varies, and the light distribution pattern may differ from the original halogen. For applications where dimming behavior and exact light quality are critical, halogen may remain the better choice despite LED's efficiency advantages.

Common Base Types: Medium screw (E26), candelabra (E11), mini-can (E11), bayonet (BA15s, BA15d, BA9s), 2-pin (G4, GY6.35, GU5.3, various), specialized proprietary bases

Envelope Styles: Compact capsules, MR reflector bulbs, tubular (T-shape), double envelope (protective outer jacket), various specialty shapes

Applications: Under-cabinet lighting, decorative fixtures, desk and task lamps, track and recessed lighting, stage and theatrical lighting, architectural and display lighting, automotive and marine, specialty equipment