The lighting industry classes the incandescent light bulbs used in train accessories and train layout lighting as "miniature." Light bulbs are further defined by shape, size, and base style. Complete electrical specifications for light bulbs used in train accessories are given in a following table. The table is also click-referenced from the train accessory web page and the trackside accessory section.

Light bulb selection guides can help with choosing a light bulb for structure lighting or as substitute in an accessory.

The lighting industry designates globe shape with a letter. Most train accessory light bulbs have a "G" shape (round). A few are described as "pear" shaped. Globe size is designated with a number, which may be a fraction, or by a dimension. Typical train accessory light bulb sizes are:

• 3 1/2 -- 7/16" Diameter
• 4 1/2 -- 9/16" Diameter

The shape-letter and size are combined, e.g. G3 1/2, G4 1/2, to completely designate a light bulb's shape and size.

The "base" of a light bulb serves to mount the bulb and supply electrical power. Train accessory light bulb bases commonly used are: 2-PIN, MINI-SCREW (E10), and MINI-BAYONET (BA9S).

The 2-Pin base consists of two stiff rods, with 7/32" spacing, that protrude from the globe. It is plugged into a socket that holds the bulb and supplies electrical power. The socket is usually built into a plastic accessory.

The Mini-Screw base is a 3/8" diameter metal tube shaped with three rounded threads. The metal tube and a lead cone on the end of the base supply electrical power.

The bulb is installed in a matching holder by turning it clockwise until securely seated. It is removed by turning counter-clockwise.

The Mini-Bayonet base is a 3/8" diameter metal tube with two projections on opposite sides near the tube-end. The metal tube and a lead cone on the end of the base supply electrical power.

The bulb is installed in a matching holder by aligning the projections in two corresponding slots in the holder and pushing. A clockwise (usually) turn will secure the bulb. The bulb is removed by pressing in a little, turning counter-clockwise, and pulling out. Bayonet bulb holders may be a separate mechanism or may be a part of an accessory.

A light bulb is specified to operate at a voltage and the amperage that it will draw at that voltage. Watts, simply the product of "volts" and "amperes," is a useful value for judging relative light intensity and the heat generated by a light bulb. Higher "watts" means a brighter light, but also a hotter light bulb. The operating life of a light bulb is reduced when it is powered with higher voltages.

Train accessory vendors often specify a range for operating voltage. For example, an accessory with a 14 volt light bulb may be specified for operation at 12 - 16 volts. At 12 volts, the bulb will be less bright, generate less heat, and last longer. At 16 volts, the bulb will be brighter, generate more heat, and not last as long.

The lighting industry completely specifies a light bulb's shape, size, base, and electrical characteristics with a number, usually printed on the bulb's base. Light bulb manufacturer's typically incorporate this number in their own part numbers. A letter suffix may also be used to indicate a bulb's finish or color. Train accessory vendors use this number to designate an appropriate light bulb for an accessory.

The lighting industry number is used in following light bulb tables.

The following table lists light bulbs found in the Train Accessories Light Bulbs table. Additional bulbs are included for substitutions or for lighting in structures.

The list is ordered by industry number. Each entry shows globe shape/size, base style, voltage, amperes, and watts. Colors and variations available are shown. A picture of the light bulb is included.

BULB NUMBER	GLOBE SHAPE/SIZE BASE STYLE VOLTAGE AMPERES COLORS/VARIATION WATTS	BULB IMAGE
12	G3 1/2 2-Pin 6.3 VOLTS .15 AMPERES Red/Orange .95 WATTS
19	G3 1/2 2-Pin 14 VOLTS .1 AMPERES Clear 1.4 WATTS
50	G3 1/2 Mini-Screw 7.5 VOLTS .22 AMPERES Clear 1.65 WATTS
51	G3 1/2 Mini-Bayonet 7.5 VOLTS .22 AMPERES Clear 1.65 WATTS
53	G3 1/2 Mini-Bayonet 14.4 VOLTS .12 AMPERES Clear/Red/Green 1.73 WATTS
57	G4 1/2 Mini-Bayonet 14 VOLTS .24 AMPERES Clear 3.36 WATTS
257	G4 1/2 Mini-Bayonet 14 VOLTS .27 AMPERES Clear 3.78 WATTS
258	G4 1/2 Mini-Screw 14 VOLTS .27 AMPERES Clear 3.78 WATTS
293	G4 1/2 Mini-Bayonet 14 VOLTS .33 AMPERES Clear 4.62 WATTS
363	G3 1/2 Mini-Bayonet 14 VOLTS .2 AMPERES Clear/Red/Green 2.8 WATTS
428	G4 1/2 Mini-Screw 12.5 VOLTS .25 AMPERES Clear 3.125 WATTS
430	G4 1/2 Mini-Screw 18 VOLTS .25 AMPERES Clear/Red/Green 4.5 WATTS
431	G4 1/2 Mini-Bayonet 14 VOLTS .25 AMPERES Clear/Red 3.5 WATTS
432	G4 1/2 Mini-Screw 18 VOLTS .25 AMPERES Clear/Red/Green 4.5 WATTS
433	G4 1/2 Mini-Bayonet 18 VOLTS .25 AMPERES Clear 4.5 WATTS
461	G4 1/2 Mini-Screw 14 VOLTS .33 AMPERES Clear Dimpled 4.62 WATTS
526	21/32" Mini-Screw 18 VOLTS .25 AMPERES White 4.5 WATTS
1442	23/32" Pear Mini-Screw 18 VOLTS .25 AMPERES White/Frosted/Pearl 4.5 WATTS
1445	G3 1/2 Mini-Bayonet 18 VOLTS .13 AMPERES Clear 2.34 WATTS
1446	G3 1/2 Mini-Screw 12 VOLTS .2 AMPERES Clear 2.4 WATTS
1447	G3 1/2 Mini-Screw 18 VOLTS .15 AMPERES Clear 2.7 WATTS
1448	G3 1/2 Mini-Screw 24 VOLTS .035 AMPERES Clear .84 WATTS
1449	G3 1/2 Mini-Screw 14 VOLTS .2 AMPERES Clear/Red/Green 2.8 WATTS
1450	G3 1/2 Mini-Bayonet 24 VOLTS .035 AMPERES Clear .84 WATTS
1456	G4 1/2 Mini-Bayonet 18 VOLTS AMPERES Red WATTS
1895	G4 1/2 Mini-Bayonet 14 VOLTS .27 AMPERES Clear 3.78 WATTS

The following tables list selected light bulbs grouped by base style and globe shape/size. Each group is ordered by voltage.

The guides can be used to select light bulbs for layout structures or to determine a substitute bulb for a lighting accessory.

Accessory light bulbs may be substituted to operate the accessory at a different voltage or to reduce the heat generated. For example, replacing the 1445 (18 volts) bulb in an O22 track switch with a 1450 bulb (24 volts) will reduce generated heat and keep the switch lanterns from melting.

Consult the table for the appropriate base and globe shape/size.

Any Three-Rail Innovations' controller can be used to operate lighted accessories, lights in trackside accessories, or layout structure lighting. Each controller output can switch a number of bulbs, determined by dividing a controller's "Output Max Current" specification by the "Amperes" rating for the light bulb.

For example, a 1449 light bulb draws .2 amperes and a "Two Lighting Relays" controller's contacts can switch 8 amperes, or 40 type 1449 light bulbs.

A 2LR has two relays and each relay has two separate contacts, so a 2LR can switch 160 type 1449 light bulbs.

Consult the controller's specifications for "Output Max Current" values.