Practicals & House Lights

Ever wonder what that letter or two on a lamp means?

A – Arbitrary (Standard)

B/BA – Bulged, Bulged with angular tip

C – Conical
CA – Candle shape with bent tip
E/ED – Elliptical, Elliptical with dimple in the crown
F – Flame
G – Globe
H – lantern chimney
MR – Multi-Faceted Reflector
P – fancy round
PS – Pear Shape
S – Sign, straight-sided shape (compare with CA and BA)
T – Tubular
BT – Bulged Tubular
ST – Spherical Tubular
R – Reflector
BR – Bulbous Reflector
ER – Elliptical Reflector
PAR – Parabolic Aluminized Reflector
AR – Aluminized Reflector
RP – Reflector, Pear shape

Common Incandescent Lamp Shape Codes 

General Service 
Light emitted in (nearly) all directions. Available either clear or frosted. 
Types: General (A) arbitrary, (mushroom shaped standard household light bulb), (E) elliptical, (S) sign, (T) tubular
Common sizes: A17, 19 and 21
High Wattage General Service 
Lamps greater than 200 watts. 
Types: (PS) Pear-shaped
Decorative lamps used in chandeliers, and decorative fixtures with visible lamps. Smaller candle-sized lamps often use a smaller socket. 
Types: (B) candle, (CA & BA) twisted candle, bent-tip candle, (F) flame, (G) globe, (H) lantern chimney, (P) fancy round 
Reflector (R) 
Reflective coating inside the bulb directs light forward. Flood types (FL) spread light. Spot types (SP) concentrate the light. Reflector (R) bulbs put approximately double the amount of light (foot-candles) on the front central area as General Service (A) of same wattage. 
Types: (R) Standard reflector, (BR) bulged reflector, (ER) elliptical reflector, and crown-silvered. Crown silvered light bulbs reflect the light from the lamp back into the fitting which contains a reflector.
Common sizes: R16, 20, 25 and 30 
Parabolic Aluminized Reflector (PAR) 
Parabolic Aluminized Reflector (PAR) lamps control light more precisely. They produce about four times the concentrated light intensity of general service A lamps, and are used in recessed and track lighting. Weatherproof casings are available for outdoor spot and flood fixtures. 
Common sizes: PAR 16, 20, 30, 38, 56 and 64 

Available in numerous spot and flood beam spreads. Like all light bulbs, the number represents the diameter of the bulb in 1⁄8 of an inch. Therefore, a PAR 16 is 51 mm (2 in) in diameter, a PAR 20 is 64 mm (2.5 in) in diameter, PAR 30 is 95 mm (3.75 in) and a PAR 38 is 121 mm (4.75 in) in diameter.  

Multifaceted reflector (MR) Multifaceted reflector lamps are usually smaller in size and run at a lower voltage, often 12 V.