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LAMP SIZE
(shown in actual size)
Lamp size is determined by the maximum diameter
expressed in eighths of an inch (1/8"). For example:
an A19 lamp is 19-eighths of an inch or 19/8" in diameter.
To determine a lamp size, use the full size scale shown
(calibrated in eighths). Place one edge of the lamp to
be identified on the top edge of the scale and measure
the approximate diameter by reading the scale at the
opposite edge of the lamp. Sizes of the more popular
lamp types are indicated on the scale.
GLASS BULB
CEMENT
BOTTOM CONTACT
GLASS INSULATOR
GLASS STEM
FILAMENT
SUPPORT
TUNGSTEN
FILAMENT
VACUUM OR
ARGON-NITROGEN
GAS MIXTURE
LEAD-IN WIRES
EXHAUST
TUBE
METAL BASE
FUSE
INCANDESCENT LAMP
COMPONENTS
5
4
3
1
2
INCHES 8THS
33
34
36
37
39
26
27
28
29
31
18
22
9
11
13
1
2
3
4
5
6
7
1/4
1/2
3/4
T6
T12
A19
PS25
BR30
BR38
G40
T10
7
6
49
50
51
52
53
54
55
42
43
44
45
46
47
S14
A15
R20
A21
A23
G25
PS30
PS35
BR40 PS40
T5
T8
1
2
INCANDESCENT LAMP
SIZE REFERENCE
INCANDESCENT LAMPS
47
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