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Light Lamp Socket Threads Table

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Light Lamp Socket Threads Table

Lamp Base and Socket Shell Threads.—The “American Standard” threads for lamp base and socket shells are sponsored by the American Society of Mechanical Engineers, the National Electrical Manufacturers’ Association and by most of the large manufacturers of products requiring rolled threads on sheet metal shells or parts, such as lamp bases, fuse plugs, attachment plugs, etc. There are five sizes, designated as the “miniature size,” the“candelabra size,” the “intermediate size,” the “medium size” and the “mogul size.”

Rolled Threads for Screw Shells of
Rolled Threads for Screw Shells of Electric Sockets and Lamp Bases
American Standard

Male or Base Screw Shells Before Assembly
Size
Threads
per Inch
Pitch P
Depth of
Thread D
Radius Crest
Root R
Major
Dia.
Minor
Dia.
Max.
A
Min.
a
Max.
B
Min.
b
Miniature
14
0.07143
0.020
0.0210
0.375
0.370
0.335
0.330
Candelabra
10
0.10000
0.025
0.0312
0.465
0.460
0.415
0.410
Intermediate
9
0.11111
0.027
0.0353
0.651
0.645
0.597
0.591
Medium
7
0.14286
0.033
0.0470
1.037
1.031
0.971
0.965
Mogul
4
0.25000
0.050
0.0906
1.555
1.545
1.455
1.445
Socket Screw Shells Before Assembly
Miniature
14
0.07143
0.020
0.0210
0.3835
0.3775
0.3435
0.3375
Candelabra
10
0.10000
0.025
0.0312
0.476
0.470
0.426
0.420
Intermediate
9
0.11111
0.027
0.0353
0.664
0.657
0.610
0.603
Medium
7
0.14286
0.033
0.0470
1.053
1.045
0.987
0.979
Mogul
4
0.25000
0.050
0.0906
1.577
1.565
1.477
1.465

All dimensions are in inches.

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