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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 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.

Related:

• Metric Hardware Specification Charts and Tables
• Screw Thread Size Chart
• ANSI, ISO Thread Designations and References
• Sheet Metal Self Threading ANSI Screws Dimensions for B and BP Thread
• Handbook of Manufacturing Processes
• ISO Metric Trapezoidal Screw Threads , Metric Hex Head Screws Bolts Sizes, British ISO Screw Threads