identify your lightbulb > bulb identification key


STEP 4: Light Bulbs with Bases That Have 2 or 3 to 4 Threads
[Short Threaded Bases]

Select the option most resembling your bulb from the drop-down menu to proceed to the next step. Please consult "option descriptions" for detailed info.


[The drop-down menu can be re-set by refreshing your browser window.]


FULL OPTION DESCRIPTIONS / IMAGE GLOSSARY: [Option titles are also linked to proceed to the next step.]


OPTION A: Bulb has large, bulky base with copper screw shell (over wood insulator) that has 2 to 3 threads, a cone shaped copper terminal (also over wood), and a large wooden collar (for holding and twisting bulb into a socket).  Wood is cemented to the neck of bulb by plaster of paris. [710a]


OPTION B: Bulb has a less bulky, smaller base with a copper screw shell (over wood insulator) that has 2 to 3 threads, a cone shaped copper terminal (also over wood), and a smaller wooden collar (for holding and turning bulb).  Wood is cemented to the neck of bulb by plaster of paris. [710b]


OPTION C: Base of bulb is similar to that of shown in thumbnail above [see A65] except wood is eliminated and entire insulator is made of plaster of paris. (NOTE: Plaster of paris is white in color, somewhat rough and porous, and easy to scratch.)  Bulb consists of smaller base with copper screw shell (over plaster of paris insulator) that has 2 to 3 threads, a cone shaped copper terminal (also over plaster of paris), and a smaller collar (for holding and turning bulb) also made of plaster of paris. [710c]

OPTION D: Bulb is similar to that of shown in thumbnail above (entire threaded base is over plaster of paris) except cone-shaped copper ring is now eliminated.  Bulb has a copper screw shell with 2 to 3 threads and one straight-sided copper contact terminal on end of base all over plaster of paris insulator.  Bulb also has a small collar made of plaster of paris for twisting bulb into socket.  (NOTE: plaster of paris is white in color, somewhat rough and porous, and easy to scratch.) [710d]


OPTION E: Bulb is similar to that of shown in thumbnail above (Figure 30b) except collar is now eliminated.  Base of bulb has copper screw shell with 2 to 3 threads and one copper contact terminal sticking out from end of base, all over plaster of paris insulator. (NOTE: plaster of paris is white in color, somewhat rough and porous, and easy to scratch.) [710e]




Pathway History:
START
2 || Tipped-Bulb-Options
3 || Base-Shape
4 || Bulbs-With-2-3-4-Threads

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