PURPOSE: To check

a) The minimum dimensions of the lampholder screw thread according to sheets 7004-21 and 7004-27.

b) Dimension X according to sheet 7005-20.

c) The machnical compatibility of the lamp holder with respect to lamps have adverse dimensions.

TESTING: It shall be possible to screw the threaded part of the gauge into the lampholder without using undue force (for the torque to be applied see publication 238, Sub-clause 4.4).

When the gauge has be screwed in as far as it will go, mark Y on the plunger shall be co-planar with mark A on the shaft.

The sleeve is then placed over the shaft of the gauge with its open end resting on the top edge of the screw shell of the holder. with the sleeve in this position, the plunger is pushed down as far as it will go.

Surface B of the gauge shall then lie between the marks X1 and X2 on the plunger or be co-planar with either of them; it shall not lie beyond them.