(2) Loosen thumbscrew (3, fig. 4-7) to release
upper carbon (5) from upper carbon holder (2) and upper arm
(3) Loosen thumbscrew (3) of lower carbon holder
(10) and lower arm (9), and remove lower carbon (8).
(1) Replace upper carbon (5) between upper
carbon holder (2) and upper arm (4), positioning the carbon
so that approximately 8 inches exist from carbon end to
(2) Tighten thumbscrew(3), being absolutely sure
the carbon is securely clamped and not cocked.
(3) Replace lower carbon (8, fig. 4-7) between
lower carbon holder (10) and lower arm (9), positioning the
carbon so that its length from end to holder matches length of
d. Adjusting. Move the upper arm (4) down so that
upper carbon (5) and lower carbon ends meet at the center of
the reflector. Reclamp carbons on holders if carbons ends
are not flush and centered, or if unequal carbon lengths are
When installing burned-off carbons, make
certain they are approximately the same length, and that they
are adjusted in the holders to meet at the center of the
reflector. Avoid removal of carbons from arc lamps when hot
or warm, as serious burns will result. Wait until carbons cool.
Figure 4-7. Inside view of arc lamp.