Teledyne Battery-Backed Power Supply Installation And Operation Manual page 10

Battery-Backed Power Supply
1.2.1 Connection to a Power
Source
Figure 1-1 Battery-Backed Power Supply, Models 914 (left) and 924 (right)
1-2
Model 914 – The Model 914 Battery-Backed Power Supply is
intended for use on a 120 VAC, 60 Hz circuit and is equipped
with a three-prong standard grounded plug (sketch A, Figure
1-2). It must be used with a three-slot grounded outlet (sketch
B). A temporary adaptor, as seen in sketch C, may be used to
connect this plug to a two-wire receptacle (sketch D) if the correct
grounded outlet is not available. The temporary adaptor should
be used only until a proper outlet can be installed by a qualified
electrician.
Before using the grounding adaptor as
illustrated, make certain that the center screw in
the outlet plate is actually grounded. This may be
done by testing for voltage between the hot side
of the outlet (narrower blade) and the outlet plate
screw. Do not use the adaptor if the outlet box is
not grounded.
Use a volt meter or neon test lamp to test for grounding. Make
sure the screw is still grounded after the adaptor is installed.
Some outlet plates have very short screws and some even use
plastic screws. While modern conduit systems are usually
properly grounded, older two-wire systems may only be grounded
at the main switch, and deterioration over time can make
grounding of thin wall conduit unreliable. This is particularly
true where moisture, heat, vibration, or chemical agents in the
air may weaken the junctions between the conduit fittings and
thin wall conduit. There may be no bare copper drain wire inside
the conduit. (Not all codes require the drain wire.) The adaptor
must not be used if this is the case. Have an electrician install a
proper grounding outlet or run a ground wire to the nearest cold
water pipe.
Model 924 – The Model 924 Battery-Backed Power Supply is
intended for use on a 240 VAC, 60 Hz circuit.
DANGER