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ELECTRICAL WIRING
Models 51-2, 51-S-2 and 53-2
TOOLS NEEDED:
One (1) flathead screwdriver.
• To prevent electrical shock, turn off the electrical power before making electrical connections.
• This low water cut-off must be installed in series with all other limit and operating controls installed on the
boiler. After installation, check for proper operation of all of the limit and operating controls, before leaving
the site.
Failure to follow this warning could cause electrical shock, an explosion and/or a fire, which could result in
property damage, personal injury or death.
a. The No. 2 switch can be positioned with the
conduit opening facing toward or away from
the float chamber. These are the only positions
in which the switch will function properly.
See drawing at right.
b. On initial fill-up, push the 2M manual reset
button after the proper water level is reached
to energize the burner. If a low water condition
occurs and the water level has been restored,
push the reset button to energize the burner.
c. Follow the wiring diagrams below to wire the
No. 2 Switch. Terminals C and NC are the low
water cut-off switch. Terminals C and NO are
alarm switch. If the electrical load exceeds the
rating of the switch, use an auxiliary relay or
motor starter.
SCHEMATIC OF SWITCH OPERATION
Low
Water
Alarm
Terminals
C.
N.O.
N.C.
Water Level Normal
Burner On
Alarm Off
!
WARNING
C.
Low Water
N. O.
Cut-Off
N.C.
Terminals
C.
N.O.
N.C.
Water Level Low
Burner Off
Alarm On
Conduit opening facing
toward float chamber
Conduit opening facing
away from float chamber
Manual reset button
on No. 2m Switch
USED AS A MAIN LINE SWITCH
AND/OR LOW WATER ALARM
Neutral
120 V.A.C.
Supply Hot
C.
N. O.
N.C.
USED AS A PILOT SWITCH TO COIL
OF RELAY OR MOTOR STARTER
C.
N.
O.
N.C.
Low
Water
Alarm
Burner
Circuit
Line
Load
5
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