40
GAS-FIRED BOILER Boiler Manual
PART 8: FIELD WIRING
A. INSTALLATION MUST COMPLY WITH:
1. National Electrical Code and any other
national, state, provincial or local codes or
regulations.
2. In Canada, CSA C22.1 Canadian Electrical
Code Part 1, and any local codes.
B. FIELD WIRING
All connections made to the MOD CON boiler in
the field are done inside the electrical junction
box located on the side of the unit. The electri-
cal junction box is located on the left side of
MOD CON 500 and MOD CON 850 units and on
the right side of MOD CON 300 units. Multiple
knockout locations are available to route field
wires into and out of the electrical junction box.
The control used in the MOD CON series of boil-
ers is capable of directly controlling 2 pumps
when in standard mode and 3 pumps when con-
figured as a cascade master boiler. When con-
figured as a standard unit, each pump output
can provide a maximum of 3 amps at 120 volts.
If pumps used require more than this amount of
power, an external contactor or motor starter is
needed. If the boiler is configured as a cascade
master, the system pump output is a dry contact
output capable of switching 5 amps at 120 volts
in addition to the boiler pump and DHW pump
outputs sourcing 3 amps each.
The electrical junction box has separate, clearly
marked terminal strips for line voltage and low
voltage wiring. Special jacks are provided for
trouble-free cascade system wiring using stan-
dard CAT3 or CAT5 patch cables.
C. LINE VOLTAGE WIRING FOR
STANDARD BOILER
1. Connect the incoming power wiring to the
line voltage terminal strip in the electrical
junction box at terminals 120V, Neutral,
Ground (shown in figure 8-1.)
2. A line voltage fused disconnect switch may
be required to be externally mounted and
connected according to local codes that may
apply.
3. Connect the central heating pump as shown
in Figure 8-1 to the terminals marked BOILER
HOT, BOILER NEUT, BOILER GND. The
connections shown are suitable for a
maximum continuous pump draw of 3 amps
at 120 volts. If a the pump requires more
current or voltage other than the 120 volts
supplied, an external motor starter or
contactor will be required.
4. If using DHW, connect the domestic hot water
pump as shown in Figure 8-1 to the terminals
marked DHW HOT, DHW NEUT, DHW GND.
The connections shown are suitable for a
maximum continuous pump draw of 3 amps
at 120 volts. If a pump that requires more
current or voltage other than 120 volts
supplied, an external motor starter or
contactor will be required.
D. ALARM CONNECTIONS
1. The MOD CON control includes a dry contact
alarm output. This is an SPDT circuit, rated at
5 amps at 120 volts. This contact can be used
to activate an alarm light or bell or notify a
building management system if the boiler
goes into a lockout condition. The circuit
between the ALARM COM and NC terminals
is closed during normal operation and the
circuit between ALARM COM and NO is open
during normal operation. The connections
depicted in figure 8-1 shows two 120 volt
lights connected to the alarm terminals. One
light will be on when the boiler is in normal
n
WARNING
ELECTRICAL SHOCK HAZARD — For your
safety, turn off electrical power supply at service
entrance panel before making any electrical
connections to avoid possible electric shock
hazard. Failure to do so can cause severe
personal injury or death.
NOTICE
Wiring must be N.E.C. Class 1.
If original wiring as supplied with boiler must be
replaced, use only TEW 105 °C wire or
equivalent.
Boiler must be electrically grounded as required
by National Electrical Code ANSI/NFPA 70 —
latest edition.
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