MagnaTherm Boilers and Water Heaters
Page 33
SECTION 8 Electrical
Connections
8.A Installation Warnings
CAUTION
The supply voltage to this unit must not be
disconnected, except for service or isolation,
or unless otherwise instructed by procedures
outlined in this manual. To signal a call for heat,
use the 24V field interlock, as shown in the
wiring diagram.
DO NOT MAKE AND BREAK THE LINE
VOLTAGE TO THE UNIT TO SIGNAL A CALL
FOR HEAT. A call for heat/ end call for heat
MUST be connected to the field interlock
terminals. Some components are designed to
have constant voltage during normal operation.
If the units supply voltage is toggled as a call
for heat signal, premature failure of these
components may result.
The unit does not recognize 4mA as a signal
to shut off. If the call for heat is not connected
between the field interlock terminals, the unit
will remain in low fire when it sees 4mA as a
modulating signal.
This unit is provided with an electrical junction box
in the rear panel for main power connections. See
Figure 18 on page 35. All power wires are factory
installed between this junction box and the Main
High Voltage Box at the front of the unit. The unit
is available with multiple voltage packages to adapt
to customer needs ranging from 120-600 volts with
single or 3 phase versions. Refer to the rating plate
for appropriate voltage and current ratings.
See Table 20
As a common industry practice, the manufacturer
has color coded the single and three phase wires.
On single phase models, the incoming voltage will
be protected by the appropriate circuit breaker, sized
and installed by a qualified Electrician/authorized
personnel. The 120 volt and 24 volt systems will be
protected with resettable fuses mounted in the top
of the high voltage box. The 24 volt transformer is
also redundantly protected by its integrated 4 amp
resettable fuse.
On three phase models, a step down transformer
(which is protected using an appropriate din rail
mounted circuit breaker) generates 120 volt single
8.B Main Power Connections
phase to power the 24 Volt Transformer. The 120
volt and 24 volt outputs of either transformer are
protected with resettable fuses mounted in the top
of the high voltage box. The 24 volt transformer is
also redundantly protected by its integrated 4 amp
resettable fuse.
All power connections must be run through the
back panel as shown in Figure 18.
CAUTION
Label all wires prior to disconnection when
servicing controls. Wiring errors can cause
improper and dangerous operation. Verify proper
operation after operation servicing.
ATTENTION
Au moment de l’entretien des commandes,
étiquetez tous les fils avant de les débrancher.
Les erreurs de câblage peuvent nuire au bon
fonctionnement et être dangereuses. S’assurer
que l’appareil fonctionne adéquatement une fois
l’entretien terminé.
WARNING
The unit must be electrically grounded in
accordance with the requirements of the authority
having jurisdiction or, in the absence of such
requirements, with the latest edition of the National
Electrical Code, ANSI/NFPA 70, in the U.S. and
with the latest edition of CSA C22.1 Canadian
Electrical Code, Part 1, in Canada. Do not rely
on the gas or water piping to ground the metal
parts of the unit. Plastic pipe or dielectric unions
may isolate the unit electrically. Service and
maintenance personnel, who work on or around
the unit, may be standing on wet floors and
could be electrocuted by an ungrounded unit.
Electrocution can result in severe injury or death.
Single pole switches, including those of safety
controls and protective devices, must not be wired
in a grounded line.
All electrical connections are made on the terminal
blocks that are located inside the control panel.
All internal electrical components have been
prewired. No attempt should be made to connect
electrical wires to any other location except the
terminal blocks.
