Qmark GUX - Explosion Proof Unit Heaters - Manual (Page 5)

5
WIRING AND WIRING DIAGRAMS
ELECTRIC SHOCK HAZARD. Disconnect all power
before installing or servicing heater. Failure to do
so could result in personal injury or property dam-
age. Heater must be installed by a qualified person
in accordance with the National Electrical Code,
NFPA 70.
ELECTRIC SHOCK HAZARD. Any installation involving
electric heaters must be performed by a qualified per-
son and must be effectively grounded in accordance
with the National Electrical Code to eliminate shock
hazard.
1. Loosen and remove bolts securing the main terminal enclosure
cover on side of unit. Connect heater to line supply wires at the
box lugs located on the contactor according the voltage and fre-
quency specified on the nameplate (see Figure 9). Refer to the
appropriate wiring diagram which also appears on the inside
cover of this enclosure (see Table B and diagrams on page 6).
Explosion Hazard. Cover joints must be clean
before replacing cover. Do not use any gasket
material on joint surfaces.
2. Use copper conductors only for supply wires. Refer to name-
plate and Table B for size and rating required.
3. Connect supply line ground conductor to the box lug provided
on the base plate below contactor input lugs.
4. The fan motor is factory wired at the same voltage, and phase as
the heating elements. All motors are thermally protected and
connected to the main supply contactor. On three phase units, it
is necessary to verify that the fan rotation is correct. Air
stream discharge must be out front of unit. After connecting unit
to line and closing all covers tightly, energize unit momentarily.
If air does not exit front louvers, reverse any two supply leads at
the box lugs on the contactor or at the supply disconnect.
5. Either of two 1 NPT rigid conduit openings with integral stop
may be used for connection to supply line. (See Figure 9 and
10 for locations) Use only NEC approval hazardous locations
means of wiring such as mineral insulated cable and fittings or
rigid conduit and seal fittings located as required by installa-
tion codes.
Explosion Hazard. All unused conduit openings must
be fitted with plugs that are U.L. recognized for use
in hazardous locations.
6. Heaters may be provided with a built-in control switch and/or
thermostat. If not, they should be controlled by an externally
mounted disconnect switch and/or separately mounted thermo-
stat as shown in the appropriate wiring diagram on page 6. In
case of malfunction, the personnel in the area should be aware
of location of heater disconnect.
7. Installation must include appropriate over current protection
devices (fusing or circuit breakers) as required by the National
Electric Code in the supply line to the unit. Refer to nameplate
for proper current ratings.
8. To operate heaters from an externally mounted hazardous loca-
tion thermostat, a terminal block is provided for connection
(Figures 9 and 10). Remove the factory installed jumper across
T2 and T3 on the terminal strip. Wire the thermostat contact
leads to these terminals. The built in control transformer sup-
plies the unit with either 24V or 120V for internal unit opera-
tion. This voltage will appear across the thermostat contacts
when they are open. The minimum thermostat contact rating
should be 1 amp @ 120 VAC. Refer to nameplate for control
voltage of unit. The 1/2 NPT conduit wiring entry on top of the
terminal enclosure should be used to wire the thermostat to the
heater (Figure 10).
9. Protection against overheating is provided by a manual reset
limit control located within the heat exchanger wiring com-
partment. (Figure 9) Activation of the control will open the
control circuit and energize the pilot lamp (if supplied). If nor-
mal airflow is restricted, or stopped, the unit will be cycled off
by the manual reset cutout. The manual reset limit control is
also designed to shut down the unit completely if the fluid
level is low or other heater malfunction occurs.
Manual reset limit control must never be bypassed
in the control circuit. If the limit actuates, shut
down unit and investigate cause of abnormal oper-
ation. Do not reenergize until the problem has
been corrected.
The system designer is responsible for the safety
of this equipment and should install adequate
back-up controls and safety devices with their
electric heating equipment. Where the conse-
quences of failute could result in personal injury or
property damage, back-up controls are essential.
Supply Wire
90°C Size Max Fuse Wiring
kW Phase Volts (ga) Amps Diagram #
1 208 10 25 I
3 208 12 15 II
3
1 240 10 20 I
3 240 12 15 II
3 480 12 15 II
3 575 12 15 II
1 208 8 35 I
3 208 10 20 II
5
1 240 8 30 I
3 240 10 20 II
3 480 12 15 II
3 575 12 15 II
1 208 6 50 I
3 208 8 30 II
7.5
1 240 6 45 I
3 240 8 25 II
3 480 12 15 II
3 575 12 15 II
3 208 8 40 II
1 240 4 60 I
10 3 240 8 35 II
3 480 10 20 II
3 575 12 15 II
3 208 4 60 II
15
3 240 6 50 II
3 480 8 25 II
3 575 10 20 II
18 3 240 4 60 II
20
3 480 8 35 II
3 575 8 30 II
25
3 480 8 40 II
3 575 8 35 II
30
3 480 6 50 II
3 575 8 40 II
35
3 480 4 60 II
3 575 6 50 II
Table B – Supply Wiring Requirements