Chromalox CXH-A-20 Installation And Operation Instructions Manual - Page 7

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Chromalox CXH-A-20 Installation And Operation Instructions Manual
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 damage.
Heater must be installed by a qualified person in ac-
cordance with the National Electrical Code, NFPA 70.
ELECTRIC SHOCK HAZARD. Any installation involv-
ing electric heaters must be performed by a quali-
fied person 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 frequency 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 be-
fore replacing cover. Do not use any gasket material
on joint surfaces.
2. Use copper conductors only for supply wires. Refer to
nameplate 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
stops 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 in-
sulated cable and fittings or rigid conduit and seal fittings
located as required by installation 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 thermostat 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 discon-
nect.
Table B -Supply Wiring Requirements
Model
kW
Phase
CXH-A-03
3
1
CXH-A-03
3
3
CXH-A-03
3
1
CXH-A-03
3
3
CXH-A-03
3
3
CXH-A-03
3
3
CXH-A-05
5
1
CXH-A-05
5
3
CXH-A-05
5
1
CXH-A-05
5
3
CXH-A-05
5
3
CXH-A-05
5
3
CXH-A-07
7.5
1
CXH-A-07
7.5
3
CXH-A-07
7.5
1
CXH-A-07
7.5
3
CXH-A-07
7.5
3
CXH-A-07
7.5
3
CXH-A-10
10
3
CXH-A-10
10
1
CXH-A-10
10
3
CXH-A-10
10
3
CXH-A-10
10
3
CXH-A-15
15
3
CXH-A-15
15
3
CXH-A-15
15
3
CXH-A-15
15
3
CXH-A-18
18
3
CXH-A-20
20
3
CXH-A-20
20
3
CXH-A-25
25
3
CXH-A-25
25
3
CXH-A-30
30
3
CXH-A-30
30
3
CXH-A-35
35
3
CXH-A-35
35
3
7. Installation must include appropriate over current protec-
tion 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 hazard-
ous location thermostat, a terminal block is provided for
connection (Figures 9 and 10). Remove the factory in-
stalled jumper across T2 and T3 on the terminal strip.
Wire the thermostat contact leads to these terminals. The
built in control transformer supplies the unit with either
24V or 120V for internal unit operation. 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).
7
Supply Wire
Max Fuse
Volts
90˚C Size (ga)
Amps
208
10
208
14
240
12
240
14
480
14
575
14
208
8
208
12
240
10
240
12
480
14
575
14
208
6
208
10
240
6
240
10
480
14
575
14
208
8
240
6
240
8
480
12
575
14
208
6
240
6
480
10
575
12
240
6
480
8
575
10
480
8
575
8
480
6
575
8
480
6
575
8
25
15
20
15
15
15
35
20
30
20
15
15
50
30
45
25
15
15
40
60
35
20
15
60
50
25
20
60
35
30
40
35
50
40
60
50