E
LECTRIC
D
UCT
H
EATER
•
I.O.M.
8
Electric Duct Heater IOM • ©June, 2001 • Environmental Technologies, Inc.
MINIMUM WIRE GAUGE
(from Table 310-16 NEC 1996 wire rated 75°C)
AMPERES
MINIMUM WIRE GAUGE
AMPERES
MINIMUM WIRE GAUGE
20
14 AWG
175
2/0 AWG
25
12 AWG
200
3/0 AWG
35
10 AWG
230
4/0 AWG
50
8 AWG
255
250 kcmil
65
6 AWG
285
300 kcmil
85
4 AWG
310
350 kcmil
100
3 AWG
335
400 kcmil
115
2 AWG
380
500 kcmil
130
1 AWG
420
600 kcmil
150
1/0 AWG
FIELD WIRING
NOTE:
Prior to installing any wiring, check the unit name plate for main power voltage, control voltage and maximum
overcurrent protection. Operating a heater at other than the specified voltage and phase can result in fire or electrical hazard.
All field wiring must comply with NATIONAL ELECTRIC CODE and local code requirements. A point-to-point wiring diagram is
located on the inside of the control panel door, which details wiring and field wire gauge.
• Use copper conductors only with a minimum of 75°C insulation.
• Tighten all wiring lugs and terminals prior to connecting power to the unit, as they may loosen during transportation.
• Connect the power lines to the power distribution terminals inside the control enclosure and tighten to 35 inch-pounds
(.4kg meters). If a factory wired disconnect switch is installed, connect the power lines to the line side of the switch. The line
block or disconnect is rated at 125% of nominal heater amperes based on 75°C wire.
• Mount and wire any field installed items as indicated on the factory supplied wiring diagram. When mounting field installed
components, do not jumper out or rewire any factory wiring without written approval from Environmental Technologies, Inc.
only. Violation will void warranty and listing.
• Energize unit and check all controls for proper operation. Do not operate unit without proper airflow.
ELECTRIC HEATER PREVENTATIVE MAINTENANCE CHECKS & SERVICE SCHEDULE
CAUTION!
D
ISCONNECT
A
LL
P
OWER
S
OURCES
B
EFORE
A
TTEMPTING TO
S
ERVICE OR
C
LEAN
H
EATER
Before, and at Midpoint of the Heating Season
:
• Check all electrical connections for tightness and broken terminations.
• Check all wiring for deterioration or over heating.
• Check unit for dirt or dust, and wipe clean (except elements).
• Check the element section for obstructions and debris.
• Check all components for wear and physical damage.
• Check all safety devices for proper operation.
• Check temperature controls for proper operation.
CAUTION:
In the event of thermal protection failure, it is recommended that a qualified service person
investigate the cause of failure prior to returning the heater to normal service.
POWER WIRING
CONTROL WIRING
TRANSFORMER WIRING
Stages
Primary Voltage (same as Power Wiring)
L1
Black
Step 1
Red
SECONDARY
L2
Red
Step 2
Purple
24 Volt
277 & 120 Volt
L3
Blue
Step 3
Orange
Negative
Yellow
Negative
Red
N
White
Step 4
Brown
Positive
Blue
Positive
Black
Ground
Green
Fan Output
Black
NOTE: Units with wire gauges
8 and greater will be color
coded with tape.
