Watlow FIREBAR Screw Plug - Manual (Page 4)

WATLOW IND.
FIREBAR® Screw Plug Installation & Maintenance Manual
I&M NUMBER: 316-42-3-1 Page: 4
Date: 6/11/2008 Rev: 2.00
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WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE 573-221-2816 n FAX 573-221-3723
DANGER: HAZARD OF FIRE. Electric heaters are capable of developing high temperatures so extreme
care should be taken to locate heaters in safe environments. Mounting heaters in atmospheres
containing combustible gases and vapors should be avoided. According to article 501 of the NEC, the
maximum surface temperature of the heater shall not exceed 80 % of the auto-ignition of the surrounding
atmosphere when the heater is continuously energized. Care should also be taken to keep combustible
materials far enough away to be free of the effects of high temperatures.
5. Wiring
WARNING; HAZARD OF ELECTRIC SHOCK. Any installation involving electric heaters must be
grounded to earth to eliminate shock hazard.
Electrical wiring to the heaters must be installed in accordance with the National Electric Code and any
state and local electrical code by qualified personnel.
Consult wiring diagram supplied with the unit for correct feeder or leadwire connections. If wiring
diagram is not supplied, the factory should be consulted for the appropriate wiring diagram. Feeder wire
should be properly selected based on amperage, electrical power rating, ambient temperature, and type
of environment. Feeder wire should also be housed in either rigid or flexible conduit which carries the
same classification as the heater enclosure. It is the users responsibility to properly size and install
feeder wire.
Feeder wire line connections are to be made directly to stud terminals where terminals are supplied. Use
a ring terminal (T&B, Amp, etc.) for making these connections. It is essential that these connections be
tight. When tightening termination, the bottom nut should be supported while applying a maximum torque
of 20 in-lbs to the top nut. In some cases leadwires may be provided. Ground connection (color coded
"green") is supplied inside the housing for ground wire.
Line voltage must be equal to or less than rating stamped on the heater assembly. Some units are
supplied as dual voltage . Example: 240V / 480V, check wiring diagram supplied with the unit to make
sure which scheme was used. In most cases (unless specified by customer) units are wired for the
higher voltage.
Thermostats can be supplied with Screw Plug heaters. Consult the wiring diagram supplied with the
heater for the suggested wiring of thermostats. For safe operation of thermostats, consult Installation and
Maintenance manual for thermostats that is attached.
Thermostats should not be used as an "OFF" device; the use of a disconnect switch or circuit breaker is
recommended. The disconnect switch will allow isolation of the heater when maintenance of the heater
is required.
Start Up
Before energizing the heater the following items should have been checked with the heater power
disconnected:
1. Immersed section of heater is completely covered by liquid
2. Electrical termination is tight and wiring is per wiring diagram supplied with heater
3. Proper disconnecting means and fusing have been installed
4. The voltage rating of the heater is the same as that being applied
5. Megohm is within acceptable limits
6. Proper temperature controls and safety limiting devices are in place
7. Heater is securely installed in tank header and no leaks are visible