Chromalox DU-RAD-458 6.04 757 Wiring, ELECTRICAL CONNECTIONS - A.End Elements, B.Center Elements

WIRING

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 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.The power supply voltage should be the voltage as specified on the heater nameplate located on the heater housing.

2.Wiring should be run in flexible or rigid metal conduit and must be installed in accordance with the requirements of the National Electrical Code and such other local requirements as may be applicable. Note: High temperatures will oxidize copper. Do not use copper wire in connecting this heater. Nickel-plated copper wire, insulated in accordance with requirements for temperature and voltage is recommended.

3.A sufficient length of this wire (not less than 12”) should be used to extend from each heater terminal into a connection box location where the temperature does not exceed 300˚F.

4.ELECTRICAL CONNECTIONS —

A.End Elements

Electrical connection to the heater end elements is made through the 7/8” dia. opening in the end of the terminal cover of the element assembly. A 1/2” flexible conduit connector is provided with each element assembly for this purpose.

B.Center Elements

Electrical connection to the heater center element is made through the 7/8” dia. opening in the 4” octagon conduit box for the element assembly. A 1/2” flexible conduit connector is pro- vided with each element assembly for this purpose.

5.ACCESS TO TERMINALS

A.End Elements

Access to the end element terminals is obtained by removing the mounting bolt, nut and spacer (see Figure 9, items 9, 16 and 18) and sliding the terminal end of the element assembly out of the housing.

B.Center Elements

Access to the center mounted element terminals is obtained by removing the terminal box cover.

6.END ELEMENT TERMINAL ASSEMBLY

Assemble end terminal, screw and wire as shown in Figure 5. Hold terminal with pliers and tighten the terminal screw securely with a screwdriver.

Figure 5 — End Element Terminal Assembly

7.CENTER ELEMENT TERMINAL ASSEMBLY

Assemble center terminal, washers, nut and wire as shown in Figure 6. Hold terminal with pliers and tighten the terminal nut securely with a wrench.

Figure 6 — Center Element Terminal Assembly

CAUTION: Terminal clip is spot-welded to element terminal pin and over-tightening terminal screw may break the weld or shear off terminal pin. However, either the screw or nut should be suffi- ciently tightened to eliminate arcing.

8.SERIES CONNECTION of Radiant Heaters of equal volt and watt rating is permitted in all line voltages up to 600 volts. In mak- ing such series connections it is necessary to observe the “right” (series-parallel) connection rather than the “wrong” (parallel- series) connection both shown in Figure 7. If heaters are connect- ed according to the “wrong” illustration, failure of any heater will cause progressive failure of other heaters still operating.

Wrong	Right
Radiant
Heaters
L1	L1
L2
	L2

Figure 7

9.DELTA CONNECTIONS — When heaters occur in multiples of three, they may be connected to, and balanced across, three-phase lines. The most commonly used connection is the delta connection illustrated in Figure 8.

Wrong	Right
Radiant
Heaters
L1	L1
L2
	L2

Figure 8

Three phase Delta connections to minimize inductive effect in conduits are made per this diagram. The rule: run all 3 three-phase conductors in the same conduit as far as possible. For single-phase, run only two conductors and follow the same rule.

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