PW LADDER TRAY THERMAL CONTRACTION AND EXPANSION Expansion Splice Plate Installation It is important that thermal contraction and expansion be considered when installing cable tray systems. The length of the straight cable trays runs and the temperature differential govern the number of expansion splice plates required (see Table 1). Proper operation of the expansion splice plates depends upon correct placement of the tray supports, hold down clamps and expansion guides as shown. Hold Down Clamps should be used at the support point nearest to the midpoint between expansion gaps. Expansion Guide Clamps should be used at all support points other than the midpoint. These clamps should be installed in such a way to allow the tray to slide freely under the clamp when thermal contraction and expansion takes place. Itray supports with expansion guide clamps may be located at 1/4 span. For all other product lines, supports with expansion guide clamps should be located within 24 " of each side of expansion splice plates. Reference Figures 2a and 2b on catalog page B.9 Accurate gap settings between trays at the expansion joint at the time of installation are necessary for the proper operation of the expansion splice plates. Use the following procedure to determine the correct gap setting: A B C D Determine what the maximum temperature will be at the installation location and plot this point on the graph on the max. temp line. (Example value = 100) Determine what the minimum temperature will be at the installation location and plot this point on the graph on the min. temp line. (Example value = -30). Draw a line between the maximum and minimum points. At the time of installation, determine the air temperature. (Example = 50). Plot this point on the line drawn between the maximum and minimum temperatures to determine the correct gap setting at the expansion plate. (Example = 3 /8 " ). Table 1 TEMPERATURE DIFFERENTIAL ˚F 25 50 75 100 125 150 175 Maximum Temperature 130 110 90 70 50 30 10 -10 -30 oC o 50 40 30 20 10 -10 -20 -30 -40 1/8 F A ˚C 14 28 42 56 70 83 97 MAXIMUM SPACING BETWEEN A 260 130 87 65 52 43 37 EXPANSION JOINTS FOR 1 " MOVEMENT (FT.) M G L T 512 256 171 128 102 85 73 F 667 333 222 167 133 111 95 Figure 1 Gap Setting of Expansion Splice Plate Minimum Temperature oC oF C 130 110 90 70 50 30 10 -10 -30 D 1/4 3/8 1/2 5/8 3/4 7/8 Gap Setting (in) 1 B 50 40 30 20 10 -10 -20 -30 -40 A B C D B.8 WWW.LEGRAND.US/CABLOFIL INTRODUCTION Metal Temperature At Time Of Installationhttp://WWW.LEGRAND.US/CABLOFIL