Flexible non-metallic conduit systems

ADAPTAFLEX® FLEXIBLE NON-METALLIC CONDUIT SYSTEMS

— Technical section Cable carrying capacity (wire fill)

40% of the cross sectional area (CSA) - UK Wiring regulations BS7671 recommend that the total cross sectional area of the sum of individual cables shall not exceed 40% of the cross sectional area of the conduit based on 'using 3 or more cables'.

These instructions enable you to select the correct nominal diameter of non-metallic conduit, depending on the number and overall diameter of the cables to protect. Instructions to define the nominal diameter of a non-metallic conduit: • Step 1: Establish the number and size of each wire to be run in the conduit • Step 2: Look on the Cross Sectional Area (CSA) chart (table 1), look up the CSA taken up by each of the wires from Step 1 • Step 3: Add all the CSA values together (Total CSA) • Step 4: Look on the conduit fill value chart (table 2) and choose a conduit with a 40% fill value higher than the total CSA from Step 3

Example - What size of conduit to use? • Step 1: 4 x 2.5mm cables, 2 x 10mm cables, and 3 x 25mm cables • Step 2: - The CSA of Four 2.5mm cables is 19.64 (4 x 4.91) - The CSA of Two 10mm cables is 157.08 (2 x 78.54) - The CSA of Three 25mm cables is 1472.61 (3 x 490.87) • Step 3: Total of these groups is 19.64 + 402.12 + 1472.61 = 1649.33 • Step 4: Using Table 2, we chose the size of non-metallic conduit with 40% fill value higher than 1649.33: 106mm NOTE: The information given above relates to PA - Standard weight conduit and Adaptalok fittings. It is given in good faith and should be used only as a guide in conjunction with the relevant wiring regulations.

— Table 2 - Wire fill of non-metallic conduit

— Table 1 - Cross Sectional Area (CSA) chart

Nominal diameter (mm)

100% fill value

40% fill value

Overall Diameter [mm]

Cross sectional area (CSA) [mm 2 ]

CSA [mm 2 ]

10 13 16 18 21 28 34 42 54 80

33.2 72.4

13 29 44 63 86

0.79 1.77 4.91

109.4 158.4 213.8 369.8 602.6 973.1

1.5 2.5

4 6

12.57 28.27 78.54

148 241 390 680

10 16 25 35 50

201.06 490.87 962.11 1963.50

Conductor diameter

1698.2

3520 6500

1410 2600

Overall diameter

106