Guide to installation Smallest allowable bending radii for power and signal cables Conductor type Installation method solid, class 1/stranded, class 2 – carefully bent at connection – normal use stranded, class 5 (HUBER+SUHNER) – fixed – flexing Cable diameter D mm D ≤ 8 8 < D ≤ 12 12 < D ≤ 20 D < 20 2D 3D 4D 4D 4D 5D 6D 6D 3D 3D 4D 4D 4D 4D 5D 6D Allowable tensile stress 1. For installing cables by pulling on the conductors, or by drawing sleeve, the following max. pulling force (P) is allowed: P = 50 × A (N) A = Sum of conductor cross section (mm2) 2. When installing cables with high tensile armouring, the following max. pulling force (P) is allowed: P = 9 × D2 (N) D = cable diameter over armouring (mm) The calculation of pulling forces necessary for installation is done using the following formulas: Pulling force for installation of a straight section without elevation difference. P = 10 × G × L × µ with P: pulling force at the end of the stretch (N) G: weight of the cable (kg/m) L: length of the section (m) µ: coefficient of friction Pulling force for installation of a straight section with elevation difference P = 10 × G × (L × µ ± h) with h: elevation difference (m) Friction coefficient µ 0.15 – 0.30 installation with rollers 0.40 – 0.60 installation in cement pipes installation in plastic pipes 0.15 – 0.25 – with special lubricating grease 0.15 – 0.30 – with water N.B.: V ery long cables with thermoplastic sheaths can be pulled into plastic pipes with the aid of lubricants only. Local heating, occurring mainly in bends, may cause the cable to stick to the pipe wall. 80 HUBER+SUHNER Wires and cables
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