Cable Installation
Cable Pulling Tension
Route based cable pulling tension calculator
Engineering basisIEEE 1185-2019 installation practiceSouthwire route tension equationsManufacturer limits remain authoritative
FORMULAS USED
Horizontal straight
Tout = Tin + w*mu*W*L
Tout = Tin + w*mu*W*L
Inclined straight, pulling up
Tout = Tin + W*L*(sin(a)+w*mu*cos(a))
Tout = Tin + W*L*(sin(a)+w*mu*cos(a))
Inclined straight, pulling down
Tout = Tin - W*L*(sin(a)-w*mu*cos(a))
Tout = Tin - W*L*(sin(a)-w*mu*cos(a))
Horizontal bend
Tout = Tin*cosh(w*mu*a)+sinh(w*mu*a)*sqrt(Tin^2+(W*R)^2)
Tout = Tin*cosh(w*mu*a)+sinh(w*mu*a)*sqrt(Tin^2+(W*R)^2)
Allowable conductor tension
Tcable = if(N<=3,N,0.8*N)*S*A*mm2_to_cmil*lbf_to_n
Tcable = if(N<=3,N,0.8*N)*S*A*mm2_to_cmil*lbf_to_n
μ : Dynamic coefficient of frictionAfter Calculate
W : Cable assembly weight force per metreAfter Calculate
w : Weight correction factorCalculated after submit
θ / φ : Straight slope / bend angledegrees entered, radians used internally
R : Bend radiusm
Formulas
Calculation Methods
Horizontal straightTout = Tin + w*mu*W*LSouthwire Power Cable Installation Guide, E-7
W is cable assembly weight force per unit length.
W is cable assembly weight force per unit length.
Inclined straight, pulling upTout = Tin + W*L*(sin(a)+w*mu*cos(a))Southwire Power Cable Installation Guide, E-8
θ is the straight section angle from horizontal.
θ is the straight section angle from horizontal.
Inclined straight, pulling downTout = Tin - W*L*(sin(a)-w*mu*cos(a))Southwire Power Cable Installation Guide, E-9
θ is the straight section angle from horizontal.
θ is the straight section angle from horizontal.
Horizontal bendTout = Tin*cosh(w*mu*a)+sinh(w*mu*a)*sqrt(Tin^2+(W*R)^2)Southwire Power Cable Installation Guide, E-10
φ in radians, R bend radius.
φ in radians, R bend radius.
Vertical concave up bend, pulling upTout = Tin*exp(w*mu*a)-(W*R/(1+(w*mu)^2))*(2*w*mu*sin(a)-(1-(w*mu)^2)*(exp(w*mu*a)-cos(a)))Southwire Power Cable Installation Guide, E-11
Exact route equation from manufacturer installation guide.
Exact route equation from manufacturer installation guide.
Vertical concave up bend, pulling downTout = Tin*exp(w*mu*a)-(W*R/(1+(w*mu)^2))*(2*w*mu*exp(w*mu*a)*sin(a)+(1-(w*mu)^2)*(1-exp(w*mu*a)*cos(a)))Southwire Power Cable Installation Guide, E-12
Exact route equation from manufacturer installation guide.
Exact route equation from manufacturer installation guide.
Vertical concave down bend, pulling upTout = Tin*exp(w*mu*a)+(W*R/(1+(w*mu)^2))*(2*w*mu*exp(w*mu*a)*sin(a)+(1-(w*mu)^2)*(1-exp(w*mu*a)*cos(a)))Southwire Power Cable Installation Guide, E-13
Exact route equation from manufacturer installation guide.
Exact route equation from manufacturer installation guide.
Vertical concave down bend, pulling downTout = Tin*exp(w*mu*a)+(W*R/(1+(w*mu)^2))*(2*w*mu*sin(a)-(1-(w*mu)^2)*(exp(w*mu*a)-cos(a)))Southwire Power Cable Installation Guide, E-14
Exact route equation from manufacturer installation guide.
Exact route equation from manufacturer installation guide.
Weight correction, one cablew = 1Southwire Power Cable Installation Guide, E-16
Single cable.
Single cable.
Weight correction, triangularw = 1/sqrt(1-(d/(D-d))^2)Southwire Power Cable Installation Guide, E-17
Also used conservatively for two cables.
Also used conservatively for two cables.
Weight correction, cradledw = 1+(4/3)*(d/(D-d))^2Southwire Power Cable Installation Guide, E-18
Three cables with D/d ≥ 2.5.
Three cables with D/d ≥ 2.5.
Weight correction, complexw = 1.4Southwire Power Cable Installation Guide, E-19
Four cables or more.
Four cables or more.
Allowable conductor tensionTcable = if(N<=3,N,0.8*N)*S*A*mm2_to_cmil*lbf_to_nSouthwire Power Cable Installation Guide, E-4 to E-6
A is conductor area in circular mil for this manufacturer engineering method.
A is conductor area in circular mil for this manufacturer engineering method.
Maximum allowable pullTallow = min(limit_a,limit_b)Engineering installation limit selection
Use manufacturer ratings for the actual cable, pulling eye/grip, rope, puller and anchors. Blank optional limits are ignored.
Use manufacturer ratings for the actual cable, pulling eye/grip, rope, puller and anchors. Blank optional limits are ignored.
References
Installation References
IEEE 1185-2019IEEE Recommended Practice for Cable Installation in Generating Stations and Industrial Facilities. IEEE lists 1185-2019 as the approved standard in its lifecycle.https://standards.ieee.org/ieee/1185/7104/
Southwire Power Cable Installation GuideEngineering guide containing route pulling-tension equations, weight correction factors, conductor stress guidance and sidewall pressure methodology.https://www.southwire.com/medias/PowerCableInstallGuidepdf.pdf
Southwire Cable Pulling CalculatorCurrent manufacturer calculator reference for conduit fill, pulling tension, sidewall pressure and jam probability.https://www.southwire.com/calculators