Cable Pulling Calculation Example From Brugg Cables

Published 11 Jun 2021

Cable pulling example from Brugg Cables Manual in Cableizer

Cable Pulling

In Part 1 of this Blog series we look at how Cableizer cable pulling calculation module has been much improved – today, we present you the application of the module in conjunction with Brugg Cables installation manual.

The following Cable Pulling Calculation example from Brugg Cables is an extract from their public document titled ‘Manual for Transportation and Cable Laying Maintenance’, published 2016. The calculation example is found on pages 12ff.

Cable Pulling

This example validates our cable pulling module and has been added to our test cases, ensuring that cable pulling calculations won’t unexpectedly and unnoticeably change.

Cable selection

In the Cable Tab of the cable pulling module the cable is selected, which in the example is of type XKDT 1×240/35 mm2, 20/12kV. Cableizer does display all relevant cable properties, which closely correspond to the values in the Brugg Cables manual (Cable weight m_tot per m of 3.36 kg, cable diameter D_e of 41 mm, minimum bending radius r_mbp of 615 mm, permissible pull force F_ppc of 9600 N).

Please be aware that Cableizer outputs all forces in [daN] (10 N = 1 daN). In addition it is shown if the cable is a single-core or a multi-core cable, and whether or not it is armoured (for armoured cables, it is possible to select pull on the armour in the cable editor as an alternative to pull on the conductor).

Selected Cables

Once the cable has been selected, it is time to select the number of cables that are pulled in together, which in this case is 3. Brugg Cables does not mention whether or not the cables are bound together (Triplex), but from their admissible pull force which is 28800 N and thus thrice the permissible pull force of a single cable, it is concluded that the cables are assumed to be bound together.

For three unbound cables the total permissible pull force is normally assumed to be only twice the permissible pull force of a single cable, as the two cables on the bottom will take all the force (the cable laying on top is not exposed to any friction). If the automatically calculated limit is not suitable, it can be manually entered (e.g. if the pull is made with woven mesh pulling grips).

The admissible sidewall pressure has been selected as 10’000 N/m in accordance with the Brugg Cables manual. Both the permissible pull force and sidewall pressure limit values are optional. However, they should not be omitted as the program will clearly indicate if those limits are exceeded along your cable route.

Cable Selector

Conduit selection

In the Conduit Tab of the cable pulling module a PE conduit with an inner diameter of 120 mm is selected in accordance with the Brugg Cables manual.

Conduit Selection

The conduit ratio CR_pull, the conduit fill CF_pull, and the conduit clearance CC_pull all show that the conduit dimensions are suitable for the intended cable pull. The conduit jamming ratio CJ_pull is not displayed since the three cables are bound together (triplex) and there is no risk for jamming.


 💡 Conduit Ratio: this is the ratio between the diameter of a single cable to the inner diameter of the duct. The conduit ratio is a measure for the cable configuration in the duct and Cableizer uses the following ratio limits:

Three cables unbound have a triangular configuration for CRpull < 2.5 and a cradled configuration for CRpull ≥ 2.5.
Three cables triplex always have a triangular configuration.

Four cables unbound have a diamond configuration for CRpull < 3.0 and a cradled configuration for CRpull ≥ 3.0.
Three cables quadruplex always have a diamond configuration.


Please notice that the conduit preview is up to scale and helps to avoid possible input errors.

Brugg Cables calculates without weight correction factor f_wc and sidewall pressure factor f_rad, and so they have not been applied to our calculation. Please consult with your supplier whether or not to apply these factors to your calculations.

Route editor

In the Routing Tab of the cable pulling module the example route is composed of sections and bends.

Please notice that the length of the cable route is slightly different between Cableizer and the Brugg Cables example due to the way the bends are handled. We have also focused on the alternative with an elevation of 20 m within the last section.

Route Editor

Our two- and three-dimensional preview help you to verify that the input is correct.

Cable Pulling

The friction coefficient μ_dyn is 0.15 all along the route (Cableizer does allow optional individual inputs for every section or bend). And since the reel is powered, there is no cable reel force.

Friction coefficient


💡 Dynamic Friction Coefficient: the coefficient of dynamic friction is a measure of the friction between a moving cable and the conduit. The coefficient of friction can have a large impact on the pulling force calculation. It can vary from 0.1 to 1.0 with lubrication and can exceed 1.0 for unlubricated pulls. Pulls should never be stopped and restarted because the coefficient of static friction will always be higher than the coefficient of dynamic friction. The coefficient of friction between a cable exterior (jacket/sheath) and conduit varies with the type of jacket or sheath, type and condition of conduit, type and amount of pulling lubricant used, cable temperature, and ambient temperature. High ambient temperatures can increase the coefficient of dynamic friction for cable having a non-metallic jacket.

Pulling lubricants must be compatible with cable components and be applied while the cable is being pulled. Pre-lubrication of the conduit is recommended by some lubricant manufacturers.


The coefficient of friction between a cable exterior (jacket/sheath) and conduit varies with the type of jacket or sheath, type and condition of conduit, type and amount of pulling lubricant used, cable temperature, and ambient temperature. High ambient temperatures can increase the coefficient of dynamic friction for cable having a nonmetallic jacket.

Pulling lubricants must be compatible with cable components and be applied while the cable is being pulled. Pre-lubrication of the conduit is recommended by some lubricant manufacturers.

The approximate results show a good agreement with the Brugg Cables manual, which states a maximum pulling force F_pull of 10’215 N and a maximum sidewall pressure F_rad of 1’858 N/m.

The difference in the sidewall bearing pressure is due to the fact that Cableizer is calculating with the inside bending radius of the conduit, while Brugg Cables is considering the radius of the centerline of the bend r_arc (which is also used as input in Cableizer).

The results also show that it is beneficial to opt for a pull in the forward directions if possible, which has both lower pulling forces and sidewall bearing pressures than a pull in the backward direction.


Cable Pulling Force & Tension: calculations of pulling forces or pulling tensions for cable trays are similar to those for pulling cable in conduit, adjusting the coefficient of friction to reflect using rollers and sheaves.

If the sheaves in the bends in cable trays are well-maintained, they will not have the multiplying effect on the force that bends in conduit have. The sheaves will turn with the cable, allowing the coefficient of friction to be assumed zero. This results in the commonly-used approximation for conduit bend equation becoming one. Even though cable tray bends produce no multiplying effect, it is essential for heavier cables to include the force required to bend the cable around the sheave. If the sheaves are not well-maintained, the bend will have a multiplying effect. The pulling force must then be calculated using the same equations used for installations in conduit.

Pulling lubricants must be compatible with cable components and be applied while the cable is being pulled. Pre-lubrication of the conduit is recommended by some lubricant manufacturers. The approximate results display only the pulling forces at the end of the respective sections, while the forward and backward direction tabs display the pulling forces all along the route. The approximate results also use a simplified equation for bends, which does not consider the gravitational forces or the vertical elevations.


Forward direction pulling forces

In the Forward Direction and Backward Direction tabs of the cable pulling module, the pull force curves and radial force curves can be calculate and displayed. As shown below, the forward pull force curve does correspond to the curve from the Brugg Cables manual.

Maximum Pulling Force

Cable Pulling Force


Special feature

Pull a cable over a longer route

It is now possible to set a cable length that is shorter than the cable route and get corresponding pull force and sidewall bearing pressure curves.

The software calculates sequentially the pull force and sidewall bearing pressure of the cable being pulled over the whole route in steps of 10 cm. This leads to rising and falling values as the cable enters and leaves bends, slopes and cable pushers. The output provides the highest pulling force and sidewall pressure the cable experiences during the pull.

This feature has been added on customer request. Please let us know if you have any proposals for improvements or clarifications.

The original article can be found on LinkedIn here

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View the other blogs in the Cable Pulling Blog Series below:


Cable Pulling & Laying Equipment

Suppliers & Distributors

Thorne & Derrick distribute the most extensive range of Low & High Voltage Cable Installation & Electrical Distribution Equipment to the Power Transmission & Distribution industry in the onshore and offshore wind, solar, rail, oil/gas, data centre, battery storage and utility sectors – this includes the most extensive range of Cable Pulling & Cable Laying Equipment to enable the installation of low, medium and high voltage power cables into underground trench or duct.

We service UK and international clients working on underground cables, overhead lines, substations and electrical construction at LV, 11kV/33kV and up to EHV transmission and distribution voltages.

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Further Reading | Handling Cable Drums & Laying Cables | A Guide from Nexans

Thorne & Derrick International distribute the most extensive range of Cable Pulling & Cable Laying Equipment to enable the installation of low, medium and high voltage power cables into underground trench or duct