Step-by-Step Jointing Instructions for Nexans JTS Heatshrinkable MV Cable Joints
Nexans JTS Heatshrinkable MV Cable Joints
Nexans JTS range of Heatshrinkable MV Cable Joints consists of high performance, compact and easy-to-install Straight Cable Joints with Triple Wall Tube Technology. This technology allows installers to heat only one tube instead of three for 12 to 24kV applications, and two tubes instead of three for 36 to 42kV applications. This innovative solution simplifies and shortens the installation process and minimises the risk of joint failure. In this guide, we’ll walk you through the necessary steps for preparing and jointing cable with JTS, but also give you some technical tips on the installation instructions.
DISCLAIMER: At this point, we need to highlight that the installation of the JTS range or any cable joint should be performed by competent personnel, familiar with electrical equipment and safe operating practices. Additionally, all parts of the kit should be visually inspected for possible damage and installed in accordance with the manufacturer’s instructions. This guide and following the below instructions DO NOT substitute adequate cable jointing training!
Key Features & Benefits
Nexans JTS range of innovative Heatshrinkable Medium Voltage Cable Joints bring a vast number of features and operational benefits, including:
- Quick and Easy to install saving labour time, with no additional retraining required.
- Short and Slim design with impressive range taking sizes.
- Eliminates typical jointer errors.
- Excellent Insulating Properties for safer installations.
- Advanced Screen Connection & Armour Continuity for maximum control of fault currents.
- Thick Walled Tubing for High Mechanical Strength and Impact Resistance.
- Protection against Water Penetration & Chemical Aggression.
- Stabilized UV Protection for outdoor longevity.
- Halogen Free Material for safer use in enclosed spaces.
- Made to measure Fire Resistant blankets if required.
- LSOH outer sheath as standard.
- Fits single core and three core MV cables up to 36kV.
Cable Preparation – How to prepare cable for jointing
Straighten and set cables at the joint position. Determine the centre of the joint and cut one cable to length.
Cut the other cable with a 250 mm overlap. Clean both outer sheaths for 1 metre.
Remove the outer sheath for a distance “Y” as listed below, for one cable and “Y” plus 250 mm for the other cable.
Y = 170mm for “Triple Wall” Tube Length of 300mm
Then, abrade the outer sheath on both cables for a distance of 100 mm and clean the abraded area.
Fold back the screen wires and bind temporarily with PVC tape.
DO NOT CUT THE SCREEN WIRES!
Cut the cable with the 250 mm overlap to the correct distance “Y” as listed in the table.
Remove the semiconductive layer to a distance of 50 mm from the sheath cut. Take care not to damage the insulation.
Bare the conductor for a length of inside depth of the connector for mechanical types or, in case of compression connectors, for a length of inside depth of the connector + 5 mm. Clean and degrease the conductor.
As a protection, wrap few turns of adhesive tape around the conductor end.
The cable preparation is finished. Now, slide all the heat shrinkable tubes onto the cable on one side of the joint.
Cable Jointing Instructions
Ensure you followed all 5 steps of cable preparation above and both cables are ready for jointing. Important Note: All the heat shrinkable tubes must be on one side of the joint before moving to the next step of the jointing instructions.
Install the GPH Mechanical Cable Connectors (M95-300) onto the cable cores as per the manufacturer’s instructions. If using hexagonal compression links ensure that any sharp edges and flashing are removed from the connector with a file or abrasive cloth.
Tighten and shear off the hexagonal bolts with the appropriate tool. In this example, for the outer and inner bolts, we used a SW13 battery-operated tool. You can also use a wrench or spanner.
If using mechanical connectors make sure you fill up any indents left after shearing the bolts with void-filling mastic clay.
Wrap the Dual Layer OM Stress Control Mastic Plate / Patch around the connector area. Centre the patch over the connector with equal distance at both sides. Do not squeeze the extremities. Ensure the mastic plate has bonded to itself by using the paper backing to apply mild pressure.
Apply a layer of stress-relief OM Mastic Short Strip overlapping the semiconductive layer and the insulation of the cable. Approximately 10mm onto semiconductive layer and 10mm onto core insulation. Ensure the mastic has bonded to itself by using the paper backing to apply mild pressure.
Position the GT125 Triple Layer Wall Tube in the centre of the joint, pre-heat the tube for a minute and start shrinking from the centre towards to the edges. Adjust torch to give a soft blue flame with yellow tip. To avoid over-heating of the heatshrinkable tube, keep the flame moving continuously and maintain an adequate distance from the tube (15-20 cm) with the angle of 45°.
Make circular moves around the tube to ensure a smooth and even final result, avoiding wrinkles along the surface. Continue the heatshrinking in circular sectors, while alternating on both sides. At the end of the work, the surface of the heatshrinkable tube must be smoothly wrapped around the joint.
Wrap the whole joint with a metallic tape (Copper Screen Mess), using a 30% overlap, start and end on the edge of the triple wall tube. Make a knot to lock the metallic tape.
Apply a layer of NGAF Sealing Mastic at both ends of the copper screen mesh.
Remove the PVC tape previously applied to fix the screen wires (Step 3 of Cable Preparation). Fold back the screen wires towards the centre of the junction distributing them along the joint.
Cut the screen wires at the desirable length, in order to be able to fit the screen connector in between and connect them.
Insert the Screen Connector and fix the screws, ensuring the correct torque is applied to shear off the connector bolts without damaging the screen wire. In this example we used an SW8 battery operated tool.
Apply a layer of NAE Protective PVC Tape over the screen wire connector.
Clean the abraded area of the outer sheath on both cables. Apply a layer of NGAF Water Sealing Mastic, starting 30mm from the edges of the outer sheaths and finishing at the screen wires, covering them for 50mm.
Position the GT3 Outer Protection Tube over the centre of the joint and start shrinking from the centre towards the ends.
When the joint is complete, allow to cool before moving.
Nexans Solutions & Training Centre
Nexans JTS Heatshrinkable MV Cable Joints provide a cutting-edge solution for efficient and reliable cable installations. The above step-by-step cable preparation and jointing instructions constitute an installation guide for JTS cable joints. However, it is crucial to emphasise again that the installation process should be undertaken by competent individuals well-versed in electrical equipment and safety practices. Always adhere to the manufacturer’s instructions, visually inspect components, and dispose of waste responsibly.
Nexans have several comprehensive training centres all over the world, providing competency certified training for cable joints, separable connectors, terminations and other power accessories. They also offer installers the possibility to be trained at their premises or directly at construction sites. Contact us for additional information.
Our Technical Advisory Centre can answer any questions you may have regarding this range or any other power accessories needed for your project:
email@example.com | +44 (0)1744 762 929
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