A stress cone is used when terminating a medium to high voltage cable to prevent insulation failure. Without a stress cone, the high voltage's electrical field would curl back at the termination point and melt the insulation. These devices are used for high-voltage overhead wires, industrial wiring, electric motors and wiring computer networks. Installing a stress cone requires de-energizing the device or supply wires first. This is done by turning the power off upstream.
Things You'll Need
- Non-contact voltage detector
- Metric ruler
- Utility knife
- Electric tape
- Safety solvent
- 14-gauge insulated copper wire
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Turn off the power for the wires you are working on at the main distribution panel. Confirm the power is off by touching a non-contact voltage detector to the wires' insulation. Double check the power is off by trying to activate the attached device.
Pull the end of the cable into a position to be easily worked on. Determine the required amount of exposed cable necessary to make your connection after the stress cone is installed. This is dependent on the device you are fastening it to. Consult the owner's manual for this information.
Unwrap the concentric neutral wires from the outside of the cable and pull back the length of the exposed cable, plus the length of the stress cone. The concentric neutrals are the wires wrapped around the outside of the cable. These now form the ground lead.
Determine the length of insulation that needs to be removed for your specific stress cone. This information is found in the owner's manual. Add this length to the length of the exposed cable. Cut and remove the wire semi-conductor shield this length. Be very careful not to nick or cut the insulation.
Clean the newly exposed section of the insulation with a rag soaked in safety solvent to remove the semi-conducting residue. Only wipe away from the cable.
Measure back 25 mm from the newly exposed section and wrap the wire with electrical tape. Apply the supplied lubricant to the cable insulation and the inside surface of the stress cone.
Insert the stress cone on the end of the cable by rotating and pushing it until the end of the stress cone is flush with the electrical tape.
Apply lubricant to the inside of the modules and slide them on the end of the cable by rotating them as well. Repeat this process to install each module.
Wrap the supplied grounding clamp around the stress cone and tighten with a screwdriver. Connect a 14-gauge copper wire to the clamp and run to the system grounding location.
Run the concentric neutral wires to the grounding system as well. Fasten both wires to the ground terminal.
Mark the insulation on the top of the last module by scoring it with a knife. Remove the last module then finish the cut through the insulation and remove it. Reinstall the last module on the wire.