There is an extra plastic or wrapper piece at the end of the electrical cables. I asked one of my friends about it and he said its for insulation purposes but he does not know the technical name of it. Can anyone kindly help me with what the technical name of this is?
See the photo to be more clear
enter image description here

  • \$\begingroup\$ strain relief grommet \$\endgroup\$ – JIm Dearden Sep 13 '17 at 13:01

It is a cable "strain relief*.

These are designed to prevent the cable bending sharply where it enters the appliance otherwise the cores are likely to fracture internally or the insulation crack.

enter image description here

Figure 1. A progressive strain relief

The progressive strain relief gets thicker and more resistant to flexing the closer it gets to the point of entry into the appliance. Even with a strong pull on the cable the radius of bending at the point of entry to the appliance can be kept reasonably large while the weak end pulls almost in line with the direction of the pull.

Note also that in your photo a hanger has been incorporated into the strain relief. This provides a means of hanging the tool securely other than hanging by the cable. The cable is typically not designed for carrying mechanical loads.

Edit: as pointed out in the comments below and clearly visible on close examination of the photo (when not bleary eyed), that's a chuck key holder. It does, however, make a good place to hang the drill!

  • \$\begingroup\$ They are often found in the cable gland category. \$\endgroup\$ – Jeroen3 Sep 13 '17 at 9:59
  • 1
    \$\begingroup\$ "Note also that in your photo a hanger has been incorporated into the strain relief" Is it a hanger, or is it for holding the chuck-key? \$\endgroup\$ – TripeHound Sep 13 '17 at 10:14
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    \$\begingroup\$ It's a chuck key hanger. :] \$\endgroup\$ – Dampmaskin Sep 13 '17 at 10:15
  • \$\begingroup\$ You're both correct. I'm six hours out of my normal time zone and wide awake four hours early. More sleep required. Fixing now. \$\endgroup\$ – Transistor Sep 13 '17 at 10:31
  • \$\begingroup\$ Although the part may have a strain relief integrated it may also just be a pure bend protection and the actual strain relief is inside the tools casing (squeeze hold by two screws). If the stain relief is opened the cable than can be pushed/pulled quite easily through the bend protection. \$\endgroup\$ – Curd Sep 13 '17 at 11:10

Strain relief.

It's not really for extra insulation so much as to protect the cable by resisting bending where it could be stressed. That could lead to fractures in the wires.

Sometimes the part itself is called a "boot" because of its resemblance to rubber boots.


Its purpose is mechanical protection to avoid damaging the cable by bending too tight.

I think the English term for that is just "bend protection" or "anti-kink".

(It also contains a rubber lobe with a hole to hold the spanner when not in use)


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