I have an optical encoder with four wires: Green = A phase, white = B phase, red = Vcc positive power supply, black = V0.

Additionally, it has a metal shielding layer in the cable. Now I don't know what is the use of this metal shielding. Can anybody provide some information about it?

product image of rotary encoder

image of pigtail cable of the encoder

  • \$\begingroup\$ Connect it to the ground/earth. \$\endgroup\$ Sep 5, 2016 at 12:55

1 Answer 1


It's the shield. Usually you should connect it to the ground (instrumentation side).

  • \$\begingroup\$ What if i leave it as it is? \$\endgroup\$
    – TIWARI
    Sep 5, 2016 at 10:58
  • 1
    \$\begingroup\$ Not a good idea.. if you want to go in deep, the web is full of resource, like this or this. \$\endgroup\$
    – Antonio
    Sep 5, 2016 at 12:07
  • \$\begingroup\$ Why downvoted? How I should improve this answer? \$\endgroup\$
    – Antonio
    Sep 5, 2016 at 13:44
  • \$\begingroup\$ I guess the downvoter would have liked if you explain why should the shielding connected. But it is just a guess. \$\endgroup\$ Sep 5, 2016 at 15:16
  • 1
    \$\begingroup\$ @TIWARI Some devices have ground as a reference (stable) potential. Disconnecting it you are making it floating (instable) reference. Other devices use ground for security. Disconnecting it you are making this security knowingly inefficient. Ground shall be the first to be connected and last to be disconnected. Keep it as eleventh commandment :) \$\endgroup\$
    – Crowley
    Sep 5, 2016 at 15:58

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