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If a device such as this potentiometer has a metal case, should the case be grounded or left floating? Electrically the case is not connected. Data sheet

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    \$\begingroup\$ I would ground it. But it is basically just an opinion. Floating metal is generally bad for radiated emissions, but it is not very big. It may also reduce cross-talk slightly to have it grounded. \$\endgroup\$ – mkeith Jan 19 '17 at 1:06
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    \$\begingroup\$ Gnd is better to divert ESD than signal from 2cm arcs \$\endgroup\$ – Sunnyskyguy EE75 Jan 19 '17 at 1:16
  • \$\begingroup\$ It looks like they specified a square hole for the snap-in, and did not specify pads sizes for the pins, so it is your choice if you want a PTH or not for the snap pins. It may not be necessary to gnd it if there are no stray signals running beside it. \$\endgroup\$ – Sunnyskyguy EE75 Jan 19 '17 at 1:25
  • \$\begingroup\$ Agreeing with the comments so far ... not essential but better to ground it ... can anyone think of a downside? I can't, beyond the minor difficulty of soldering a larger thermal mass (which I would recommend anyway for improved mechanical strength) \$\endgroup\$ – Brian Drummond Jan 19 '17 at 12:17
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Floating pieces of metal are mostly unwanted. The reason is that they have an high impedance to the environment and can pick up noise and then induce noise to you circuit.

By connecting it to your ground plane the noise will flow a defined path to your ground instead of some sensitive circuit nearby.

BUT: Be aware that these components usually stick out of your enclosure. An esd discharge path is also created to your ground. If you have a metal enclosure connect it directly to the enclosure and prevent the discharge going via your pcb. If esd is a high risk and you have a plastic enclosure, make sure you add proper esd suppression. Isolating this piece of metal by not connecting it to anything is almost impossible because of the pins nearby (small spark gap).

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