# Motion Detector Switch: What's the deal with the bare metal ground wire? **URL:** \ **Category:** Factual Questions\ **Created:** [May 2, 2017, 3:12pm UTC](https://boards.straightdope.com/t/motion-detector-switch-whats-the-deal-with-the-bare-metal-ground-wire/785717 "2017-05-02T15:12:32Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [May 3, 2017, 2:34pm UTC](https://boards.straightdope.com/t/motion-detector-switch-whats-the-deal-with-the-bare-metal-ground-wire/785717/21 "2017-05-03T14:34:32Z")
Is this perhaps a matter of designing the switch for sales all over the world? So it complies with US, British, Chinese, Japanese, and German electrical codes. Each of which has slightly different and sorta-conflicting details? IOW it’s cheaper to install the two different sorts of ground wires required by different electrical codes than it is to design and build two slightly different switches with different part numbers, different production lines, different distribution channels, etc. I’m speculating here, but we do see things like this with other aspects of electrical equipment. ---
**Author:** ![K2500](https://avatars.discourse-cdn.com/v4/letter/k/f6c823/32.png) [@K2500](https://boards.straightdope.com/u/K2500)\ **Post date:** [May 3, 2017, 4:10pm UTC](https://boards.straightdope.com/t/motion-detector-switch-whats-the-deal-with-the-bare-metal-ground-wire/785717/22 "2017-05-03T16:10:21Z")
> [@arseNal](#): > > No, it is plastic, if you are referring to the part of the switch I think you mean. Look at the pictures in the first link in my OP, you can see the white part that takes the screw for mounting into the box in the wall, that’s all plastic (top and bottom). And that’s what the bare metal wire is attached to. I guess I did read it right then. Very odd. Perhaps LSLguy is onto something then. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [May 3, 2017, 4:18pm UTC](https://boards.straightdope.com/t/motion-detector-switch-whats-the-deal-with-the-bare-metal-ground-wire/785717/23 "2017-05-03T16:18:36Z")
> [@arseNal](#): > > No, it is plastic, if you are referring to the part of the switch I think you mean. Look at the pictures in the first link in my OP, you can see the white part that takes the screw for mounting into the box in the wall, that’s all plastic (top and bottom). And that’s what the bare metal wire is attached to. OH. Look at the picture. This is for grounding a METAL WALL PLATE. That’s why. Most wall plates are plastic, but this is for the case where someone uses a metal one. Look at the little bit of wire sticking forward - it’s to come into contact with a metal wall plate. ---
**Author:** ![arseNal](https://avatars.discourse-cdn.com/v4/letter/a/ecae2f/32.png) [@arseNal](https://boards.straightdope.com/u/arseNal)\ **Post date:** [May 3, 2017, 5:05pm UTC](https://boards.straightdope.com/t/motion-detector-switch-whats-the-deal-with-the-bare-metal-ground-wire/785717/24 "2017-05-03T17:05:03Z")
> [@SamuelA](#): > > OH. Look at the picture. This is for grounding a METAL WALL PLATE. That’s why. Most wall plates are plastic, but this is for the case where someone uses a metal one. Look at the little bit of wire sticking forward - it’s to come into contact with a metal wall plate. Yeah, I think you’ve got it. Since this switch is plastic where it contacts the electrical box and faceplate, any metal faceplate wouldn’t get automatically grounded as in the case with a normal switch or outlet where the mounting tabs are metal and connected to the device’s ground internally. Thanks! And thanks for (most) everyone else’s replies as well. ---
**Author:** ![K2500](https://avatars.discourse-cdn.com/v4/letter/k/f6c823/32.png) [@K2500](https://boards.straightdope.com/u/K2500)\ **Post date:** [May 3, 2017, 8:54pm UTC](https://boards.straightdope.com/t/motion-detector-switch-whats-the-deal-with-the-bare-metal-ground-wire/785717/25 "2017-05-03T20:54:51Z")
> [@SamuelA](#): > > OH. Look at the picture. This is for grounding a METAL WALL PLATE. That’s why. Most wall plates are plastic, but this is for the case where someone uses a metal one. Look at the little bit of wire sticking forward - it’s to come into contact with a metal wall plate. AH HA! Never would have considered it. ---
**Author:** ![rbroome](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@rbroome](https://boards.straightdope.com/u/rbroome)\ **Post date:** [May 4, 2017, 6:01pm UTC](https://boards.straightdope.com/t/motion-detector-switch-whats-the-deal-with-the-bare-metal-ground-wire/785717/26 "2017-05-04T18:01:10Z")
> [@SamuelA](#): > > OH. Look at the picture. This is for grounding a METAL WALL PLATE. That’s why. Most wall plates are plastic, but this is for the case where someone uses a metal one. Look at the little bit of wire sticking forward - it’s to come into contact with a metal wall plate. Ah! good catch. I believe you have it. It is there for the times when the metal box isn’t itself grounded. I haven’t seen this on any switches I have installed, but it makes good sense. I wonder what country’s code required this? [Previous page](https://boards.straightdope.com/t/motion-detector-switch-whats-the-deal-with-the-bare-metal-ground-wire/785717.md?page=1)