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I have an NVR that has a power brick and a separate ground screw. What is the "Right way" (read: safest way) to connect this to ground? I've thought of a couple ways to do it.

Ground Screw

My 4 options are:

  1. Leave it unconnected. This seems like a bad idea, since several cameras are outside and I want to have at least some protection against ESD.

  2. "Run a line" off the outlet. Either splice in an extra wire that sticks out of the outlet cover (Seems like a terrible idea), use the screw in the center of the outlet, or get some sort of special outlet with an extra screw.

Run a line off the outlet

  1. Use an ESD plug

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  1. Use some sort of ground only plug.

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    It was my understanding that these grounding lugs were so that equipment that shares analog signals can be grounded together, not necessarily to tie the box to the electrical system's ground. I mean, if they wanted the box to be grounded, it would just have a three-prong plug, right? Not an answer, because I could be wrong. – JPhi1618 Apr 4 '18 at 17:59
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    Is the power brick marked with a "square within square" symbol? – ThreePhaseEel Apr 4 '18 at 22:39
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    Grounding is not ever to be used as a signal path. In fact, ground loops can cause crazy things to happen. The whole purpose is to make sure nobody gets a tingle or even a full-on shock from touching the case... For devices that run on wall-wart power supplies they are usually not necessary. – SDsolar Apr 5 '18 at 0:29
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    So are you an evil connoisseur of chicken fingers? – JPhi1618 Apr 5 '18 at 0:50
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    @DarthCaniac, the symbol means that it is double insulated and does not require a connection to earth/ground. – JPhi1618 Apr 5 '18 at 17:16
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Grounding of metal cased equipment is most often done for safety reasons, rather than ESD protection. If a fault occurs inside the equipment that places line voltage on the chassis, the voltage is shunted to ground and will trip the breaker on the circuit. This protects you from accidental electrocution.

Edit: Since this is powered by a brick, safety grounding is unlikely. For ESD protection, the wire can simply be connected to any suitable earth ground. I would suggest whatever method you find most esthetically pleasing.

  • Possibly, but a power brick means this isn't using the full outlet voltage either. Not as much risk from an NVR using, say, 20v and 2A – Machavity Apr 4 '18 at 19:58
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    The manual (As well as various sites) say that the device should be grounded to protect the cameras from ESD – DarthCaniac Apr 4 '18 at 20:38
  • Thank Machivity, I totally missed the power brick part. I edited my answer to make it better. – Norm Apr 4 '18 at 21:46
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This is in addition to Norm's excellent answer, which is the correct answer (and I upvoted it).

ESD stands for "electrostatic discharge." It's usually used to describe protecting highly sensitive electronics (computer chips) from the kind of discharge you get walking across a carpet. That is NOT the case here.

It's odd that they're using the term "ESD" because what they're talking about is the kind of charge that would come with a lightning bolt. Yes, technically it is ESD, but nobody but we professionals would ever think of it that way. As an engineer who designs integrated circuits (chips), I'd call it "charge coupling" or simply "to protect against nearby lightning strikes," but whatever floats their boat.

A bit of detail to help you understand the problem... The passage of electricity causes a magnetic field. When that magnetic field passes through another wire, it "couples" charge onto the wire, meaning electricity flows thanks to that magnetic field. This is how electric motors work. Lightning has so much energy that even a nearby strike can couple charge onto your housewiring, phone wiring (if you still have any) or onto the wires used for your cameras. I actually had this happen when I lived in Texas. A single bolt burned out phone wires in the walls of my house and blew the data port on a printer. Pretty cool for something you can't actually feel as a human being (well, it was cool until I my wife told me I had to fix it. Geeks...)

My point is this: if your area is not prone to lightning, you can safely ignore the wire. If you experience more than a bolt near your home a year (that's a fair amount of lightning, by the way, to experience a bolt near your home annually), then you'll want the wire. It will also help to minimize the length of wire to the cameras that's exposed to the effects of lightning, meaning any excess wire should be coiled up and held with a zip-tie.

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