Questions tagged [grounding]

Problems related to the connection of circuits to ground or earth references. Can affect safety, accuracy, reliability and interfacing.

100
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6answers
42k views

Should chassis ground be attached to digital ground?

I'm working on a PCB that has shielded RJ45 (ethernet), RS232, and USB connectors, and is powered by a 12V AC/DC brick power adapter (I do the 5V and 3.3V step down on board). The entire design is ...
58
votes
9answers
31k views

Why on earth are o-scopes earth referenced?

Thinking about it: You would never find a "Grounded" multimeter as robust and useful if a path to ground through the multimeter were introduced, modifying the circuit's behaviour and possibly damaging ...
45
votes
10answers
21k views

Why is main's neutral tied to earth?

My dad is an Electrician and I myself am an Electronics Design Engineer, and to this day he still hasn't been able to give me a good reason for this. Consider the two following pictures/situations - ...
41
votes
10answers
24k views

Why is an Ethernet cable not grounded?

There is no dedicated GND in the classical Ethernet 8P8C ("RJ45") pinout.[1] Why does the Ethernet spec not include a ground, unlike many other cable types used for interconnecting devices that may ...
38
votes
2answers
30k views

Competing PCB Crystal layout recommendations

This is related to this question: How's my crystal oscillator layout? I'm trying to layout a 12MHz crystal for a micro controller. I've been reading through several recommendations specifically for ...
32
votes
5answers
20k views

Why don't we use neutral wire for to ground devices and earth wire for closing the circuit?

I know that the neutral point of a distribution transformer is connected to the grounding (earthing) wire, so I think they are the same. Can I use the neutral wire for protecting metal-cased electric ...
31
votes
4answers
11k views

Reason of multiple GND and VCC on an IC

What is the reason that most of ICs (e.g. MCU) has multiple (A/D)GND and (A)VCC pins? If it is to increase performance of an IC, how does it help to performance? or is it easier for the IC designer ...
29
votes
6answers
12k views

Noise reduction strategies in electrophysiology

When recording electrical signals from cells (in a dish or inside a living human or animal body), one major problem is to increase the signal to noise ratio. These signals are usually in the 10uV ...
27
votes
5answers
6k views

Is it a bad idea to plug the other end of ESD strap to wall ground?

I have gone through this answer on Superuser, while it provides good information, I still have a specific question from electrical/electronics engineering point of view. Is it wrong and unsafe to ...
23
votes
4answers
4k views

Why the arc when bonding-on during high voltage repairs?

When working on high voltage power-lines via helicopter the technician will "bond-on" with a steel wand called a hot-stick. During this process an arc is conducted from the line to the wand. Now, ...
20
votes
4answers
19k views

When to use ground plane cutouts?

I've been reading more about proper grounding techniques and using ground planes. From what I've read, ground planes provide a large capacitance with adjacent layers, faster heat dissipation, and ...
19
votes
5answers
5k views

Isn't my ground different from the factory's ground?

My understanding is that ESD safety things (mats, wrist straps, specially marked soldering irons) are designed to bring everything that can touch a component to the same electrical potential energy – ...
19
votes
3answers
3k views

How could using an ungrounded appliance with a grounded extension cord be a fire hazard?

My local fire department, @Barrie_Fire, recently tweeted (then subsequently deleted) this: Don’t even THINK about using a 2-prong plug in a 3-hole slot! Use only the required number of slots in ...
19
votes
2answers
2k views

Why does connecting a high-current device to my digital circuit cause weird behavior?

I have a arduino microcontroller other digital thing and when I connect a motor pump heater other high current thing I experience weird ADC measurements reboots crashes errors in digital ...
19
votes
3answers
4k views

Static shocks all over the building

I just came from the local library, it’s quite big, and most of it is made of an architectural design using mostly painted metal book shelves painted with some kind of anticorrosive paint along with ...
18
votes
6answers
11k views

How does earthing work when earth is dry?

Earthing is meant to provide reliable contact of an electric appliance to earth so that if there's an insulation fault current goes into earth instead of through a person's body. This requires ...
17
votes
1answer
10k views

With shielded twisted pair cable, do you ground one end, both ends, or neither ends of the shield

I've got a project coming up that's to be doing RS-485 communications over shielded twisted pair cable. The project will involve cable length runs of many 10s of ft and the cables will probably have ...
15
votes
9answers
5k views

Grounding in space

I'm working on a project that will be launched inside a Blue Origin New Shepard rocket and need to know the details of how our experiment will be grounded. The experiment will have a 5 V USB 3.0 ...
15
votes
8answers
5k views

What is the right way to float a home lab?

I just got myself some new toys for my lab at home like 30V DC power supply, KKmoon signal generator and a Rigol DS1052E. I want to float everything, because I don't want to spend any money on stuff ...
15
votes
3answers
6k views

Why is there a 0R resistor linking GND and AGND in analog voltage reference circuit?

This is related to another question I've just posted (What's the purpose of a ferrite bead inductor on this circuit?), regarding the battery charger described in the AVR450 Application Note - ...
15
votes
2answers
2k views

Grounding PCB to enclosure

I am designing a small sensor which fits into a custom aluminum enclosure. The sensor uses CAN bus and a long cable to connect it to the host and power. The shield of the cable will ground the ...
14
votes
7answers
107k views

How grounding works to prevent electrical shock

Can someone please explain the how grounding / earthing to prevent a person from getting electrical shock using simple illustration of a faulty electric iron connected to the 240VAC mains? I don't ...
14
votes
3answers
919 views

Why an electrician wiring error could make a PC's USB shield be at 120V when it should be grounded

I almost had a serious electrical accident last week when I was trying to use an oscilloscope to test out a circuit a student had built. I had the scope plugged into a floor outlet, and the circuit ...
14
votes
1answer
1k views

Should the unused areas on the top layer of my RF PCB have ground pours?

I realize there are some questions that are related to this topic but I didn't see any that are really RF specific. I am working on a 2-layer Bluetooth module and I have some unused spaces on the top ...
13
votes
6answers
2k views

How to stop plastic granules sticking to the iron wall of their silo?

In our factory, we have some large (8 meters tall and 3 meters in diameters) iron silos for storing the plastic compounding material. Every time the silos are getting unloaded from the granules, the ...
13
votes
3answers
18k views

Grounding and why charge leakage occurs

A basic nugget of info is missing in my end-to-end picture of how grounding works and why it's important. When a voltage is applied in a circuit the electric current starts flowing (or the field ...
13
votes
6answers
48k views

How to safely ground a switching power supply with floating outputs?

I just received a 120VAC to 5VDC (20A) switching power supply (the kind with a passively ventilated metal casing) for use with a microcontroller project I'm working on (driving long LED strips). I've ...
13
votes
3answers
2k views

How can I ensure low-resistance ground contacts to an aluminum enclosure?

I am building an electronics project with an aluminum enclosure. I need to ground it—and very well—for human safety. (The system handles 300 A of current, and I want to be sure that if there is an ...
13
votes
1answer
1k views

Is it possible to reject noise traveling on the outside of a coaxial transmission line?

Say I have some ordinary coax between a receiver and an antenna. That coax will have three currents in it: the desired signal an exactly equal an opposite current on the inside of the shield (really, ...
12
votes
5answers
53k views

Why should a circuit be grounded?

Why should a transistor circuit be grounded? The way I understand it is that ground is an infinite supply of electrons and so it is equivalent to the negative terminal of a battery. But in this page , ...
12
votes
4answers
16k views

Where is the ground/negative for overhead power lines?

I recently learnt that ground can be used to complete circuits using high voltages. I'd like to know if this is how overhead powerlines work, and if so where exactly do the cables/circuit terminate - ...
12
votes
4answers
22k views

How should I connect AGND and DGND

I have been reading about grounding in a mixed signal systems. Do I get it correct that it is best to group analog and digital elements and then have a single ground plane, as long as the digital ...
12
votes
4answers
6k views

Why would a power supply unit with insulating case and galvanic separation need a grounded power cord?

Recently I witnessed an external IBM laptor power supply that looked like a usual switched-mode power brick (rather small and lightweight for it more than 50 watts power) in plastic case but had a ...
12
votes
3answers
5k views

Coaxial cable signal and ground

How does a coaxial cable carry RF, audio and low freq. signals? I understand there must be a difference between all these, for example the return path being through the shield or not. Can someone ...
12
votes
4answers
3k views

RS485 network ground pin - when to connect?

As many know, one can implement a simple node to node rs485 communication by using only two wires, A and B. Well, the standard specify to connect the ground of the two node together. from Wikipedia: ...
11
votes
5answers
4k views

Anti-static mat connected to earth directly or 1E6 ohm resistor?

Should an anti-static mat be connected to earth directly or with 1E6 ohm resistance in between? 2 layer mat. Upper side: dissipative (10E7 ~ 10E10 ohm/m²). Bottom: conductive. To be a little more ...
11
votes
5answers
4k views

Automotive ground shift phenomenon

I'm working on the integration of a sensor into an automotive platform, using a standard 12v negative chassis setup. I am trying to understand a somewhat mythical phenomenon that is experienced known ...
11
votes
3answers
1k views

What is mecca ground?

I came across few different ground names (digital, analog, signal, power, mecca, EM, shield, etc). I do understand most of them - but mecca is a new one for me. Can someone please explain this mecca ...
11
votes
2answers
4k views

Why are some mounting holes connected to ground?

Why are plated mounting holes connected to ground ? I read that if you are connecting your board to chassis ground, then it should be connected at only one point and connecting say 4 mounting holes ...
11
votes
1answer
4k views

PCB 'Emi proof' design

Currently I'm designing a GPS basestation which will have a radiomodem (broadcasting at 407-480MHz), a ARM7 microcontroller running at 60MHz and a FTDI USB chip. The FTDI USB chip even runs at 480MHz ...
10
votes
3answers
5k views

Anti-static wrist strap around your wrist or around your ankle?

Does it matter whether you wear your anti-static wrist strap around your wrist or around your ankle?
10
votes
4answers
6k views

Why we use ground

I have been wondering this for a while, so I did some digging, and as usual, wikipedia was the most illuminative. It looks like the telegraph was the first time ground was introduced to complete a ...
10
votes
3answers
1k views

What do I do with the extra “ground chassis” tab on a DC power jack?

Product Link Datasheet I have about fifteen 9v wall warts within specs for the circuit; I'm going to use the one that fits the jack. There are three solder tabs on the jack. One for the positive tip,...
10
votes
1answer
2k views

Why is this resistor connected between connector shield and ground?

I was looking over my raspberry pi model B and I noticed a resistor between the USB power connector shield and ground. I've noticed this on many PCB designs with much larger packaged resistors ...
10
votes
1answer
657 views

how much is it safe to common-ground power supplies?

Some circuits requires more than 1 power source for voltage comparison or whatever reason and the circuit requires that the power sources shared the common ground. Most of the time it works perfectly ...
10
votes
2answers
2k views

Grounding of ADC grounds

Fast, high resolution ADCs, especially ones that have parallel output, usually have a separate supply pin (DRVDD, (drive vdd) or OVDD (output vdd)) presumably because they don't want to couple noise ...
9
votes
2answers
5k views

Recommended way to connect the exposed pad to ground pins

Is it okay to connect the exposed pad to the ground pins as in the image below, or is there a recommended way to do it?
9
votes
2answers
15k views

How to check if something is mains earth grounded?

Suppose I would like to verify that the ground terminal on an indoor power outlet is actually connected to the ground (from what I've read, some of them aren't!). How would I go about checking that? ...
8
votes
2answers
4k views

Grounding Metal Object to Eliminate Static Electricity Using Electrical Ground

let us say that I have built a metal cabinet in which I will be painting small objects. I am looking to eliminate any static electricity that could possibly build on the object to be painted or on the ...
8
votes
1answer
1k views

How is the following ground symbol different from conventional ground?

I've seen the following ground symbol in quite a few schematics: How is this different from the typical GND symbol?