Questions tagged [grounding]
Problems related to the connection of circuits to ground or earth references. Can affect safety, accuracy, reliability and interfacing.
1,277
questions
139
votes
6
answers
67k
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 ...
- 1,763
83
votes
12
answers
42k
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 ...
- 1,392
62
votes
10
answers
77k
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 - ...
- 1,630
58
votes
10
answers
54k
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 ...
- 597
56
votes
2
answers
52k
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 ...
- 16.9k
40
votes
5
answers
37k
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 ...
- 3,834
40
votes
4
answers
18k
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 ...
- 3,315
35
votes
5
answers
15k
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 ...
- 503
31
votes
6
answers
14k
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 to ...
- 915
25
votes
4
answers
5k
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, ...
- 331
23
votes
4
answers
24k
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 ...
- 16.9k
23
votes
5
answers
73k
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 ...
- 744
21
votes
6
answers
15k
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 ...
- 12.5k
20
votes
6
answers
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 – ...
- 617
20
votes
3
answers
6k
views
How could using an ungrounded appliance with a grounded extension cord be a fire hazard?
I came across a tweet recently:
Don’t even THINK about using a 2-prong plug in a 3-hole slot! Use
only the required number of slots in an outlet or power strip.
Below was a picture of a burned-out ...
- 923
20
votes
5
answers
12k
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:
...
- 1,470
19
votes
2
answers
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 ...
- 57.8k
19
votes
3
answers
8k
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 ...
- 1,547
19
votes
1
answer
12k
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 ...
- 1,647
18
votes
4
answers
48k
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 ...
- 3,315
17
votes
8
answers
6k
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 ...
- 173
17
votes
6
answers
3k
views
Failed radiated emissions test on USB cable - USB module hardware and firmware improvements
I posted a few days about ago how our product failed ESD testing. Well, it also failed radiated emissions testing so I thought I'd make a separate post.
The product is a 5V USB powered, non-radio, 3v3 ...
- 754
16
votes
9
answers
7k
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 ...
- 301
16
votes
4
answers
5k
views
Is ground connection in home electrical system really necessary?
I know that the answer to my question is "Yes, it is!". The ground connection is needed to avoid a person touching a metallic part of faulty equipment to be electrically shocked. So the ...
- 179
16
votes
5
answers
5k
views
Where is an airplane's electrical ground point?
I recently had a conversation on Reddit where someone claimed that the ground reference on airplanes was their fuel tanks. This seemed a bit off to me but I know nothing of aircraft in general. I ...
- 161
16
votes
7
answers
121k
views
How a person standing on a floor tile and holding a live equipment can complete the circuit?
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 ...
- 337
16
votes
3
answers
9k
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 - ...
- 6,204
16
votes
2
answers
71k
views
When does and when doesn't current flow to ground?
I was thinking about when current can and can't flow to ground. I came up with that current will only flow to ground when we have at least two grounds in the circuit, since then we have a complete ...
16
votes
3
answers
23k
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 ...
- 269
15
votes
4
answers
39k
views
Is a ground/common needed for proper CAN bus communication?
Since CAN Bus is a differential signalling system, what is the significance of GND/COM signal? Can I get by without it?
I've got a very simple 2-node system that has some weird happenings going on. (...
- 1,466
15
votes
4
answers
2k
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 ...
- 251
15
votes
4
answers
4k
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 ...
- 497
15
votes
2
answers
3k
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 ...
- 211
14
votes
4
answers
21k
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 - ...
- 481
14
votes
6
answers
3k
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 ...
- 179
14
votes
1
answer
9k
views
Analog & Power Ground Planes Doubts
Working on a new board, I have to face some requirements to ensure the performance of the whole system once is manufactured.
PCB is a 4-layer one, and it has both analog and digital components. But ...
- 367
14
votes
6
answers
22k
views
Why is this laptop adapter grounded?
This adapter is clearly not capable of delivering a null, a power and a ground to the laptop because the connector only has two surfaces. The adapter itself is plastic. So why is it grounded? (Note ...
- 378
14
votes
1
answer
2k
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 ...
- 1,097
14
votes
1
answer
2k
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, ...
- 57.8k
13
votes
5
answers
59k
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 , ...
- 1,051
13
votes
3
answers
9k
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 ...
- 716
13
votes
1
answer
8k
views
USB 3.0 Hub shield connection
This is about the seemingly controversial shield to ground connection. The system is basically a body-worn intel-based computer, powered by a battery. Two USB 3.0 (or 3.1 Gen1) cables come out to a ...
- 8,539
13
votes
3
answers
3k
views
The Pin 1 Problem in Audio, Star and Mesh Ground, and Contradictory Grouding Practices in Audio and Digital Systems
I recently came across the concept of "Pin 1 Problem" known in the pro-audio electronics. It seems straightforward at first, but becomes confusing when it comes to grounding. Let me describe ...
- 7,267
12
votes
4
answers
3k
views
ESD Mat and wrist strap grounding - Ground hole not available in my country
I'm building my new lab and I'm not sure where to ground since I live in the Netherlands; we only have hot and neutral available, I don't see a third a hole.
I understand I should get an ESD mat and ...
- 4,370
12
votes
5
answers
7k
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 ...
user127725
12
votes
3
answers
9k
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?
user127725
12
votes
5
answers
7k
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 ...
- 12.5k
12
votes
3
answers
2k
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 ...
- 829
12
votes
1
answer
3k
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 ...
- 3,598
12
votes
1
answer
5k
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 ...
- 7,297