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What does Ground (GND) mean?

ZeusMC

Member
Happy New Year.
Hi ,
I asked about the meaning, definition of ground. I received the following reply,
Can anyone help me to more fully understand this idea of ground, in various practical circuits, and if in schematics, then explained in these too?
Thanks, stay safe.


Hi,
Happy New year:) I’m very new to electronics,
Just read this, https://www.techopedia.com/definition/11566/ground-gnd

” What does Ground (GND) mean?
Ground, in the context of electronics, is the reference point for all signals or a common path in an electrical circuit where all of the voltages can be measured from. This is also called the common drain since the voltage measurement along it is zero.

Ground means something entirely different for electronic circuits. It is considered as the common reference point to measure voltage against any point of the circuit and is considered to have zero voltage. It is also the common connection that all electrical components must connect to in one way or another in order to complete the circuit. ”

You say GND is the connection to the – V supply ie 15-V. How can I measure voltage if is already -15V? I’m confused, could you clarify make clearer please?

I received this reply, "

admin says
January 4, 2021



If you have a dual supply with +15V, 0V, and -15V, then GND would be 0V not -15V.
But if you have for example a battery with plus and minus, then ground would usually be the minus. Note that the minus connection of a 9V battery is NOT -9V, it’s 0V.
 

Pommie

Well-Known Member
Most Helpful Member
The convention is Ground is zero volts or the voltage of the globe (ground). In reality, it's what you decide it is, it's a datum from which to measure other voltages.

Mike.
Edit, in your example of a ± supply, the supply could be 30V with a generated "ground" line. Or if no generated "ground" then it's 0V or what would be -15V if the "Ground" was generated.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
Ground has lost a lot of meaning that it used to have. In a house in the US, we can define ground. It's where neutral and the green wire get bonded to earth (like dirt);

It's also the reference for your metal pipes, metal washer, stove etc.

It's a reference most of the time, but it's a place where fault currents go as well.

A ground fault is an unintentional path to ground like through a person.
 

DerStrom8

Super Moderator
A voltage is a difference in potential between two points. "Ground" is simply the first test point, i.e. the voltage you're comparing the second point to. If you put both of your probes on "Ground", the difference in potential is zero, so this means that "Ground" is 0 volts. If you then put your positive probe on another point that has a higher potential than "Ground", you will measure a positive voltage. If you put your positive probe on yet another point that is at a lower potential than "Ground", you will measure a negative voltage. Note that your negative lead is connected to "Ground" for all of these measurements because "Ground" is your reference point, or the potential you're comparing the other points to.
 

ZeusMC

Member
A voltage is a difference in potential between two points. "Ground" is simply the first test point, i.e. the voltage you're comparing the second point to. If you put both of your probes on "Ground", the difference in potential is zero, so this means that "Ground" is 0 volts. If you then put your positive probe on another point that has a higher potential than "Ground", you will measure a positive voltage. If you put your positive probe on yet another point that is at a lower potential than "Ground", you will measure a negative voltage. Note that your negative lead is connected to "Ground" for all of these measurements because "Ground" is your reference point, or the potential you're comparing the other points to.
OK thanks, that explains the concept, in a slightly different way, to what I've already read, makes a bit more clearer to me.
 

ZeusMC

Member
Are there any other resources, vids etc I could check out, to get more understanding, of this concept of GND?
Cheers.
 

MacIntoshCZ

Active Member
Are there any other resources, vids etc I could check out, to get more understanding, of this concept of GND?
Cheers.
its just reference point when measuring voltages with yours multimeter. You can make your own ground everywhere in your circuitry and call it virtual ground. Then when measuring,black probe of multimeter will be at this point (called COM).
 

Pommie

Well-Known Member
Most Helpful Member
its just reference point when measuring voltages with yours multimeter. You can make your own ground everywhere in your circuitry and call it virtual ground. Then when measuring,black probe of multimeter will be at this point (called COM).
And, that's been explained multiple times above but the OP is asking for more, not just the same as you supplied. Suspect troll.

Mike.
 

Externet

Well-Known Member
Hello Max.
In your attachment above page 1 figure; what happens to the creatures, worms, insects, organisms living underGND in the paths of electrical current ?
Do they survive ?
 

MaxHeadRoom78

Well-Known Member
Most Helpful Member
In your attachment above page 1 figure; what happens to the creatures, worms, insects, organisms living underGND in the paths of electrical current ?
Do they survive ?
I know electric eels love it! :cool:
They become Re-Charged!
 

MacIntoshCZ

Active Member
If someone is currious then:
Leaves falling on the ground

spam spotted
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
When designing circuits, it's customary to separate the commons by "quality". and then tie them together at one point. ideally, every common should terminate in a "Star", but that's impractical.

One simple concept is:
Analog ground - This is basically a clean ground
A high current ground
DIgital
ground - An inherently noisy Ground
Earth - Exactly what it is.

These might all get connected at a single point. many times, it's a point inside the device and one elsewhere via the power cord ground pin.
If the potentials aren't huge one way you can read voltage values with a pseudo-differential A/D converter and supply stpoints with a current source. A resistor is placed at the receiving end.

A common problem that arises is a concept called "ground loops" This is where different ground potentials are connected together.

To eliminate loops in a house, sub-panels separate L,1, L2, G and N. They are connected to the main panel where G and N are joined.

Daisy chained electrical outlets will raise the ground potential between devices when a fault occurs. Lightning raises the potential of the Earth, but everything in the structure SHOULD still see the same reference, I know of an instance where it didn't happen.
 
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