What does 'ground' mean when connecting a circuit?

[bmed90]

Greetings,

When connecting a circuit what does it mean when someone refers to the "ground'. Like for example, when someone says, "ok, we are connected to ground". You know? That is the sort of thing I am talking about.

 

[phinds]

There are two kinds of ground. "Circuit ground" which is just a local reference that is taken to be zero volts, and "Earth ground" which IS zero volts and is literally connected to the Earth.

 

[analogdesign]

One of the things that drives students crazy is the concept of signal ground. It literally can be any node in the circuit at all because the concept of voltage only makes sense as a measurement BETWEEN two nodes.

In practice, the "ground" node is usually always eventually connected to the chassis of the equipment you're using. Then it is connected finally to "earth ground" as phinds mentioned through the power supply.

 

[meBigGuy]

Ground just means the 0 volt point. For example, in a single positive supply system, the power supply connects between +V and ground. Everything gets current from +V and returns it through ground.

 

[Windadct]

Also - voltages are all relative - so the ground helps define "relative to what?" However grounding is its own specialty - and complex systems can have multiple grounds, for each type of circuit - confusing yes, so calling something "ground" without context (chassis, signal, DC supply, AC supply, RF - etc) - is almost meaningless - they each fundamentally mean the same thing - but how they are constructed, best practices as well as their purpose and effect on the operation of the circuit can be quite different.