mohamed.elsabagh
Full Member level 2
I tried to ask this question for long time but I didn't get a real answer, should I connect my digital ground to the common earth or not?? (third wire from the power socket)
no..... not safe....... main reason
i think ground is meant for dc while earth meant for ac....
correct me if i am wrong.
The third connection on the power plug is defined as the protective ground, which is connected only with the case. AC current should flow only thorough the P to N line. In case there is a failure and current flowing from P or N line to the protective ground(e.g. due to an isolation problem or a short) the central power distribution box (e.g. in a house or factory) is detecting this failure current (typically 50mA or less) and disconnect the power line. Thus the protective ground is making sure that there is not dangerous AC voltage on case parts human can touch and cause death or massive damage to the user. The protective ground is only once connected to an earth grounding. Thus a DC power distribution should not connect the protective ground to DC ground. If the third line is defined as a normal ground then it can be connected. The best is to check with the utility how the third line is used/defined.
Nothing at all but someone told me it would be safer for the component, he also told me that the microcontroller could hang if I didn't connect the earth and the ground, I though he was wrong because of the above reasons but I didn't find anything useful on the internet, but I am more convinced to disconnect the earth and the ground now.I think the main question is : What is the project requirement that convinced you to connect them ?
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mohamed,
I agree with you on that conclusion.
However, he could be talking about some particular circuit topology in wich this statement could be true.
Could provide the schematic diagram in that you are working, to eliminate some remaining doubt ?
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I tried to ask this question for long time but I didn't get a real answer, should I connect my digital ground to the common earth or not?? (third wire from the power socket)
There is widespread misunderstanding of the the word "ground".
The meaning of "earthing" should be obvious from the word itself.
"Grounding" however, is a different matter entirely. What it means is usually dictated by what the user thinks it means, and this is often wrong, not say dangerous.
For now, take "grounding" to mean a common connection for all parts or sections of a circuit, usually the common, or 0V, of the power supply/supplies.
Analogue and digital parts of a circuit will often have separate "ground" connections which are ultimately connected together at one point.
In mains operated equipment it is usual, unless it is double insulated, to have the circuit ground connected to the earth pin of the supply. This may be to prevent mains hum in the case of audio equipment.
If your equipment is not double insulated it would be prudent to make that connection too. One option, which is provided my some manufacturers, is to provide an external link which may be connected or disconnected at the discretion of the user.
The main problem here do I need to connect the earth to the ground (which is the ground of the DC voltage regulator, and the ground of all digital modules including the microcontroller). I think I don't have to connect this connection, no I think it's not wise to do that am I right?
It is impossible to hypothesise about the cause or results of a spark.
However, so long as the case, or anything conductive mounted on the case, is connected to earth, then there is no necessity to connect the circuit's ground/s to it.
But it is usual to do so. The choice is yours.
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