Network connecting laptop to PC and grounding issue ?!?

  • Thread starter Thread starter Skybuck Flying
  • Start date Start date
S

Skybuck Flying

Hello,

As you might now by now I am investigating grounding issue's ;)

The ammount of issue's with it is already staggering ! ;) =D

My latest question/wonderings is about laptops.

Laptops can either work without power cords/on batteries... or with power
cords even non-grounded power cords.

My first question is:

What if a battery-powered-laptop is connected to a PC via an ethernet cable
and the laptop has a small defect... for example the laptop fell onto the
ground and has slight issue's.

Or perhaps it has a small leaking current by design.

Could this cause a PC from getting damaged even if the PC is grounded ?! ;)

I would guess not because the motherboard clips on the ethernet ports are
touching the case... so perhaps any additional current/volts which might
travel via ethernet are immediatly transferred onto chasis and into ground
?!?

Or perhaps ethernet is not designed for situations like this and
volts/ampere will directly go into motherboard and damage stuff ?!?

Same question could also be asked for cable modems and such.

Bye,
Skybuck.
 
Skybuck said:
Hello,

As you might now by now I am investigating grounding issue's ;)

The ammount of issue's with it is already staggering ! ;) =D

My latest question/wonderings is about laptops.

Laptops can either work without power cords/on batteries... or with power
cords even non-grounded power cords.

My first question is:

What if a battery-powered-laptop is connected to a PC via an ethernet cable
and the laptop has a small defect... for example the laptop fell onto the
ground and has slight issue's.

Or perhaps it has a small leaking current by design.

Could this cause a PC from getting damaged even if the PC is grounded ?! ;)

I would guess not because the motherboard clips on the ethernet ports are
touching the case... so perhaps any additional current/volts which might
travel via ethernet are immediatly transferred onto chasis and into ground
?!?

Or perhaps ethernet is not designed for situations like this and
volts/ampere will directly go into motherboard and damage stuff ?!?

Same question could also be asked for cable modems and such.

Bye,
Skybuck.
Click to expand...

Ethernet is galvanically isolated. The Ethernet interface uses tiny transformers,
and the Ethernet differential pairs run through a transformer. By doing so, it
eliminates issues with potential difference between equipment ground.

http://en.wikipedia.org/wiki/Galvanic_isolation

The Ethernet transformers are housed in a plastic chip. In this schematic,
you can see the transformer package for the Ethernet, on the right hand side.

http://www.avrfreaks.net/wiki/images/EVK1100_ETHERNET_Pinout.jpg

This is what the plastic package with the transformers looks like physically.

http://www.cetus.com.cn/pic/LCZ3N1JA.jpg

A gigabit Ethernet interface, has more transformers inside the plastic
chip, than a 10/100BT interface would use.

Paul
 
Back
Top