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Some GS308EP switches do not comply with IEEE 802.3 Ethernet specifications
IEEE 802.3 Ethernet specifications require that the switches provide galvanic isolation between all ports and chassis ground.
this means that the POE supply is meant to be "floating" not connected to earth ground.
I have found several of these switches in my installations that do not comply with this standard. I have also found those of the same model which do comply. It seems that the newer ones do not comply. Is there some rhyme or reason for this selective non-compliance? Can I select switches which do comply by the serial numbers? surely this is not a configuration, but correct me if I am wrong.
Does Netgear offer any switches which do comply with IEEE poe requirements?
test setup:
plug switch into POE powered device, use a multimeter to check the volts to ground of the powered to device to the earth ground of the building. If you find that earth ground is mV from the powered device ground in voltage, this switch is compliant. if you find that ground is -54V from the ground on the powered device, then the PSE is non-compliant because it is providing a voltage source REFERENCED TO EARTH GROUND.
Don't believe me about galvanic isolation being a requirment?
ref: https://www.analog.com/en/resources/technical-articles/jumpstarting-ieee-802-3bts-poe.html
Hello all,
First of all, I'd like to thank everyone for their assistance.
My grounding issue is not due to any fault of the netgear switch. A cheap non-poe device plugged into a different port of the switch in my case ties the power pairs to earth ground of the building causing headaches.
I am a little sad that the non-poe powered ports' potential is able to influence POE ports but I have no clue if this particular issue is covered in the 802.3 standards.
9 Replies
Hello all,
First of all, I'd like to thank everyone for their assistance.
My grounding issue is not due to any fault of the netgear switch. A cheap non-poe device plugged into a different port of the switch in my case ties the power pairs to earth ground of the building causing headaches.
I am a little sad that the non-poe powered ports' potential is able to influence POE ports but I have no clue if this particular issue is covered in the 802.3 standards.
My grounding issue is not due to any fault of the netgear switch. A cheap non-poe device plugged into a different port of the switch in my case ties the power pairs to earth ground of the building causing headaches.
Thanks for following up.
The article you reference, relates to POE++ (802.3bt) however the switch you are testing is not a 802.3bt switch - it is only POE+ 802.3at. Can you confirm another Netgear switch you tested that provides a different result from your test?
The article you reference, relates to POE++ (802.3bt) however the switch you are testing is not a 802.3bt switch - it is only POE+ 802.3at
Block schematic does essentially not differ between ++ and +
Block schematic does essentially not differ between ++ and +
The way I understand this is that
- the power delivery itself is isolated (per both 802.3at and 802.3bt)
- if you are using shielded ethernet cable, the cable shield should be connected to earth ground at the switch (the power source).
So I think jduzan's test is best made with unshielded cable, unless it is clear how the shield is wired at the PD device.
Have thought about the problem might be caused on the PD end?
Does the issue move along with moving the PD to another port?
What make and models of PD are we facing here?
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