Question AC voltage/current leakage from ethernet switch ?

[sumitsimlai]

Hello everyone on the forum.

I'm in a difficult spot with my home computer setup with LAN. Recently I had an issue that was resolved by replacing the RAM. When I connected the laptop to the network, I felt a mild electric shock. After disconnecting ac power, with the LAN cable connected, I checked with a voltage tester screwdriver on the metal body of the laptop and, lo and behold, the lamp was glowing. I didn't want to risk damaging the laptop so removed it and tried to trace the fault right up to the two main sources, i.e. the ac power supply and the internet router (extender).

I didn't find any problem with the ac source, having confirmed with a digital multimeter the L-N and L-E voltages as almost equal (1 or 2 V diff).

I then used the voltage tester screwdriver to check for live ac voltage on the metal shielding of the ethernet cable connector, and on the body of my ethernet switch (Linksys SD208, not PoE - old stuff), and the lamp glowed in both cases. Using a multimeter, I found voltage of around 65V ac (I am in India, so the house electricity supply is 240V ac) when unconnected, and 150V ac when connected. Strange!

I replaced the adaptor with a similar one from TP-Link but my observations were the same.

While I am yet to confirm the above observation, I am unable to understand how the switch which operates on a 12V dc supply, can produce 65v or 150v ac and result in current leakage?

Anyone with a background or technical experience in the above area - please help me understand so that I can pinpoint the problem and get to work.

Thanks in advance.

 

[Alfieanderson42]

It sounds like you're experiencing ground potential issues or stray voltage, possibly due to faulty grounding in your electrical system. Check your grounding, inspect cables for damage, and ensure all devices are properly grounded.

 

[bill001g]

So why are you using shielded ethernet cables. Only shielded cables have metal contacts on the plugs.

By default ethernet is magnetically isolated. Most also have optical isolators. This is done to prevent the exact problems you are having. The plastic insulators on the wires and outside of the cable prevent any current flowing.

Shielded cable provides no benefit unless it is properly installed and like in your case it can cause power/ground issues. Proper shielded cable has the shield connected to ground on both ends of the cable. Note this is a special separate grounding connection it is not the ground lead that is in a electrical outlet. You need to run a special ground wire to each end of the connection. This is not something that is really possible in a home install, you only really see it in large data centers where every rack is connected to these special ground connections.