Outlets not grounded? Remedy

grounding

For some months, I'm renting an apartment in the Canary Islands. It looks like the plugs are not grounded. For example, when I connect my laptop, a ThinkPad T420si, then I feel an unpleasant sensation on my bare legs when connected to mains (220V/50Hz). A similar sensation I get when touching certain parts, incl. plastic parts (!), of my smartphone when connected to the laptop. Contrary to what I wrote before: When connected to the USB charger, I do not get that sensation when touching the smartphone.

My guess is that the outlets are not properly grounded. While I assume there is no risk for my health, I am a bit worried about my electronic devices. Also, I may want to do some electronics soldering, and I don't like the idea of the soldering iron's tip possibly being on a different potential than ground.

What options do I have to remedy the problem? An isolating transformer?

Update as of 2014-10-15 WEST

After removing the Schuko (fype F) multiplier, and upon close inspection of the outlet, I realized that the center hole is not a screw hole. It is ground, i.e. this outlet is of type L. So I bought an adapter, and yesterday the problem was gone:

Photo of adapter type L to type F

Facepalm!

But wait, today the problem is back, and in the entire apartment! For the first time, I felt a potential when touching the washing machine in the bathroom, and this one is connected with a Schuko plug to a Schuko outlet:

Photo of washing machine plug type F in outlet of the same type

Something is wrong here. Probably unrelated: Some days ago there was a power outage, I think affecting several houses, i.e. not just the one I'm living in.

Best Answer

This is not about grounding, or perhaps it is...

Lets start with your connectors: Do you have AC-connectors at your devices with or without grounding pin? Laptop psu may have a protective earth connection, a phone charger won't have one. I've never seen a phone charger with protective earth connection.

Both PSUs are doubly insulated, I'm pretty sure, which means primary side is galvanically separated from secondary side, which includes everything which can be touched with bare hands.

How does this sensation of 50 Hz AC come over to touchable parts? There's something calle Y-Capacitor between primary and secondary side in these PSUs. It is used to provides a stable potential for the regulating circuitry of the PSU, i.e. it prevents the secondary side from "floating". It can be described by two small capacitors in series between neutral lead and live lead on primary side with the middle node connected to the ground of the secondary side. Hence, on a 230V system, the secondary side gets a level of 115 V AC. The capacitor is designed to permit a maximum current of 0,35 mA to flow, if shorted to ground. This is a current you can sense, but which cannot harm you or your equipment.

If something with earthing in your mansion was wrong, it would not change this effect in my opinion.

In the rare case, your PSUs really have a protective earth connector you should not be able to sense that voltage as it was conducted away. In this rare case you should get an electrician soon, because if you touch your oven or washing machine there is no such limiting capacitor to protect you in case of an failure.

I have a different theory why you feel somthing you do not know at home. On canary islands it is rather warm and carpets are rare while most homes have tiled floor. If you live somewhere cold the rest of the year you probably have carpets or wooden floor which reduce capacitive coupling by orders of magnitude. You just may not feel the phenomenon while it is there, too.

Update

Relating to your updates: Now you do have a problem. When you feel a tickling sensation when touching devices like a washing machine there is one possible conclusion: the potential of protective earth connected with the housing of your devices differs from the potential of your house. Which can mean different things.

  • You have only 2-wire conduits in your house. The neutral and protective earth in your wall outlets are connected to one common wire (usually blue in EU). Some connections in your house have too high ohmic resistance. When under heavy load, voltage on N and PE rises, hence you can feel the influenced voltage.
  • Protective Earth is somewhere broken, effectively. This is really bad, as all Class 1 equipment relies on working PE and a short to housing, which especially water bearing devices are prone to, will put the full voltage to touchable parts of the defective devices.
  • And if PE is interrupted at the equipotential bus bar it gets even worse. Not only a faulty potential from one defective device will propagate through your complete building and be present on every Schuko (PE contact), but will also be induced by assymetric load in the 3-phase-network between the next transformer station and your house. Which means, even if all devices in your house are depowered properly, PE-conductors may conduct harmful voltages.

For the last two options, your life is at risk. You should get an electrician to prove me wrong. The first possibility can be verified by opening a wall outlet (of course after opening the circuit breaker, securing it against reconnecting, verifying all pins in the outlet are deenergised and so on). If there are two wires only and one of them connects to N and PE you have a “bootleg ground”, which renders even ground fault interruptors partially useless.