Small Electric Current Running Through Outer Laptop Casing

[JimmyGreaves]

Another electrical question.

I have recently started to get a small electrical current running down the edges of my laptop casing (metal acer travelmate). UK plug plugged into an extension lead. Also experienced this on a DVR that has a metal case.

Any clues as to why this may be happening? I'm clueless with electrics!

[Norseman]

I guess this is due to a bad ground connection.
You have to check the wiring's and see to that the wall socket and extension cord are grounded properly.

[poosmate]

Check that the extention lead has an earth. Does the plug that you put into the wall have three pins? Many cheap extention leads have three holes bot only a two pin plug and twin core flex this type of lead should not be used for an appliance that requires an earth ( three pin ).
Another issue linked to this problem is getting shock ( tingle) from a DVD player with a metal case that was not designed to be earthed fitted with a two pin plug. This was caused by the UBC box not being grounded and the current being passed by the audio video leads.

[pitsch]

I think, most of the Thai houses have 3-pin plugs, but no earth wire connected to them. Has anybody actually seen an earth wire here?

[Nereus]

Another electrical question.

I have recently started to get a small electrical current running down the edges of my laptop casing (metal acer travelmate). UK plug plugged into an extension lead. Also experienced this on a DVR that has a metal case.

Any clues as to why this may be happening? I'm clueless with electrics!

You write that it is "recent'. From your other posts I believe that you have a new house. Has this been happening since day one, or only just started? It is not difficult to check and see if your outlet sockets have a ground (earth) wire. Apart from checking it with a multi-meter, you can carefully unscrew the wallplate and visually check for a ground wire.

If it has only just started doing it, and was ok to start with, it is possible that the earth conductor has either become disconnected from the grounding rod, OR, because it is now the dry season, it is possible that the lack of moisture in the ground has increased the resistance of the ground rod to the extent that it will not conduct. The resistance has to be very low, in the order of 1 ohm, and you would need a meter to check that. You may not be able to find the earth rod, assuming it has one, as it is very likely under the foundations of the house.

I am also a bit surprised that it is showing up via a laptop. The output of the power supply for the laptop is only 19 volts, and it is DC, so I suspect that you have some other fault. I also have a TravelMate, and the only metal on the case is the top cover, everything else is plastic.

[Lung Per]

It is a grounding problem. If you use a two-pin plug, perhaps your plug is turned so that you have phase on the metal housing. Turn the plug, that might do the trick.

[STEVE G]

It is a grounding problem. If you use a two-pin plug, perhaps your plug is turned so that you have phase on the metal housing. Turn the plug, that might do the trick.

I'd try that as well; if you've got a UK connector going to a two pin adaptor, it's possibe that the neutral is connected to the earth as it sometimes is in developing world electrics.

[Nereus]

Please enlighten me as to how the polarity of whatever type of mains plug, is going to affect the output of a DC power supply unit feeding a laptop??????

Yes, IF the mains supply was going direct to the laptop, then it is POSSIBLE to have the active connected to the frame. But that is not the case here.

[STEVE G]

Yes, if it's got a seperate power supply it shouldn't happen; I thought it was plugged into the mains.
You normally wouldn't be able to feel 19VDC.
I work a lot with 28VDC on aircraft and it'll give you a slight tingle if you're grounded, but that's all.

[Nereus]

It is a grounding problem. If you use a two-pin plug, perhaps your plug is turned so that you have phase on the metal housing. Turn the plug, that might do the trick.

I'd try that as well; if you've got a UK connector going to a two pin adaptor, it's possibe that the neutral is connected to the earth as it sometimes is in developing world electrics.

I think that you may have not written what you intended here, Steve.

The neutral is supposed to be connected to the earth in an MEN system, which is how the Thai system is supposed to be constructed. There are too many if and buts to come out and categorically state that it is an earthing problem, as has been stated on here. I am sure that you will agree, the only way that you can categorically state what the fault is; is to go and run some tests on it.

[STEVE G]

Yes,I agree with you Nereus, the earth is connected to neutral on the supply.
That's why I've had problems in the past with Asians wiring an earthed three pin adaptor with the earth to neautral on a two pin plug.
If you then plug it into a two pin socket the other way around the case of a metal appliance can become live which is actually quite dangerous.
I've had it on a PC and a washing machine in the past.
Obviously if there is a seperate power supply this won't be an issue anyway.

[poosmate]

If a new supply check that there is an earth connection. It is not unusual for the earth cable to be connected to the neutral bus bar in the consumer unit and not to a separate earth rod. I have also seen a so called electrician use a section of rebar instead of a copper rod. This will work but the resitance will be high especially in dry ground reducing the usefulness and safety.

[JimmyGreaves]

Thanks for all the responses.

The laptop is an acer travelmate 800 and the casing around the keyboard area is metal, worn now as I must have been using it 5 years +

Ok new house is earthed, 3 pin panasonic socket on the wall. 2 pin toshino 6 gang extension lead pushed into two of the 3 pins on the wall. UK 3 pin plug pushed into a gang on the extension lead. I get a small current on the laptop case.

DVR

Plugged directly into the wall with 2 pins no current on the case. Put the cctv cameras connections into the DVR using a safemax 4 gang extension (all 4 cameras have uk 3 pin connections) and the case tingles.

After reading all the posts looks it maybe the extensions. What to do? Buy new extensions? If so any ideas where and type etc etc

[Nereus]

Jimmy, I think that you are missing the point regarding the Laptop. Mine is also a TraveMate 800, and the case appears to be plastic, but may not be as I cannot find anything to check it with.

The point I am trying to make is that the Laptop has an in-line power supply, the output of which is electrically isolated from the mains, and is only around 19 volts DC. It is not possible to have mains voltage getting on to the case, and if the power supply is faulty to the extent that it was, then it would have fryed the Laptop.

You need to look elsewhere, such as something inducing static electricity onto the case, or is it sitting on some conductive surface? What happens if you pull the small DC supply plug out of the laptop?

Your DVD player is a different fault, as you have said that it is plugged direct into the mains, it points to no earth conductor. I have yet to find any off the shelf extension cables with 3 conductors, in places like Home Pro. If you can find some you need to make up your own extensions, and you will then find that you cannot buy the extension socket!

For your CCTV system the complete system should be on a UPS, This will not only give you continuous coverage, but will filter out all the crap that is on the Mains supply.

[JimmyGreaves]

Nereus, thanks for your reply


If I pull the power out of the laptop then the tingle goes away. The tingle is predominantly on the front left where the speaker port is and it also gets hot here. Maybe there is an internal issues something touching something, I rest my hand/rist here. Reluctant to open it up as it has too much acculated data on it and am slowly moving to a new laptop (slowly). Laptop is sitting on wood desk.

CCTV - Ok will defineteyl look for a ups, however still left with the cameras on uk 3 pin plugs. Can I leave them or do I cut them off and replace them with local ones?

All the best