I have purchased a high quality surge protector of a known brand in my country featuring six outlets. However, when I plug the adapter of my laptop into it or the surge protector or plug the surge protector into the wall after I have plugged in the adapter of my laptop to it, I usually get a pop sound and a spark. In addition to that I have noticed that I get occasional electric shocks from the metal casing of my laptop when I have it plugged in this particular surge protector outlet and the adapter makes a humming noise when the laptop goes idle. What may be the reason behind this strange problem?

By the way I have two of these surge protectors and the electrical shock is still persisting even though I have replaced the surge protector with a normal power strip. How can I understand if it is related with the particular model of the brand or the particular product I am using(manufacturing defect)?I would also like to mention that this situation is pertinent to my home in Ankara (I also have a family home in Istanbul and none of the described issues occur there). Thus I suspect the grounding of the wall outlets. I also noticed a decrease in the life of the battery of my notebook after I have moved into this house.

1 Answer 1


If you notice none of the described symptoms when you plug the laptop adapter directly into the wall outlet then you should consider discontinuing the use of this surge protector / plug strip. This seems to me to be a serious safety issue that needs to be addressed immediately.

Once you get back to a safe usage scenario you should do some checking of the laptop adapter for safety issues as well. Remove the adapter from the wall power and from the laptop. Now using a digital multimeter in the resistance (ohms) measuring mode check for any low resistance readings (less than 10 megohms level) between any of the AC power leads and any of the contacts at the laptop charger plug end. If you find any low resistance connections from the AC to DC side of the adapter then you should replace that as well.

(Note that all of the numerous laptop adapters I have encountered are supposed to be 100% isolated from input to output. I.e. NO input to output electrical connection).

Now back to your surge protector. Some surge protectors may have installed components such as MOVs or high voltage capacitors between the AC lines (hot and neutral) and the earth ground connection of the AC wiring coming into the protector. If they are wired this way it is possible for some people to feel a slight shock when touching any grounded metal parts of equipment that is plugged into the downwind power jacks of the surge protector. In my electrical engineering opinion I do not think this type of surge protection wiring is the best idea. Now at the same time some manufacturer of a surge protector may boast that their unit is superior (and thus way more costly) if it has MOVs attached line-neutral, line-earth, and neutral-earth. This can lead to low level leakage currents from the AC line to the earth ground connection. If your "high end" unit is like this you should consider not using it!

If your laptop adapter has a connection from its input AC leads to DC output side and it is used in conjunction with a surge protector that has multi-MOVs causing leakage currents to flow then this can lead to the slight shocks that you feel when touching metal parts of the laptop.

My recommendation - safety first when dealing with anything electrical attached to the AC power lines. At first indication that there is something amiss discontinue use immediately.

  • Well thanks for you through answer, as far as multimeter is concerned I had one but left it in another city, so measuring the input impedance is not possible at the moment. I have warranty and bill of the surge protector strip maybe I should consider having it replaced. By the way why does this problem occur when the laptop goes idle?
    – Vesnog
    Oct 20, 2013 at 12:22
  • Only thing I can think of in regard to the idle is that in normal mode the laptop draws power at a much greater rate than when in idle. It could be that this increased power draw swamps out or cancels any possible leakage current that shows up in the idle state. I do not know where you are located but here in the US it is possible to purchase a low cost multi meter for just under $25 even from Radio Shack. For your problem this may or may not be interesting to you.
    – Michael Karas
    Oct 20, 2013 at 12:46
  • Well I am in Ankara, Turkey at the moment. Your proposal seems very logical actually if I had the opportunity I might consider hooking the laptop adapter to an oscilloscope, yet this is not possible. I am interested in pursuing this problem further and I might get a second multimeter. Are low cost multimeters reliable by the way? I almost forgot: see the second edit too please.
    – Vesnog
    Oct 20, 2013 at 12:48
  • Very well could be related to the integrity of the earth grounding of the outlets.
    – Michael Karas
    Oct 20, 2013 at 12:56
  • How can I identify an ungrounded outlet without a multimeter?
    – Vesnog
    Oct 20, 2013 at 12:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.