I'm having some problems at my new girlfriend's house. There was a extension cord that was giving shock and I changed to another. This one wasn't giving shock, but when I test it with that screwdriver that lights up a light on electricity, it lights up when touching the plastic part of the wire. The outside I mean. And it is happening with all the extension cords of the house.

What I want to know is if it is normal to the outside part of the wire to conduct correct or if maybe there is a problem with the house electrical system.

English is not my primary language, sorry for any mistakes.

Edit: on the others extensions of the house the light is on although it is very dim

  • 1
    \$\begingroup\$ that is not normal or safe... sounds like a possible missing neutral somewhere \$\endgroup\$
    – JonRB
    Oct 13 '18 at 1:32
  • \$\begingroup\$ You should get an electrician to look at the house. I'm not sure what could be causing that, but it sounds dangerous. \$\endgroup\$
    – Hearth
    Oct 13 '18 at 1:32
  • 1
    \$\begingroup\$ Please show a picture of the cords and tester in question. Is the "screwdriver that lights up a light on electricity" a non-contact voltage tester? \$\endgroup\$
    – K H
    Oct 13 '18 at 1:33
  • \$\begingroup\$ dropbox.com/s/vb35cxv7npuq4xi/IMG_20181012_223645.jpg?dl=0 I think it is. \$\endgroup\$ Oct 13 '18 at 1:41
  • \$\begingroup\$ need more info, where does the shock happen? this isn't a male-male cable, is it? is the shock in the middle, by the connection, or maybe at the end? \$\endgroup\$
    – tuskiomi
    Oct 13 '18 at 1:45

If you get an electric shock when touching the plug of the extension lead then it is likely that the plug and/or the wiring inside is at fault. From the pictures you showed, I would suggest removing the old plug and replacing it with a good-quality new plug, also cutting back the wire to start in a new place.

A neon mains tester such as you showed in another picture works by you being a capacitor (this is normal, nothing to worry about). There is an explanation at How does the tester screwdriver work?

I notice that the extension cord is only two wires. A safer version would have two wires with another insulator over them, like this:

enter image description here

(Image from the CPC website)

However, what I recommend is to buy a new extension lead with a moulded-on plug and socket. This accomplishes two things: it will be safe, and it shows you care.


If that “light-up” tester you are using is one to detect the PRESENCE of electricity without a physical connection to the wire then it is working correctly.

If that tester is one that requires a physical connection then there is an issue that has to be corrected - perhaps moisture on the surface could be the culprit...


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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