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I have this wire some of the inner part of which is exposed. My friend claims that this is highly dangerous, but I don't think that touching it would be lethal, and in the worst case scenario there might be a short circuit, though the plug is grounded (3-prongs). I don't understand enough to know this myself...

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    Down voting is counter-productive. There are some design aspects here and the educational value for current and future users is significant.
    – Russell McMahon
    Dec 6, 2015 at 23:19
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    I think the general advice here is similar to firearm safety: if you don't know if it's loaded, treat it like it's loaded. Since you don't know if the line is hot, treat it like it's hot.
    – horta
    Dec 6, 2015 at 23:33
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    Now what the advice has been given, this should probably be closed shouldn't it? "Questions on the repair of [..] must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design."
    – Rev1.0
    Dec 7, 2015 at 10:26
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    Guys, let natural selection happen.
    – Alec Teal
    Dec 7, 2015 at 14:14
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    @zabari - You said "but I don't think that touching it would be lethal" -> Comments on touching need to be taken in that context. If you thought it was safe (as you said you do) then you MIGHT use it as is and kill yourself, or a family member, or a friend or a stranger. Or you may convey your stated wrong and dangerous belief to others.
    – Russell McMahon
    Dec 8, 2015 at 5:35

5 Answers 5

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Given the colours (I don't know why the other answerer referred to a red wire, the wire in your picture is clearly brown) I'm going to assume you are somewhere in Europe.

The insulation on the nominally live wire is gone, that means you more likely than not have 230V exposed (if you are in a country that cares about polairty you definately have 230V exposed, if you are in a country that doesn't care about polarity it's 50/50). Touching that is very likely to result in an electric shock, if you are unlucky said shock may be fatal.

There is also earth exposed. With some movement you could end up with a short circuit. Most likely this will blow a fuse/trip a breaker but if you are unlucky it could also start a fire.

I would advise against using insulation tape to repair mains wires except in a dire emergency. It insulates fine but the adhesive can lose stickiness over time. If you do insist on using it make sure you remove the outer sheath, insulate the damaged wires individually and then insulate the bundle.

Best option is to replace the cable, if that is not possible then it may be possible to cut it and insert a suitable joint.

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    Since it is the wire on a plug, in most countries the colour is not a reliable way to distinguish between live and neutral
    – PlasmaHH
    Dec 6, 2015 at 15:36
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    True enough (though I don't actually see a plug in the picture). I still wouldn't be touching it.
    – Peter Green
    Dec 6, 2015 at 21:59
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    The dress is blue /the dress is black / the dress ... :-)
    – Russell McMahon
    Dec 7, 2015 at 5:31
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    There's always a chance that the colours are incorrect as well. Never assume that something is live or neutral because it has a specific colour!
    – pipe
    Dec 7, 2015 at 13:27
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    Unfortunately there is one particular type of plug that is earthed, unpolarised and very common. Also just because the plug is polarised doesn't nesacerally mean anyone pays attention to polarity when installing them. We brits are borderline paranoic about polarity but not everyone is.
    – Peter Green
    Dec 7, 2015 at 15:24
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Short: Yes - the wire is lethally dangerous

It could kill somebody.
It could cause a fire.

Longer: If that is a mains power cable, as it seems to be, then that wire has the potential* to be fatally dangerous if touched when power is applied.

Let's try that again

  • This can easily kill somebody

  • The lead could cause a fire - either by energy transfer from the bare wire to other grounded or semi grounded objects, or via the other also exposed conductor.

It appears to be a two conductor cable, but even if it has 3 conductors the danger is just as real. (The other visible conductor is also damaged, adding to the danger of electrocution and/or fire).

The colour suggests that this is the 'live' or 'phase' conductor, but even if the plug has been wired wrongly and that this is not the "Phase" conductor it could still kill somebody worst case.

Somebody has apparently covered the faulty area with tape which has been removed for whatever reason. The tape MAY make it SLIGHTLY safer but may not. If the lives concerned (yours or other users) are worth more than a few dollars then you should replace the cord or have it repaired competently.

enter image description here

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  • I'm guessing that * indicates you were going to write a footnote mentioning the pun, then forgot to.
    – user253751
    Dec 7, 2015 at 1:36
  • It's a 3-conductor cable. In the original (big) photo, the neutral wire (blue) can be seen underneath the other two.
    – Oleksandr R.
    Dec 7, 2015 at 2:54
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    @immibis So, do you mean to say Russell's hot post is a current example of wasted potential?
    – type_outcast
    Dec 7, 2015 at 5:16
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    Ow! I think these puns have the potential to be lethal.
    – candied_orange
    Dec 7, 2015 at 7:37
  • @immibis - Och aye - tis true. And now we have so many puns we hardly need anoth-er one. The 1st word of the answer may almost suggest a pun - though unintended.
    – Russell McMahon
    Dec 7, 2015 at 13:04
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You haven't told us which country you live in, or what this wire connects to. (It makes a difference if it's say, a refrigerator or microwave oven, as opposed to a small room fan.) Still, if it's connected to your mains (115/230V) power, as others have mentioned, your friend was right: that wire's a serious accident waiting to happen.

In addition to the excellent answers you've already received, let me add a couple things that I hope will be relevant not only to you, but others in similar situations:

Sanity check

Whenever I find myself pondering things like the following, a sanity check is surely needed:

My friend claims that this is highly dangerous, but I don't think that touching it would be lethal

I think an important test is that you've a) been told it's dangerous by someone who presumably cares about you, b) you have willfully rejected that advice, yet c) you haven't actually tried touching it yet! (DON'T try touching it. Please. Possibilities range from no sensation, to a light tingle, to cardiac arrest.) I'm glad you've come here for advice, and please consider getting your friend some flowers or something.

Mostly country-agnostic practical advice

Step 1. Unless it's connected to some actual life-support equipment or other vital systems, unplug that cord now, then cut the plug off so nobody else plugs it back in.

Now that your life and home are no longer in danger, you have a few options (subject to local law/regulation of course):

  • Check the device. If you're lucky, the entire cord may be removable from the back of the machine, making replacement cheap, easy, and safe.

  • Replace the entire device and recycle the old one. Especially if the device was inexpensive, and if you are not skilled with wiring, this may be a very reasonable option.

  • If permitted by local law, you can cut out the damaged section of cord and re-attach the plug (or attach a new plug if the existing one is damaged—the plug is not visible in your picture, so we can't tell). If the damage to the cord is too close to the device itself (say, less than a metre), the entire cord may need to be replaced.

    For an experienced electrician, either repair can be done in a minute or two with basic tools. There's plenty of info online, but I would suggest you check with a local electrician or home wiring adviser in your local hardware store. Hooking up a plug is easy enough, but you want to make sure you're not violating any local regulations. If your "fix" starts a fire, your home insurance might refuse to pay, and in some jurisdictions you might even be criminally liable.

  • If you perform any kind of repair, verify that repair with a multimeter. Some devices will operate with improper grounding, continuity, or poor connections, but may still be unsafe.

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    A comment on then cut the plug off; remove the wire from the plug once you've done this.
    – frodoskywalker
    Dec 7, 2015 at 9:55
  • @frodoskywalker Right, or my preferred method: toss the plug in a locked/private drawer until you're ready to either deal with it or dispose of it.
    – type_outcast
    Dec 7, 2015 at 10:08
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Yes, this is dangerous.

If any one touches the hot wire while he is grounded, the current will pass through him. In this case there is no benefit for the earth wire in that cable.

The earth wire is just for protection from the leakage current that leaks into the appliance of that cable.

Also a short circuit may occur if the hot and neutral wires touch each other.

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The other answers provide ample reason to suggest that the wire is indeed dangerous, however this is more general advice:

"Is this wire dangerous?"

Unless you are competent enough to determine this yourself (without referring to somewhere like this site), then you should treat it like it is dangerous and get someone who knows what they are doing to repair it.

Unlike a lot of DIY, electrics provide so many ways to accidentally kill yourself unless you know what you are doing.

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