Detecting live wires

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Detecting live wires

Post by Piscator » Tue May 08, 2018 5:04 pm

Hi Everyone,

I'm not sure if this is posted in the right forum but can anyone advise of a decent live cable detector as I'm wanting to hang some photo frames and don't fancy a shock!
I bought one last week from a famous American online shop but the instructions are next to useless and I just don't trust the readings!
I don't want to spend much as I can't see myself using it all that often.
Any advice would be most welcome, many thanks.
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Re: Detecting live wires

Post by someone-else » Tue May 08, 2018 5:30 pm

You will find that they are all like the one you already have.........useless

The owner of this site made a video...........

Click here

There is no G'tee but cables should be run in the "permitted zones" Click here
Fret not, a forum is a collection of opinions. Above, are mine.

Which is correct? Metre or Meter? Click the link to find out more.

Working on anything electrical? have you got a multi meter? why not? Would you hit a nail with a shoe?

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Re: Detecting live wires

Post by Piscator » Tue May 08, 2018 8:20 pm

someone-else wrote:You will find that they are all like the one you already have.........useless

The owner of this site made a video...........

Click here

There is no G'tee but cables should be run in the "permitted zones" Click here
Just watched the video and the bosch dmf 10 digital detector looks even more useless than the one i have!
Appreciate the help, thank you.
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Re: Detecting live wires

Post by ericmark » Wed May 09, 2018 11:13 pm

There are some really good units, but at silly prices, I have a cheap unit, and it let me down, lucky all circuits in my house are RCD protected, however the two way light switch cable did not follow permitted zones, and did not get picked up with tester, so when I tapped two hack saw blades together to install a water supply for fridge/freezer I went through cable.

It knocked me to floor, took good 20 minutes to come around, and the RCD tested as tripping in 34 mS so it would have been a short shock at least. The problem was I was alone, and too embarrassed to go to hospitial, stupid but younger then.

Had I not tested, likely I would have been more careful. A pair of gloves would have saved me, holding a non insulated hacksaw blade was rather silly.
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Re: Detecting live wires

Post by kellys_eye » Thu May 10, 2018 8:50 am

I use a Fluke live wire detector. Fluke are a huge name in electronic test equipment and wouldn't produce something that didn't work. Don't pay 99p for one.
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Re: Detecting live wires

Post by Piscator » Thu May 10, 2018 2:37 pm

ericmark wrote:There are some really good units, but at silly prices, I have a cheap unit, and it let me down, lucky all circuits in my house are RCD protected, however the two way light switch cable did not follow permitted zones, and did not get picked up with tester, so when I tapped two hack saw blades together to install a water supply for fridge/freezer I went through cable.

It knocked me to floor, took good 20 minutes to come around, and the RCD tested as tripping in 34 mS so it would have been a short shock at least. The problem was I was alone, and too embarrassed to go to hospitial, stupid but younger then.

Had I not tested, likely I would have been more careful. A pair of gloves would have saved me, holding a non insulated hacksaw blade was rather silly.
You were very fortunate, I think its safe to say its not worth taking any chances when it comes to electricity - Glad you lived to tell the tale!
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Re: Detecting live wires

Post by Piscator » Thu May 10, 2018 2:39 pm

kellys_eye wrote:I use a Fluke live wire detector. Fluke are a huge name in electronic test equipment and wouldn't produce something that didn't work. Don't pay 99p for one.
I'm struggling find one, can you give me a pointer or send me a link to what might be suitable?
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Re: Detecting live wires

Post by someone-else » Thu May 10, 2018 3:06 pm

The item mentioned by kellys_eye is what is known as a "volt stick" (That is if you do what I did and google exactly that) A volt stick is of no use to you since all it does is light up / beep when it touches a live cable, as in, you have a bunch of cables and are any of them live.

You want to know where a cable is in the wall, a volt stick is no use for that.

There is however a fluke cable locator, but this has to be connected at one end of the cable (no use to you) and I will say nothing of the £600 price tag. (Yes really, £600)

so its a case of look up and down, left and right, wear rubber gloves, stand on a rubber mat, wear googles, wear ear defenders, wear a hard hat......etc
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Fret not, a forum is a collection of opinions. Above, are mine.

Which is correct? Metre or Meter? Click the link to find out more.

Working on anything electrical? have you got a multi meter? why not? Would you hit a nail with a shoe?

If gloom had a voice, it would be me. :mrgreen:

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Re: Detecting live wires

Post by kellys_eye » Thu May 10, 2018 5:54 pm

someone-else wrote:The item mentioned by kellys_eye is what is known as a "volt stick" (That is if you do what I did and google exactly that) A volt stick is of no use to you since all it does is light up / beep when it touches a live cable, as in, you have a bunch of cables and are any of them live.

You want to know where a cable is in the wall, a volt stick is no use for that.
The volt stick (Fluke) doesn't need to be physically touching a cable to indicate a live wire - it will detect a live cable behind plasterboard quite easily and if it can't then the cable is far enough away that a screw wouldn't hit it anyway. But that's not a good enough reason to simply rely on one.

In a proper installation, cables run in specific directions and locations i.e. vertically up from wall sockets (or down from them) and in a horizontal line between (some of) them. There are drawings to illustrate how cables 'should' be run and it's relatively straightforward to avoid the areas where the risk is 'substantial' without resorting to a cable detector.

The biggest problem is when cables have been added to mount wall lights although they SHOULD be vertically run too.

If there are no sockets above/below where you want to place a screw there is a very high likelihood there isn't any cabling either. Use a bit of common sense and avoid areas above sockets and light switches etc.
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Re: Detecting live wires

Post by Piscator » Fri May 11, 2018 3:12 pm

Once again some very sound advice here chaps, thank you :salute:
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