Volt sticks?

[newshound]

Just binned the two in my office desk, one a Kewtech (so not a Fluke, but not bargain basement either). Should I buy a Fluke, or two or three cheaper ones for the same total?

[Harry Bloomfield, Esq.]

newshound has brought this to us :

I always found Fluke to work well.

[GB]

If you had several, would these be kept in different places?

[NY]

Hopefully these work better than the one I bought from B&Q (model 18W51). That is *very* unreliable. The instructions tell you to test it on a known-live circuit before using it to determine whether a test circuit is live or to trace where a live cable goes. But it needs to be very close to a live wire or pin, and doesn't detect wires in a conduit in a wall. When did building regs (or normal electrician practice) change from using metal to using plastic conduits? I can imagine metal conduits would block any volt stick, especially if the conduit was earthed.

[John Rumm]

What was wrong with them?

I have been impressed with my fluke. In normal use it seems rock solid reliable. While expensive compared to some, they are not that pricey in absolute terms, so worth in IMHO.

I did try some experiments a while back to see if I could trick it into giving a false reading. I could not get a false negative out of it, but did manage one false positive - although had to try hard!

[newshound]

I have one or two in my workshop, but I find it increasingly handy to have some duplicate small tools in my office. In the days of neon screwdrivers I would always have several around, to have a spare if one decided to die. And, of course, always doing a positive test before relying on a negative indication.

[newshound]

Stopped working. The older one was very old, it may have been poor contacts on the mercury cells, but it also had a mechanical slider switch.

The Kewtech one was switchless, the batteries were fine and the contacts all looked OK (and I did tweak the springs to increase the contact pressure). It just didn't respond on thin, twin conductor desk-light flex.

Fluke it is then.

[Harry Bloomfield, Esq.]

NY presented the following explanation :

You can test one by rubbing the tip up and down your arm, to create static.

Their range is very limited, which is useful to identify L from N in bunches of cables, or in flexes. The range can be refined even more, by placing your fingers around the tip as a screen.

Why would you expect them to work through metal or screening? Either metal or plastic conduits are in use.

[Harry Bloomfield, Esq.]

John Rumm formulated on Sunday :

They are the best thing since sliced bread, if you thoroughly understand fully their limitations.

[NY]

As I said above, I *wouldn't* expect them to work through metal conduits. I presume that was one of the reasons (along with cost, weight and ease of cutting) for conduits mostly being plastic nowadays. Though maybe *good* conduit tracers can detect either induced voltage from live wires, for wires in plastic conduits, or can detect the alteration of a magnetic field (metal detector principle) for metal conduits, irrespective of whether there's a current flowing. Usually, the ability to trace where buried wires go is more important than to detect which wires are live - usually it's for working out where it's safe to drill or nail into a wall when putting up a picture etc.

I'm not sure how the batteries in my B&Q detector last as long as they do, because there's no on/off switch: it's permanently on and just bleeps (but very unreliably) when you put the tip near a current-carrying wire.

[John Rumm]

I find the "beep" facility quite handy at times - plomp it down close to a circuit you want to turn off, go to (typically unlabelled) CU, and turn off MCBs until the bleeping stops!

[Chris Green]

As I have changed and updated the wiring in our house I have labelled everything as I go. After 20 years of living here it now means just about everything is labelled. I have even put little stickers on the top edge of sockets to indicate which MCB/RCD feeds them.

I do check as well when working (i.e. have a lamp plugged in on the circuit) but it saves a *lot* of time being able to go straight to the right switch in the CU.

[charles]

Don't forget threading ...

[GB]

Pamper yourself. You deserve it. ;)

[John Rumm]

Yup good move - you quite often see that in commercial setups - each socket indicating what circuit/phase/CU its on etc.

Possibly overkill in domestic so long as all the sockets are when you would expect them to be according to the main CU labels. (e.g. if a "Downstairs Sockets" label on a MCB accurately identifies everything that is controlled by it without exceptions).

(although thinking about that, I have MCBs with Sockets Downstairs, Sockets Upstairs, and then a RCBO with Sockets Kitchen. So my Sockets Downstairs really ought to have "except Kitchen" added to its label!)

Sure does :-)

[John Rumm]

and bending

[Thomas Prufer]

[Harry Bloomfield, Esq.]

Nothing can detect live wires inside metal conduit, but metal conduit is easily detected with a metal detector buried several inches deep in a wall.

As above. It is not the magnetic field which is detected by a metal detector, they detect a change in inductance. The actual change depends upon whether it is ferrous or non-ferrous. Hence metal detectors can discriminate between the two.

[Harry Bloomfield, Esq.]

John Rumm brought next idea :

Yep, done that many times :-)

[charles]

yesterday I ordered some narrow tape so I could label an 'out of area' socket.

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