help required

[leepy]

terminated old shower cable with junction box in loft no probs there also old fuse spur not used in bathroom pulled into loft also terminated with junction box when turning the juice back on ,on the ring the shower cable was reading live with voltage tester,but the 30 amp fuse for the shower is pulled out in the cu

 

[JohnD]

You could start by turning all the MCBs on and off/pulling the fuses out to see which one is feeding your terminated cable.

If this is an electric shower, 30A is not much. There might be another CU somewhere or if it is an old or amateurish installation it might not be fused at all...

Have you got a brown, Wylex fusebox?

 

[ban-all-sheds]

the shower cable was reading live with voltage tester

What sort of "voltage tester"?

 

[leepy]

hi thanks for reply ,the shower cable is 6mm it hasnt been used for a couple of years but when shower removed just pushed the feeding cable into loft and insulated it with tape and removed the 30amp fuse from cu and then today when i terminated a feed into bathroom which supplied fcu for a heater i turned of ring and terminated both the shower cable and the spur cable ,not touching the shower fuse has it hasnt been in for ages i just put my light pen tester on the shower cable and to my disbelief it glowed red and audible noise the cu is cartridge fuses i think wylex please help im worr ied

 

[JohnD]

Like I said, take out the fuses, one by one, to see which of them is supplying power to the cable.

Neon screwdrivers and the like are not well thought of here. they can give misleading results. Can you lay your hands on a multimeter?

If you put a socket and radio on that live cable, you will be able to hear it going on and off from downstairs when you pull the fuses in and out.

 

[leepy]

thanks jon i got it from cef it its just for detecting a live current it was about 25 pounds didnt relise there no good anyway when i first took the shower out a couple of years ago to identify which fuse turned the pull cord neon of i found the right fuse obviously and removed it which did isolate because i took the old pull swich out and pushed the wires up is this been live dangerous its terminated in a 30amp jb obviously theres a live co,ming from somewhere else is this possibly when the fuse is removed

 

[JohnD]

If it's a non-contact detector it might be misleading. You can get induced currents and other odd effects even when there isn't really any power on it.

Try putting a socket on the end of the cable and plugging something in, if you can't beg, borrow or steal a multimeter (they are available from £5 upwards). If there is supply on it, take out the fuses one at a time and see when it goes off.




If you are lucky you will have a herd of old sparkies on here in a minute telling you stories about how voltage detectors are rubbish. £25 is a pity.

 

[leepy]

hi jon when a put the ring main fuse in thats when it was live but how can it possibly be when the definate fuse is removed could it be static excuse me john for my ignorance

 

[leepy]

hi jon when a put the ring main fuse in thats when it was live but how can it possibly be when the definate fuse is removed could it be static excuse me john for my ignorance

 

[JohnD]

There might be something funny about the wiring that is making it live, or it might be that your voltage detector is misleading. E.g. you can get an induced voltage (at negligible current) transferring from two wires running next to each other. Can't tell from here, but you will soon track it down.

When you have found it, you can disconnect both ends of the cable, label them, and, like you have done, putting them in a box is better than taping the ends.

 

[Adam_151]

As john D says, these volt sticks are very sensitive, a cable or bunch of cables acts like a capacitor (afterall, it is two conductors separated by an insulator...) when a capacitor is subject to AC voltage, an effect called capacative reactance comes into play, its as if the conductors are connected to each other though a high value resistor (ignoreing the fundamental differences between ristance and reactance) so if one conductor is connected to the mains, and you 'sniff' for voltage on the other one, you'll see a voltage, but connect a load that is not of near infinatate impedance, and the voltage will disappear

 

[ban-all-sheds]

Keep the voltstick, and when you're older you can amuse your grandchildren by rubbing it on your jumper and making it light up.

In the meantime buy a multimeter - you can get quite a good one for £25....