Cable failure or me?

[top banana]

dear all, had a very unusual dilemma today while fitting my kitchen fan before carpets go down tomorrow.
Pulled cable through ceiling void and Linked brown to permanent live, grey to neutral, black to switched live, and earth to earth, in a junction box specifically installed for this purpose.
Went to test without switch and fan connected, and brown live at fan but switched live is also live. Bearing in mind the power doesn't get to the switch yet and the only wire that should be live is the permanent live.
I checked connections, triple checked the cables were correct, and stripped back the cables to see if they had connected ! Nothing!
So I pulled another length of 3 core and earth through and this time just connected the brown and nothing else. This time all three other cables were live. I cursed the cable manufacturers and pulled through a length of two core and earth, slightly bigger at 1.5mm and pulled a separate brown cable through with it.
I wired it all up feeling confident and wallah it's all ok!
My questions are , has anyone else had this happen? Is it the cable? Am I missing something?
I've tried a continuity test on the pieces of cable I used but it seems fine!

 

[Iggifer]

what are you testing for live with?

 

[flyingsparks]

We're you using a screwdriver with a neon inside yo test for live?
My bet is that you are, and this is picking up an induced voltage in the other cores. There was nothing wrong with the first cable you had installed.
This demonstrates why these screwdrivers are useless, you need a two probe tester to check what is live, and what is not.

 

[Iggifer]

We're you using a screwdriver with a neon inside yo test for live?
My bet is that you are, and this is picking up an induced voltage in the other cores. There was nothing wrong with the first cable you had installed.
This demonstrates why these screwdrivers are useless, you need a two probe tester to check what is live, and what is not.

i was thinking this but he said he tested continuity - so he has a multimeter at least

 

[flyingsparks]

True, but I bet he didn't use it to check for the voltage!
OP - can you let us know!?

 

[Taylortwocities]

I am rather concerned about all of this, especially this bit.

and pulled a separate brown cable through with it.

What sort of cable is this? Is it double insulated in some way, or is it just a length of wire?

 

[top banana]

Sorry just got the replies.
My multimeter battery was flat till this evening.
I tested with a screwdriver and a fluke voltage stick. I had a good length of separated cables so the stick wouldn't give a false reading.
The separate brown cable is a 1.5mm cable which I taped to the twin and earth.

 

[top banana]

True I should have used the multimeter.
I guess the only way to check the cable is to set up a similar scenario in the shed!

 

[top banana]

Got a feeling you are going to be right flyingsparks
First time it's happened to me.

 

[Taylortwocities]

As you will have probably guessed from the above, neon screwdrivers and voltage sticks lie to you, as they pick up induced voltages. That's why you have been led down the garden path.

Now to this length of brown wire. ALL cables must be double insulated. You must not run a length of conductor that is only protected by its single layer of insulation. It has to be double insulated (ie inside an outer sheath too.)

Sounds like you need to get busy re-doing that cable runproperly before the carpets go down.

 

[EFLImpudence]

Do you need a battery to test for voltage?

 

[top banana]

Taylortwocities thanks for the reply
Not what I wanted to hear, but I'll get it done.

 

[Robin0577]

Do you need a battery to test for voltage?

You do if you're using a standard digital multimeter, that's one of the reasons they're frowned upon as a means of testing for dead.

 

[JohnW2]

Do you need a battery to test for voltage?

You do if you're using a standard digital multimeter,....

I don't think you need to restrict that to "standard" digital multimeters. I can't see how any sort of digital meter could function without a battery of some sort (or a mains supply, if it were a bench instrument) - something has to power the electronics and display!

... that's one of the reasons they're frowned upon as a means of testing for dead.

AFAIAA, the same is true of most/all of the "two pole testers" advocated for 'testing for dead', isn't it? - again, if they have any electronics or a display they must have a power source (other thgan the voltage being measured). Only truly passive (moving coil or moving iron etc.) analogue meters could measure voltage without a battery (or mains supply) - and only us oldies are likely to have one of those Lamps (or LED equivalents) are another passive option, but they don't give a 'measurement' (LED ones may give a vague idea of voltage range).

Kind Regards, John

 

[westie101]

As an industry we are not allowed to prove live or dead other than with a two terminal test lamp
http://martindale-electric.co.uk/drummond-test-lamps-c-250.html
Even the use of a meter is not permitted