Dead power wire?

[mas0282]

Hi all. I wonder if someone can offer me some advice on an electrical wiring problem (forgive my use of layman's terms!).

In my bedroom I am trying to install an electric curtain track (a Silent Gliss 5400). This has an electric motor which takes two wires - a mains 240v power wire (permanently on) provides the power for the motor, while a low voltage core 4 wire provides switching for control of the motor.

So a few weeks ago before installing the curtain rail I tested the motor - worked perfectly.

I then installed the curtain rail. Now, when I try and get the motor to switch on - nothing. At first I thought it was the motor, but I now suspect the power wire.

I bought a wire tester (one of those neon screwdriver things as it's all I could get at my local hardware store). I know these things have mixed reliability but it seems to work fine on other wires that I know are live. When I test the power line for the curtain motor, I get mixed results - often I get nothing, occasionally it lights up (however, it also lit up a few times when the mains power was turned off at the circuit board so possible false positive?).

I've checked the circuit breakers. They haven't tripped.

Can anyone else think what I might try? Or can anyone suggest why there might now be a problem with the wire?

It just seems odd because it was working perfectly and now nothing. It's very robust piece of wire and was only installed a few years ago so I think unlikely it's suddenly just snapped/degraded.

It's possible that I might have drilled through the wire when installing the curtain rail but (1) the curtain track doesn't really look like it goes anywhere near the line of the wire (it's possible that the wire takes a really unusual route back to the circuit board, but seems unlikely), and (2) if I had drilled through a live wire isn't it likely I would have noticed?!

I am going to get an electrician out to check it but I'd just be interested to hear your thoughts.

Thank you!

 

[ban-all-sheds]

My thoughts are that all you can rely on the neon screwdriver to be is unreliable and potentially dangerous. I bet it's not even much cop as a screwdriver either.

You need an electrician or a multimeter.

 

[flameport]

if I had drilled through a live wire isn't it likely I would have noticed?!

Not necessarily. The cable has 3 wires inside, line, neutral, earth.

If you drilled through the line wire only while holding a plastic cased drill, nothing would happen as there is no path to earth, and no danger of electric shock.
If you drilled through the neutral, nothing would happen either, but your neon screwdriver would still illuminate as the line is still intact.
If you managed to drill through both at the same time, or earth and line, they would have been shorted together causing the circuit breaker to trip.
If drilling through neutral and earth, an RCD would probably trip if you have one, otherwise nothing.
All of the above would result in the motor not working.

 

[mas0282]

Thank you for the responses.

Can I assume that for an electrician diagnosing a fault like this should be fairly straightforward?

The power line runs from the bedroom into the RCD unit directly, so it's a fairly simple circuit.

 

[flameport]

To identify the fault should be a couple of minutes at most.

Fixing it is likely to take considerably longer.

 

[deadshort]

Hi, why don't you connect a lamp to the cable and try that ?
are you 100% certain there is not a fuse connection unit hidden some where? If the cable was installed a year ago how was it terminated ? If it was just sticking out of the wall it may not be connected at your 'RCD'.

You also need to ensure the motor is fused at the correct rating. The usual method of install is a non switched FCU hidden behind the curtains at the motor end of the track.

Regards,

DS