Is there a device to indicate if telephone wires are active?

[boilerfrustration]

We have lots of telephone wires strewn around the common parts of our building which is currently being done up. I've stripped out some of the wires which were clearly dead but there are others which I'm not sure about. Is there a device which can indicate if the wire is still active? As I'm not an electrician or telephone engineer, I would need a device which can detect a pulse from the plastic cable rather than the connecting end points.

 

[bernardgreen]

If the wires are in the common area then it is very likely they are the property of OpenReach (previously BT ) and you cannot do anything to them.

There are non contact testers / cable tracers but they are expensive and most often require that the end of the cable has a tone signal injected into it.

 

[BigRobCanUFixIt]

im affraid you will have to follow it to the end and measure should be about 50V dc with a multimeter.

Or if you know how many lines there are you could put a tone tester on the ones you know are working and use to probe to find those ones. and if it doesnt beep then chop em out.

you can pick up a cheap tester or oscilator they are sometimes called in cpc.co.uk for about 12quid (not sure how descent that one will be though)

if the office has a telephone system in though be careful as the tone wont pass through a pbx to all the extensions from the line.

BTs ownership of the cable will end at either a dp box or an nte. but they will charge a fortune if you balls it up.... so chop away

Rob

 

[Infidel]

This may help
http://www.amazon.co.uk/MULTI-PURPOSE-VOLTAGE-DETECTOR-TESTER/dp/B004TGMR8O
Not saying its any good but for less than a tenner, try it on a known working telephone circuit ie o/h lead in or extension cable.

 

[cajar]

Worth pointing out that even if they are dead, it doesn't neccessarily follow that they can be removed without being missed. BT might be counting on using them.

 

[bernardgreen]

There may also be circuits that are not exchange lines but "private" wires which are point to point links and not part of the telephone system. These are often tone only and do not have any significant voltage on them. They appear as "dead" when tested for voltage, they need to be tested for a resistive load on one or both ends and for silence on the pair. These are not un-common in office environments. Cut one of those and it could be very expensive.

 

[xr4x4]

The cables will only have voltage when the line is ringing, surly?

 

[Alarm]

Not the "private"wire ones.

Standard lines have 50vdc or less, with an AC voltage when ringing.

 

[Paul_C]

Standard lines have 50vdc or less

If there are DACS units mounted within the building, then on the exchange side of the DACS you'll see about 140V DC.

 

[simonpolly]

There may also be circuits that are not exchange lines but "private" wires which are point to point links and not part of the telephone system. These are often tone only and do not have any significant voltage on them. They appear as "dead" when tested for voltage, they need to be tested for a resistive load on one or both ends and for silence on the pair. These are not un-common in office environments. Cut one of those and it could be very expensive.

You would do well to take note of the above advice,some private wires don't even go via a exchange and are only used to link remote buildings via the openreach d side network,as above they will often carry no voltage and the only way of telling is to test and look for a loop on the end.Either way if you mess up expect a visit and a large bill from openreach if proven to be your fault.

 

[bernardgreen]

Either way if you mess up expect a visit and a large bill from openreach if proven to be your fault.

Not just from OpenReach. The customer who lost service can also claim for consequential losses.

I recall the incident when a building manager took out all the "redundant" phone wires in his building after a change of tenants. On the roof was a radio base station for a very important organisation. The building owners took a very heavy hit for negligence in not verifying each cable before removal and not having maintained records of which cables were not to be touched.