Hi,

I have a new style "BT openreach external NTL box" on my brand new house. Basically, I think the developers have wired it up wrong, but I dont want to get them back to re-do it (time off work to be in etc). In the box is the clear connector with ports 2,3,5. Currently in 2 is a blue wire, in 3 is nothing, and in 5 is an orange wire. The line works, but not the ringer. If I connect the ringer wire (white with blue stripe?) into 3, the ringer works, but when you dial a number, the phone does not seem to register the dialling – i.e the ring tone remains. Also the dialling tone is noisy.

Am I right in thinking I need to disconnect the orange wire, as it is the "ring wire", which is not needed and causes interference?

sorry, NTE box (not NTL)

I would be careful working on a telephone line as ring current is dangerous. On a BT master socket there should be 2 wires terminating in ports 2&5.
Then there should be a capacitor and resistor arrangement. on the consumer side there should be ports 2 & 5 (Blue/white and White/blue)which is the loop to the exchange and port 3 (white/orange) which is the ringer wire. If there is no capacitor in there then you aren't in the master socket.
You need at least the 2 wires of the exchange line connected for the phone to work.
How many phones are connected to the line? More than a total REN of 4 and the ringer probably wont work. REN values are printed on the bottom of phones. Try disconnecting all extensions and just use one phone in the master socket to test it.

Piccie showing the above, fwiw:
http://www.wppltd.demon.co.uk/WPP/Wiring/UK_telephone/uk_telephone.html

I would be careful working on a telephone line as ring current is dangerous

Utter tosh! It's only 50v and the current is negligible!

The orange wire by my recollection is the ringer wire, but look it up on the web.

Or ask a mate to knock his master socket off and have a look to see what goes where.

Crackling usually indicates a poor connection.

BT can run a wrap test without making a visit. This is always their first step in fault isolation.

New master sockets have a test mode where you are in effect eliminating all of the wiring except the service coming in off the street up to the master. This enables BT to isolate the problem more quickly.

I sometimes pretend to be a telecomms engineer. What was it you wanted to know about, VOIP, Aloha protocols, ATM?

OIC – you actually want a telecomms technician.

On the 1st socket in the house (master) is where the 2 wires from the exchange connect. These should connect to connectors 2 & 5 – normally in the back part of the master socket. If you plug a phone into the master socket, it should work OK – try this 1st. IF you want to add extensions, you need to connect a wire from 2,3 & 5 to the corresponding 2,3 & 5 on the extension (non-master) socket and so forth to however many extensions you want (you can only plug in only so many actual phones or other devices – 4 otherwise the ringing doesn't work).

I sometimes pretend to be a telecomms engineer. What was it you wanted to know about, VOIP, Aloha protocols, ATM?

I would have thought that classed you as a datacomms engr. DWDM on the other hand….

ATM at least is widely used in telecomms bearers. Though I did say I only pretend – really a radio comms engineer – was trying to come up with some buzzwords people might recognise.

I would be careful working on a telephone line as ring current is dangerous.

<snigger>

It doesn't qualify you as an engineer at all. Telephone, datacoms, or washing machine.

The 50v across the line is harmless, though it does hurt if it zaps you. 😉

The 50v across the line is harmless, though it does hurt if it zaps you

*neg* 50v if you please. And it does bloody well hurt, I've been hit by it enough times during testing.

Volts are irrelevant to harm. amps is what kills.

Yeah, but how do you generate amps, TJ?

Ringing current will give you a smart if you are standing up the top of a pole in the rain and your ladder acts as ground, then again a telex line gives you a hell of a decent kick, but for a real whack then then some of the old PCM systems would give you a right belt 120 volts or so, never mind the entertainment you can have seeing how far a regen lid can go in the air if you don't de-pressurise the system beforehand.

Russ.. sells n designs the networks MicArms has to manage 😛

aracer – Member

Yeah, but how do you generate amps, TJ?

With a generator. 100000v at 0.0000000000000001amp wont kill.

Its the amps that count – the voltage is irrelevant

"The current is the controlling factor for Electrocution and Electrical Shock. The threshold for perception is about 100 microamps (0.0001 Amps). Also See Microshock Electrocution Hazards for currents less than 100 microamps. The National Electrical Code (NEC) considers 5 milliamps (0.005 Amps) to be a safe upper limit for children and adults hence the 5 milliamps GFI circuit breaker requirement for wet locations. T".

http://bassengineering.com/E_Effect.htm.

TJ, you should see the amps involved in Telecoms, massive solid metal bars used to conduct the power to the racks. I've seen pliers, screwdrivers varporise when dropped across busbars prior to them being insulated.

do they still run busbars around the exchanges then? I thought it all was just standard 2.5mm three phase cable after they went digital.

TJ – try Ohm's law. 100000v at 0.0000000000000001amp means you've got something with rather more resistance than the human body. That could be something between you and the voltage source, but in that case you don't actually get 100000V.

Aracer – you miss the point totally. Have a think.

Its not a steady state as in ohms law. Its a short circuit. thru the body which is not a fixed resistance. a few milliamps accorss the heart is what kills. If you get this few milliamps at 12 v or 12 000 v is irrelevant – its the currect that counts not the voltage or the power behind it

It's you missing the point TJ – Ohm's law applies whether instantaneously or in a steady state. If you've got volts you'll get amps. The only reason you don't get enough amps with a high voltage source is if there's something with sufficient resistance between you and the voltage source so you don't get full voltage applied to you.