This device can be fitted by the customer as it wired on the customers side of the demarcation point.

Made by Rotadata.

Installation Instructions

(Supersedes the Converter Ringer No. 15B)

The apparatus is intended for use only with the Plug Top Power Supply Unit supplied. Other usage will invalidate any approval given to this apparatus if, as a result, it ceases to comply with BS 6301: 1982.

Interconnection directly, or by way of other apparatus, to the port marked "Warning - Connect only approved telecommunications apparatus to this port" with ports not so marked, may produce hazardous conditions on the BT Network and advice should be obtained from a competent engineer.

The Converter Ringer No. 15C consists of a circuit module, housed in a fire retardant plastic enclosure and a separate plug top mains transformer. The Unit has been designed to allow at least eight telephones to ring simultaneously on a single Direct Exchange Line.

Under normal mains powered conditions the secondary line jacks connected to the output of the Converter Ringer No. 15C are isolated from the Incoming Exchange Ringing.  The ringing current for the secondary line jacks is generated internally by the Unit.  All telephones should be connected to the secondary line jacks to overcome any possibilities of "Bell Tinkle".

The REN is a customer guidance, indicating the maximum number of items of apparatus that should be connected simultaneously to a telephone line. To avoid problems on an exclusive line, particularly on Digital Exchanges, the maximum REN connected should not exceed 4.5.

Converter Ringer No. 15C REN = 3

The equipment comprises of:-
(1) The Converter Ringer No. 15C
(2) Plug Top Transformer Unit (2 metre cable)
(3) PST cable with Jack Connector (BT Std.CW 1311)
(4) 3 x 1" screws plus collet

Unscrew the long fixing screw, located at the right hand side of the Converter Ringer and remove the cover.

Utilising the three screws provided, fit the Unit to a suitable location (Fig 1) normally within 3 metres of the Master Line Jack Unit (MLJU) or NTE 5 (Network Terminating Equipment) and not nearer than 50 mm (because of Mains Induction) or further than 2 metres of a 13 Amp Mains Socket.

NB: It may be more advantageous to use utilise normal 8 wire connected to the IDC Connector of the NTE and run to the Converter Ringer rather than the PST Cable provided. This will increase the distance where the Unit can be fitted and more chance of making the position more aesthetic with its surroundings.

The Input Connections are made through the cable with the moulded BT Connector plugged into the front of the NTE/MJU or BT 8 wire* bifurcated into the DC (Insulation Displacement Connector) at the rear of the NTE/MJU. The cable provided may be shortened by cutting excess from the free end. Do not damage the end with the BT Plug. Allow sufficient length for the desired cable run. Strip approximately 1' from the outer covering at the free end of the cable to expose the four insulated wires inside.

Insert the cable through the Converter's casing, strip insulation and connect the four wires to the screw terminals (CN 4) as follows:-

Input CN 4 - BT Plug Ended Cord Provided   Input CN 4 - Standard BT 8 Wire
Wire colours Terminal   Wire colours Terminal
White 5   White/Blue Tracer 5
Blue 3   Orange/White Tracer 3
Red 2   Blue/White Tracer 2
Green 4   White/Orange Tracer 4

Using an 8 Wire cable (BT spec CW 1308) connect the Converter Ringer to the first Secondary Line Jack Unit (SLJU). The cable is connected as follows:-

Output CN1 - Standard BT 8 Wire
Wire colours Terminal
White/Blue Tracer 5
Orange/White Tracer 3
Blue/White Tracer 2
White/Orange Tracer 4

It is recommended that the 8 wire is squeezed between the fingers before inserting in Unit.


Make sure the PSU is unplugged.

Allow sufficient length for the desired cable run and then cut to size. At the Converter Ringer end, strip approximately 0.25" from the outer covering to expose the wire cores.  Insert the cable through the Converter Ringer casing and connect it to the 2 wire block terminal CN 3 (this cable is not polarity sensitive).  If power cable should need lengthening then a Block Terminal No. 80 may be utilised to extend the Low Voltage AC power feed with normal 8 wire.

If the Converter Ringer is being fitted on an extension of a PABX, it may be necessary to move the link CN 2 to increase the sensitivity of the Unit.

The link on CN2 is to the left hand side when in the normal position.

To increase the ringing sensitivity for PBX working move the link on CN2 to the right hand side.

Refit the cover and cover screw to the Converter Ringer. All cables may be cleated if required.

Plug the lead from the Converter Ringer into the NTE 5 MLJU and insert the Power Unit into the mains socket and switch on.

It is important to follow the installation instructions carefully. They ensure that telephone ancillary equipment and its cabling will not endanger the public telephone networks and will give trouble free service. The telephone service provider (British Telecom, Mercury Communications Ltd or Kingston upon Hull Telephone Department) is entitled to check and test any sockets (or wiring) connected to its exchange lines.

Connections to the Telephone Line
Each telephone exchange line coming in to your home or office must be fitted with a special master socket or Master Line Jack Unit (MUU) which must be installed by the telephone service provider. It is illegal to tamper in any way with this master socket and you cannot install it yourself.

Equipment and cabling not provided and installed by the telephone service provider may only be connected to your socket by plugging in direct or, if an NTE 5 is fitted, by wiring to the Customer connection unit (refer to NTE 5 Customer installation instructions).

Care must be taken in bending telephone cables to avoid kinking or other damage.

Equipment must always be placed at least 50 mm (2") from an AC mains socket and must not share wall fixings or back boxes with such outlets.

Do not plug new equipment into an existing socket until installation work is complete. If you are adding to sockets that are already in place and which connect to your telephone line through a plug, always unplug them whilst work is in progress.

There must not be more than 50 metres (164 feet) of cabling between your master socket and any extension socket. For similar technical reasons, the total length of wiring, including parallel-connected length, must not exceed 100 metres (328 feet).

Telephone cabling must at all points, be left at least 50 mm (2') from mains electrical cabling, except where a trunking or conduit system is being used, when the telephone cabling must be separated by a divider from any mains electrical cabling in the same trunk or conduit.

Where telephone cabling passes through a ceiling or floor void, it must be fixed wherever necessary, to ensure separation from mains electrical cabling.

It is recommended that telephone cables are fixed about every 300 mm (12'). Positioning

Approved sockets and cables are not designed for use outdoors or where exposed to undue damp or condensation. For good performance, installation should be avoided near to:-
Damp walls
Damp window sills
Newly plastered walls

Care should be taken to avoid damp conditions in kitchens, toilets and swimming pool areas.  Installation in bathrooms is not recommended.

Arrange for an Incoming Call and check all telephones and auxiliary bells ring correctly and efficiently.
It is advisable that the Mains is switched off and to demonstrate that at least a couple of telephones ring in the event of Mains Failure.