BT decided to use an Insulation Displacement Connections IDC system,  produced by Krone, on all their voice terminations in the field.  It was because of BT's buying power and the fact that BT commanded a such a presence in the business that other British companies adopted Krone as standard equipment.


Overview of the Krone Voice cabling IDC system
All these products use the IDC principle except where wiring above the specification.  In these cases screw terminals are used e.g. earth wires etc.

Each slot on an IDC connector can take two wires with a conductor sizes of 0.4mm to 0.65mm.  The principle of connection is that the wires are pushed into the IDC connector with an Inserters Wire No. 2A.

The inserter will push the wire home and then cut the free end of the wire off.  The inserter also has a fold out hook which is used to remove terminated wires.  This hook should always be folded back into the handle when not in use.

List of small Krone parts not mentioned above

Frames Mounting 5/20/8A        Used in BC 300 series - stainless 8 way
  "       "     5/30/10A       Used in BC 300A series - stainless 10 way
  "       "     5/5O/34A       Used in BC 500 series - 50 way

Plate Cable Fixing No. 1B      Screw fixed, 2 way
  "     "     "    No. 1C      Push in fuw BC 300
  "     "     "    No. 1D      Push in fuw BC 500 and FD 105A

Inserter Wire No. 2A           Terminating tool for SC 237's

Earth Clamp No. 1A             Terminates up to 35mm earth cable on FD's
Earth Post No. 5A              Earth terminal that fits into the square holes in BC250 and 300 series.

Cover No. 11A                  70mm low profile box cover

Rings Jumper No. 37A           Jumper rings for use in BC's

Part No 1/DPO/163              2 connector posts
 "    " 1/DPO/164              M3 x 6mm screws and part no 5/DSC/575
 "    " 1/DCL/183              Base clamp + 2 screws - for joining two adjacent BC's together.

Screw No. 8 x 12mm             For fixing items in BC 300 and clamping brackets

Wire Connector 9541	       2 wire B/Y - Y/B
  "      "     9571 	       3 wire G/W - W/G - R/G
  "      "     9573	       4 wire R/G - Bk/O - W/G - G/W

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Last revised: February 09, 2023