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Paper Covered Conductor

Paper Covered Conductor

Increase in Dimensions due to the covering

The dimensions of the conductor and the covered wire shall be determined by the method described in Appendix A. The increase in dimensions due to the covering shall not exceed that specified nor shall it be less than that specified by more than the appropriate tolerance given in Table 5.

Tolerance on Covering

Increase due to the covering Negative tolerance
Over Up to and including
mm mm %
0.25 0.5 10
0.5 1.25 7.5
1.25 5



Unless otherwise specified the wire shall be wound on drums packed, wrapped and labelled in accordance with BS 2565†.

* Layer arrangements differing from those specified in this clause may be adopted by agreement between the purchaser and manufacturer provided that the wire meets all the other requirements of the standard.

† BS 2565, ‘Drums for covered winding wires and strips for electrical purposes for use in the United Kingdom.’

The insulating paper is wrapped firmly, closely, evenly and continuously round the wire. Construction, unless otherwise specified, is typically one of the following alternatives:

  • All papers are wrapped in the same direction with the inner paper applied with a butt lap. Successive papers are applied with an advance of 30-50% over the underlying paper with a maximum gap of (.79mm).
  • Papers are applied with butt intercalation in the following manners:
    1. 2 papers – double butt intercalation – advance 40-60%
    2. 3 papers – triple butt intercalation – advance 28-38%
  • Papers are lapped in the following manners:
    1. One paper applied with 47-49% overlap – equivalent to two papers.
    2. One paper applied with 64-66% overlap – equivalent to three papers.
    3. Two papers each applied in the one of the above manners.

The taping angle (measured between the paper and longitudinal axis of the wire) is normally in the range of 45-60 degrees, however, certain unusual sizes and constructions may necessitate angles outside this range.

Insulated Wire Dimensions

When build is specified only by number of papers there is no requirement for finished dimensions, however constructions of types (a) and (b) contain the specified number of papers, and type (c) shall contain the equivalent number of specified papers.

When build is specified the tolerances of the paper additions to conductor thickness and width shall be as specified in table P1.


Conductors under (6.35mm) thickness shall withstand 180 degrees flatwise bending around a mandrel 6 times the conductor thickness in both directions without exposure of the conductor.