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    by Miles Nicholson

    The US standard utilises line referencing rather than column/row or column referencing for the purposes of both cross referencing, but also wire numbering and component tagging. Some multi-national companies will adopt a drawing standard that is a mixture of International standards with vertical ladders along with line referencing to the US style along with IEC symbols.

    If this style is adopted using the IEC2, IEC4 or IEC-60617 libraries you may feel that the line reference markers are too large, especially when the rung distance is set to lower than 20mm and you’ve used a line reference number system that contains graphics e.g:


    How do you change these symbols?

    The symbol used depends on which Line Reference Numbers system has been adopted in the Drawing Properties:


    When you insert a ladder with line referencing, type LIST and pick the block to find the name of the block used from the IEC library.

    As an example for Sheet and numbers in hexagon, AutoCAD® Electrical uses a block called WD_MLRH9 & WD_MLRV9 dependent upon orientation.

    In this instance with a vertical ladder, the WD_MLRH9 block would need to be edited.

    As an example, open the WD_MLRH9.dwg from the IEC library that you utilise e.g. IEC2.


    Don’t simply scale the symbol at this point, as the symbol is a little more complex as it contains a further block within.

    Type BEDIT at the command prompt and highlight the block AW_MLR_USER.


    Select ACAD_Elec_Modify_line_MN_05.png

    Type SCALE at the command prompt.

    Select ALL.

    Base point 0,0.

    Scale factor 0.5 (example).

    Select ACAD_Elec_Modify_line_MN_06.png

    Save and Close the line reference number block.

    When used the new size of line reference marker will be used.