Ladders are the foundation of schematic drawings. Knowledge of automatic ladder creation and how to insert and edit wires and rungs enables you to efficiently create clean wire networks. Once these wire networks are created, you add component symbols and create parent/child relationships of these components to efficiently create schematic drawings. The AutoCAD Electrical software includes commands that automate the creation and modification of ladders. You can insert ladders at any point during the creation of a drawing. When inserting a ladder, you control its width, spacing, and reference numbers.
Creating Ladders
A ladder is created using the Insert Ladder command as follows:
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In the Schematic tab>Insert Wires/Wire Numbers panel, click
(Insert Ladder), or type aeladder at the command prompt. The Insert Ladder dialog box opens.
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Use the Width field to control the width of the ladder.
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Use the Spacing field to control the space between rungs of the ladder.
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Use one of three options to control the length of the ladder:
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In the Length field, enter a length. The number of rungs is calculated automatically.
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In the Rungs field, enter the number of rungs. The length is calculated automatically.
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Leave the Length and Rungs fields blank and pick points in the drawing window to determine the length of the ladder.
Length specified
Rungs specified
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Use the 1st Reference field to control the first reference number of the ladder. If a ladder already exists in the drawing, 1st Reference displays the next available number.
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If the drawing is set to use X-Y Grid or X Zone reference styling, the 1st Reference area of the Insert Ladder dialog box is grayed out and not used.
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Use the Index field to control how the reference numbers increment.
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Select Without reference numbers to insert a ladder without reference numbers (e.g., when adding ladders to drawings with X-Y Grid or X-Zones reference styles).
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Use the Phase area to define whether the ladder is single phase or 3 phase.
Single Phase
3 Phase
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Use the Draw Rungs area to control the geometry that is included with the ladder.
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No Bus: Inserts only reference numbers.
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No Rungs: Inserts only reference numbers and rails.
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Yes: Inserts reference numbers, rails, and rungs.
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Skip: Inserts a rung and skips a defined number of references before adding another rung.
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Click OK to exit the dialog box and insert the ladder.
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(Optional) To set a wire type, type T or right-click and select wireType. In the Set Wire Type dialog box, select the wire type in the list of available options, as shown below. Click OK to accept the new wire type.
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Pick the start position of the first rung. If you left the Length and Rungs fields blank, pick the position of the last rung.
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The default settings for the ladder width and spacing can be modified in the Drawing Settings dialog box.
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The ladder is inserted on the default wire layer unless a designated wire layer is set to current.
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Do not erase the first reference number of the ladder. It is the Master Line Reference (MLR) and carries the ladder’s intelligence. The other reference numbers are text fields and can be erased, as required.
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You can have an unlimited number of ladders in a single drawing, but they cannot overlap.
Revising Ladders
Once a ladder is created, you can modify its line references using the Revise Ladder command. This command does not change the lines or rungs of the ladder but updates the reference numbers along the side of the ladder.
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In the Schematic tab>Edit Wires/Wire Numbers panel, click
(Revise Ladder), or type aereviseladder at the command prompt. The Modify Line Reference Numbers dialog box opens.
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Change the values for the ladder you want to modify. The information for each ladder in the drawing displays in a separate row.
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Rung Spacing: Controls the distance between reference numbers.
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Rung Count: Controls how many reference numbers are present.
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Reference Numbers Start: Controls the first reference number for the ladder.
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Reference Numbers End: Controls the last reference number for the ladder.
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Index: Displays the increment between reference numbers.
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Redo: Forces an update of the reference numbers.
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Wire Number Format: Controls the information in the wire number. You can use the Electrical replaceable parameters or static text.
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Move and Back: Available if there are more than 4 ladders in a drawing. Click them to display the next set of ladders in the dialog box.
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Click OK.
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The Revise Ladder command only affects reference numbers along the side of the ladder and does not modify existing rungs. If you need to add additional rungs or remove existing rungs, you have to use separate commands to add or trim rungs after revising the reference numbers.
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You can also use other editing commands to modify the ladder, such as the AutoCAD Stretch command or the AutoCAD Electrical Scoot command.
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Changing the reference numbers does not affect component tags or wire numbers until Project-Wide Update/Retag or Automatic Wire Numbers is used to update these values.
Ladders are the first feature that needs to be set up before you start building your schematic drawing. In this blog post, I explained the different steps required to automatically create ladders in AutoCAD Electrical. I also showed you how to revise the ladders as per your requirements. Both these commands are explained further in ASCENT's AutoCAD Electrical 2025: Fundamentals learning guide.
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