Nate Holt's Blog

January 31, 2011

Circuit Builder – switching from AWG to metric wire sizes – AutoCAD Electrical

Filed under: Electrical — nateholt @ 11:27 pm

How to define an alternate “electrical standard” to force Circuit Builder to default to metric wire sizes in its calculations.

Circuit Builder’s “Wire Size Lookup” dialog is a tool that can link into an “electrical standard” and guide you as you select motor size, motor power wire sizing, and appropriate ratings of the main disconnecting means – whether some type of breaker, fusible switch, or just fuses.

It can be launch from within Circuit Builder’s “Circuit Configuration” dialog as shown here:

The dialog opens and includes a number of different de-rating factors and settings. The results of the calculations default to AWG wire sizes. But one of the settings on the dialog can toggle calculations and display of metric wire sizes.

Let’s say you have a project that needs to use metric wire sizes rather than AWG. But you’d rather not have to remember to toggle to the “MM2” metric option every time the “Wire Size Lookup” dialog displays. You’d like it to default to metric wire sizes.

Setting up an alternate standard that defaults to metric wire sizes

Here’s how to create an alternate standard that parallels the default National Electrical Code settings for wire calculations but defaults to using metric wire sizes instead of AWG sizes. This avoids having to hit the AWG/MM2 toggle each time the dialog displays.

1. Launch the built-in Access database editing tool as shown below.

2. The Electrical Standards Database Editor dialog opens. Expand the “Default” and “NEC” tree nodes to show all table names. Find the table named “OPT_NEC”. Right click and Copy / Paste this table. Name the new copy “OPT_NEC-MM2” as shown below.

3.  Once you hit OK, the tree structure will update and add in the new “NEC-MM2” entry as shown below. Expand it to display the copied table OPT_NEC-MM2 and click on it to open. Edit the two “name” records highlighted in red. 

Here’s the key change. Edit the record marked with a CODE field value of “W_STD”. Change its DEFAULT field value from “AWG” to “MM2”. Hit “Save” and exit out of the database editor.


Open up any project. Right click on the project name in the AutoCAD Electrical Project Manager and select it.

Now run Circuit Builder and start to “Configure” a motor circuit. On the “Motor Setup” right at the front end, hit the “Select Motor” as shown below and make some motor selection. This sets in motion the queries into the select standard in the Electrical Standards Database file.

Select any motor size in dialog above and hit OK. Now cross your fingers and pop open the “Wire Size Lookup” dialog as shown below.

The dialog should display. Metric wire sizes instead of AWG sizes should now calculate and display. 

If there are other defaults you’d like to change, take a look in your new copied OPT_NEC-MM2 table and adjust.

Other Circuit Builder tutorials:

Tutorial – Introduction to the Circuit Builder Tool (Part 1)
Circuit Builder – Creating an Alternate Electrical Standards Setting
Circuit Builder – Leveraging AutoCAD’s “Group” Concept
Circuit Builder Configure Mode – Adding a “Pick from Icon Menu” Selection
Circuit Builder – Embedding Custom Calls in the Spreadsheet

1 Comment »

  1. Just fyi, I am using Autocad Electrical software for drwaing Electrical schematic wiring. It would be great if you can resolve the following issues as earilest.

    Query #1:

    How can I be able to add Diemension(Hight X Width X Depth) of an electrical component to a catalog data entry in the Catalog database so that when I place this component on a Panel Layout that should display the component according to the diemension given above. This will help me to avoid creating unnecessary nos of blocks of same look but with different dimensions. If this is not possible, then please suggest an alternative way to do this.

    Query #2:

    Does a MATCH property available in Acad electrical like in Autocad ? For example, I have placed 10 nos of Circuit breakers on a drawing page and I have to modify or hide or unhide one or two attributes of the first MCB. Then the same thing I have to do for other 9 MCBs. What is the shortest way to do this ?

    Query #3:

    How can I do bulk editing ? For example, I have the above MCBs in one page, all are 20Amps. I wanted to assign those with 4Amps each. What is the way to do this apart from Find and replace method as this may modify the value of an unwanted text containing 20Amps.

    Query #4:

    The utility function Projects–>Export to preadsheet–> Export to spreadsheet for a plc card IOs as attached file below works fine but While UPDATING from SPREADSHEET after few modifications in the IO descriptions in the excel file modifies few input terminal data for example the input terminal IN0 in the attached file changes to some other value. Why this is so and how to resolve this issue ?

    Comment by gaurav — December 7, 2011 @ 4:59 am

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