Friday, January 30, 2015

Receptacle Family Example

This article comes from my Revit Basics Blog which I have decided to shut down. 

Electrical construction documents depend upon the use of symbolic representations of devices in plan view. The symbolic representation on a receptacle, for example is larger than the actual 3 dimensional modeled receptacle used for elevations and interference detection. It has to be to effectively convey the receptacle type and still be readable at an 1/8th scale. Because it is oversized placing receptacles close together in the model causes the plan symbols to overlap. That is unless the symbolic part of the family can be independently moved from the modeled component. Using a receptacle family as an example, this article will demonstrate how to do just that.

Begin by creating the symbolic annotation family of the plan symbol. Use the generic annotation family template provided with Revit. Name it “Family_A”. Using detail lines draw the plan symbol at the size it would be on a plotted sheet.

Controlling Up and Down Movement

Create another generic family. Use the generic annotation family template again. Name it “Family_AA”. Load “Family_A” into “Family_AA” to create a nested family. Place the nested symbology above the horizontal reference plane in Family_AA, but centered on the vertical plane. Draw a horizontal reference line under the symbology, and make it a weak reference.

Using an aligned dimension or the Align tool, lock the nested receptacle family to the reference line. Add a dimension from the reference line to the horizontal reference plane in “Family_AA”. Add an instance parameter to the dimension and name it “Offset From Wall”. This will add the ability to move the plan symbol away from the hosting wall or entity.

Create a third family using the Generic Face Based or the Generic Model template. Wall based or other options can be used here, so pick what works for to maintain company standards. In any case, the family will be built the same, but “push/pull” options are slightly different once the family is placed into the model. Name the new family “Receptacle”.

Create the following instance Parameters in the new family.

• Offset From Wall

• Offset From Wall2

• Offset L R

Create the following type Parameters in the new family.

• Plan Symbol

• Plan Scale

Load “Family _AA” into the “Receptacle” family and place it on the intersection of the two main reference planes. Assign the “Offset From Wall” in your nested family to the “Offset From Wall2” parameter in the host family by selecting “Family_AA” and selecting the box to the right of the “Offset From Wall” parameter in the Properties palette and then selecting the “Offset From Wall2” parameter in the dialog that pops up. This will allow the user to add a dimension to move the receptacle symbology off the wall without moving the model portion of the family.

Since the receptacle family scale is based on the plan scale, and it is unknown what that scale will be until it is placed in a view, a way push that information to the family is needed. Otherwise, an entered 6” offset may move the receptacle symbol radically more or less than 6” on the plan.  The Plan Scale parameter will be used as a mechanism for the user to convey the view scale to the family. At this time, Revit families do not have a parameter for the scale of the view they are placed in. Click on the Family Types button on the ribbon and as a default, set the “Plan Scale” parameter to 0’-0 1/8”.  To get the proper offset for any scale, add the following formula to the “Offset From Wall2” parameter “Offset From Wall / 1' * Plan Scale”.  The “Plan Scale” parameter must be manually entered by the user.

Controlling Left and Right Movement

To control the side to side movement of the receptacle symbol a vertical reference plane must be dimensioned and labeled. Revit will not allow negative values in dimensions, so the base plane can not be placed in the center of the symbol. To allow the offset to go both left and right of the center reference plane, add a reference plane to the 4’ left of the center reference plane. This sets the maximum offset, so adjust if required. Set the “L R” default to 4’, to align the plan symbol and the elevation symbol when families are placed. This plane should be pinned and set to “Not a Reference”. Create another reference plane and name it “L R”. Lock “Family_AA” to this reference plane, and make it a weak reference. Add a dimension from “L R” to the left reference plane, and set it to “Offset L R”.

If using a face based family, the “push/pull” grips to control the Left and Right location of the symbolic annotation now exist, but the offset from the wall distance must be manually typed in the properties dialog.

If using a generic family, the “push/pull” grips exist for control left and right as well as the offset distance from the wall.

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