Physical Vs Symbolic - Controlling Visibility of MEP Families

By Stuart Tanfield

One of the areas of Revit MEP that isn’t apparently obvious when building up your templates and libraries is the 2D representation of your electrical fixtures.

For those who have deal with AutoCAD libraries, you’ll understand exactly what I mean. When block symbols are placed in AutoCAD we don’t worry at all about the physicality of the socket we are representing, so we place our symbols conveniently next to one another. Well, with Revit that changes. We are required to think about all parts of the socket, the geometry and the symbolic representation.

If you use the Revit default libraries for your symbols, you’ll generally find you won’t have many issues, but from my time in industry, one of the first things to be recognised was the default symbol libraries did not match our symbols as well as being a little on the small side. So we entered into the task of creating our own libraries.

Due to the size of our symbols increasing, this resulted in our symbols overlapping one another when we positioned the physical sockets 50mm apart, and that’s the important part.

To explain this further, Figure 1 shows a couple of sockets in a plan view from the newly created libraries. Figure 2 reflects the actual position of the sockets positioned 50mm apart.

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Clearly the issue here, is that I have overlapping symbols. In an ideal world I would be able to move the socket symbol along, to position these nicely. If I move the symbol, this is going to take the geometry with it as well, and therefore increasing the spacing between the physical sockets.

The easiest way to overcome this hurdle is to introduce a parameter controlling the position of the symbol within the family as shown in Figure 3, which manifests itself as an instance parameter within the project area.

You may note the default position in this instance is set to 500, this is due to not being able to use minus numbers, thus allowing us to move the symbol back to a zero position.

Figure 4, demonstrates where we are able to move to the symbol to an offset of 350, which moves the symbol, whilst maintaining the position of our sockets positioned 50mm apart as indicated in Figure 5

The same method can be used to indicate multiple sockets which are “stacked”.

Typically we would like to indicate when sockets are placed above one another. Traditionally it is accepted to show sockets offset away from a wall to indicate this. By introducing a parameter (Offset Away From Wall), to move the symbol away from the way, we are able to achieve this as shown in Figure 6.

Creating your own libraries can be a huge time consuming task, and is certainly not something to be taken lightly. If you are spending this time, it makes sense to think prior to building your families, what you actually want them to do and what you want to get out of them. Careful planning will alleviate any rework later on.

If you require guidance on how to produce these types of families with these functionalities built in, please check the Cadline events page for upcoming webinars. 

For further information on this article please contact your Account Manager or call our Sales Team on 01784 419922 or email sales@cadline.co.uk​