Spot Elevations on a receptacle family, where is the data derived from in plan?

[Anonymous]

I have a receptacle I built that contains a nested symbol with graphic options for GFI, etc.  The spot elevation changes it's reported value cycling the symbol.  Looking at the highlighted part in the project, it looks like it's anchoring to a nested part inside of the 'sym'.  The "Top" and "Bottom" options also come up ???

What actually drives these elevations for spot?  I've always assumed the pyhsical 3D shape, but that's not the case on this part.  The part isn't moving physically in the project, you can watch it in a section, but cycling a symbol graphic changes the spot elevation value by 4.5" (Total height of the faceplate.)

How can I use "Top" and "Bottom" Spot elevations in my family?

What drives the elevation on a symbol?

[Anonymous]

Best I can tell, even in plan view, you really need some 3D shape to drive a spot elevation.  Since I've set the 3D solid shape in the background off (Set visible off in plan/sections.) I used an unnested 3D shape in the family to drive the elevations.  Seems to work fine, even though it still doesn't explain the logic behind what hosts the top and bottom of a spot elevation?  would be epic if it simply read the elevation of the reference plane labelled "Top" in the family, but it does not.  The face plate is also an 'extrusion' in the source family.

[Anonymous · Accepted solution]

Additional research and follow up from an Autodesk support specialist, we were able to determine the Face-Based families rotate in plan view to match the orientation in the project browser.  So the Top/Bottom Elevation has nothing to read with the family technically turned on end.  (Face based families orient in a project so "PLAN" is actually "FRONT" in a family editor.  A localized nested solid fixes the trick, but I ended up using a Shared Parameter and a "Reporting" parameter to make a label record the correct elevation based on a reference plane, avoiding the Spot Elevation all together.  Instanced +UNO Note built into family.