MEP blocks scaling up from xref to host drawing

[Burns.229583]

A drawing-specific issue never encountered before is changing the size of MEP blocks from xref drawing model space to host drawing paper space.

When placing a "Wall-Mounted Light Fixture" for example in an xreferenced drawing, the circle part of the light fixture might start out 9" in diameter in model space at 1/8" = 1'-0", but when viewed in a paper space viewport through an xref (also at 1/8" = 1'-0") it gets scaled up 1/3, to 12" in diameter.
The scaling is centered around the origin point, so the block will also appear to move in space relative to surrounding walls, etc. depending where the origin is located.
This scaling occurs for all MEP objects in the xreferenced drawings affected and always the same 1/3 scale factor.

AutoCAD HELP points me to scaling of objects, annotative blocks, and viewports, but all of these are set correctly and work fine for non-MEP objects.

My frustration level is overflowing.

[dkoch]

Does your light fixture use annotative scaling? (I would think a real-world object would be drawn to actual size, but perhaps these are just symbolic representations.) ACA/AMEP annotative content uses two things to determine the scaling: the drawing/viewport scale (1/8" = 1'-0", in your case) and the annotation plot size (set on the Drawing Setup dialog, Scale tab). Based on the ratio you are experiencing, I would guess that your source file has the annotation plot size set to 3/32" but your host file has it set to 1/8", resulting in the annotative content being 133% larger.

[Burns.229583]

Thanks for the reply...I just read it today.

So I checked your suggestion and find both scale factors you identified set correctly, that is: 1/8" = 1'-0".
I've looked to that and for other causes to this problem but find nothing.

Attached are two .pdfs showing the xref model space and the host paper space.
The text and arrowheads are annotative and the MEP objects scale like annotive objects.
I added a hidden line to indentify the location of the origin of each MEP object.
Please note how only the MEP objects scale up (by 1/3), around the Origin point.
This changes their size and relative position, of course.
Nothing else scales up.

[dkoch]

In each of your files:

Type AECDWGSETUP at the command prompt.
Select the Scale tab in the Drawing Setup dialog.
At the upper right, note the value in the Annotation Plot Size edit box.

For both drawing to show MEP content the same way, this value needs to be the same in both files. I suspect it may be set to 3/32" in one and 1/8" in the other. Set both to whatever value you want as your typical (minimum?) text height. Check any other files you are using and your template file(s) to make certain your preferred value is set in all.

[Burns.229583]

that solved the problem.
i'm totally impressed...many have confronted this problem at my job, but none could identify it. you're awesome!

funny how i've seen the dialog box many times before, but never associated it with my problem here.

we use 3/32" sized text, but the host drawings were set to 1/8", which scaled up everything MEP.

i intend to spread the word to my coworkers.
hopefully this post will spread the word to other users confronted with this most annoying issue.

thanks again dkoch.