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CADArmor
Posts: 33
Registered: ‎10-20-2011
Message 1 of 9 (847 Views)
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Interference Check - Clash but no Clash

847 Views, 8 Replies
12-10-2012 11:28 PM

Can anyone please tell me why Revit finds hundreds of clashes that are not actually present? Please see image attached. I find myself working through hundreds of clashes with electrical lights/cable trays and fire pipes/fitting/sprinklers. Is there a way to fix this? I spend way to many hours working through clashed that are not there.

Please help!  

I found this out the hard way recently - the architect called us in a panic because we had hundreds of light fixture clashes. Apparently Revit considers the Light Source geometry to be part of the light fixture and includes it in clash detection! Neat! Turn on your light sources and I bet you'll see the clash. I have no idea how to resolve this however. Maybe Navisworks can exclude the light source geometry.

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abulla
Posts: 358
Registered: ‎10-14-2008
Message 2 of 9 (827 Views)

Re: Interference Check - Clash but no Clash

12-11-2012 06:32 AM in reply to: CADArmor

I found this out the hard way recently - the architect called us in a panic because we had hundreds of light fixture clashes. Apparently Revit considers the Light Source geometry to be part of the light fixture and includes it in clash detection! Neat! Turn on your light sources and I bet you'll see the clash. I have no idea how to resolve this however. Maybe Navisworks can exclude the light source geometry.

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CADastrophe
Posts: 3,421
Registered: ‎08-28-2009
Message 3 of 9 (826 Views)

Re: Interference Check - Clash but no Clash

12-11-2012 06:33 AM in reply to: CADArmor

Would it be an acceptable option to exclude the Pipe Fittings Category for the Interference Check? That would at least reduce the amount of reports. Otherwise, do you see any consistency - meaning, do the majority of the collisions stem from Pipe Fittings or another Category?

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CADastrophe
Posts: 3,421
Registered: ‎08-28-2009
Message 4 of 9 (823 Views)

Re: Interference Check - Clash but no Clash

12-11-2012 06:38 AM in reply to: abulla

abulla wrote:

"...Apparently Revit considers the Light Source geometry to be part of the light fixture and includes it in clash detection! Neat! Turn on your light sources and I bet you'll see the clash..."


I actually was just testing that with Revit MEP 2013 and the Light Source did not cause an interference. I verified that the "balloon" was immersed in a Duct (and then in a Duct Fitting) and there was no collision detected.

Corey D.                                                                                                                  ADSK_Logo_EE_2013.png    AutoCAD 2014 User  Revit 2014 User
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abulla
Posts: 358
Registered: ‎10-14-2008
Message 5 of 9 (817 Views)

Re: Interference Check - Clash but no Clash

12-11-2012 06:48 AM in reply to: CADastrophe

Huh... you're right. I can't seem to recreate the clash in my test model, even in 2012. Dang.

 

Update: OK this is strange. I can't get the default plain recessed lighting fixture to cause an interference with a pipe fitting, BUT when I load in a default recessed can light, the interference shows with the light source. I'll try it in 2013 as well.

pipe light interference.PNG

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abulla
Posts: 358
Registered: ‎10-14-2008
Message 6 of 9 (810 Views)

Re: Interference Check - Clash but no Clash

12-11-2012 07:15 AM in reply to: abulla

Yep it shows an interference in 2013 as well. But only with the downlight - I tried moving those pipes up into the 2x4 light source above it, and nothing clashed. Something about that downlight light source is causing a clash...

 

The only difference I can see between the two families is that the 2x4 light has a photometric IES web file associated with it, and the downlight does not.

 

pipe light interference 2013.PNG

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CADastrophe
Posts: 3,421
Registered: ‎08-28-2009
Message 7 of 9 (804 Views)

Re: Interference Check - Clash but no Clash

12-11-2012 07:28 AM in reply to: abulla

OK - more testing (RMEP 2013) and ANY Light Source Definition EXCEPT Photometric Web causes collisions!

 

To the OP, either:

  • Ensure that your Light Fixtures' Sources are set to Photometric Web.
  • Disable the Light Source setting for the Light Fixture Families.
  • Reduce the size of the light source of the Light Fixture Families.
Corey D.                                                                                                                  ADSK_Logo_EE_2013.png    AutoCAD 2014 User  Revit 2014 User
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Active Contributor
CADArmor
Posts: 33
Registered: ‎10-20-2011
Message 8 of 9 (791 Views)

Re: Interference Check - Clash but no Clash

12-11-2012 05:23 PM in reply to: abulla

Thank you problem solved! The reason for the clashes
was because of the light source. I went into electrical model,  opened a light fitting family and unticked
the light source in Family Category & Parameters. No more clashes found!

Valued Mentor
julianjameson8403
Posts: 458
Registered: ‎06-16-2010
Message 9 of 9 (543 Views)

Re: Interference Check - Clash but no Clash

03-28-2013 07:43 AM in reply to: CADArmor

An extension of this problem will also occur if you add coverage areas (Circlular model lines) to smoke detectors, security camera visibility cones, etc.

Although you can hide these sub-categories, they cause problems when selecting objects and interference checking.

Unless anyone has another way of dealing with these additions to families?

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