1-I am using revit mep 2013 and it enables me to add new materials for wire , ampacity and diameter why the cable constant for voltage drop is not editable also
2-the wires calculation refers to single core cable not for multicore
3-the wire csa in AWG not in sq mm
Regarding number 1, it looks like you can change the "Max Voltage Drop For Branch/Feeder Circuit Wire Sizing" in the main Wiring section (the defaults are 2 and 3 percent).
thank you very much for your interest
but I mean by cable constant for voltage drop is not editable (mv/amp/m)
the factor that multiplied by ampere and length to get the voltage drop
Thank you for the clarification. After looking into this further, I have found the following help topic that says (in the Wire Impedance Factors section) "For the purposes of Voltage Drop calculations, Revit MEP always assumes Copper conductors."
http://wikihelp.autodesk.com/Revit/enu/2013/Help/00001-Revit_He0/3251-Referenc3251/3252-Electric3252...
With the introduction of Electrical Resistivity values for materials in the 2013 software, it would be possible to switch from using a lookup table for the impedance, to using the value based on the actual material, and I have brought this up with our development group.
If you would like to provide your own feedback to our developers, you can use the following link:
http://usa.autodesk.com/adsk/servlet/index?siteID=123112&id=1109794
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