Wire/cable length

[Anonymous]

Hello!

Explain me, please, how Revit MEP calculate the length of wire/ cable???!!!

Is this measure "true" - I want to understand the principle..

I want to make "cable  journal", but I dont want to calculate length manually.. same as in Acad..

And else one question - is how can I take in account the raise and drop of cable (maybe MEP counts them?). I dont want to draw conduit - we often dont use it in building...

Thank you

and Im sorry about my english.

Andrew.

[Anonymous]

If you are using rebit 2011, don't count on length or voltage drop.  A well known that will never be fixed.  If you rely on them, suggest you use another program.  Even if it did do you any good, anypast a panel schedule will not handle them anyways.

[Anonymous]

HI, jboone!

Where are you from?

Do you use such cable journal with a cables length?

How do you (in your company) get the summary - to buy cables.

I understand, that practice plays great role... Share your experience, please?

Thank you for your comments.

Best regards

from Russia.

Andrew .-)

[Anonymous]

I am from the US.  I assume you refer to what we call BX cables (prewired flexable conduit) or do you refer to data cables?  I work for a large AE firm is SC.  We don't use BX much on our designs, but we leave all the lengths to the contractor.  I think it normally comes on large rolls that are cut in the field.  I have never installed it nore seen it done.  If you spec it, you are responsible for it, even if it is wrong.  I would never imagine anyone wanting to specify lengths of cable unless this is for pricing?  Don't rely on revit to solve that for you though.

Are you using cable trays?  You should.

[Anonymous]

Hi!

We use cable trays and Revit gives us spec. But when we want to get lengths of cables - we have to calculate them manually... or simply give to custom dep. reference total length drawing on the experience.
I cant use summary from Revit spec to buy and cut cables in building process, because cable length is not true (if i draw cable using standart revit "wire" ). And I dont know, how MEP calculates it (i mean spec "Electric circuit", where voltage drop and mystery length)... Does MEP use coordinates of connectors?

How do you draw cable traces? Using only "conduit"? We use "wire" to make plan with cable traces. But then we have a problem to get true length... Maybe you can show me some your Traces plan if possible.

Thank you!

[Anonymous]

Sorry I can't answer these questions, but I believe that ribit 2012 is more accurate.  I would suggest you try maybe 100 random lengths after they have been circuited (wired), yes even data.  Suggest you examine through the system browser and check for systems that are circuited and do manual calculations on about 100 circuits and compare it to the ones calculated in ribit.  That will give you a good feeling for lengths are correct or near.

I also set up a system schedule which shows wire lengths.  It will probably be easier this way.  I should point out that the lengths can not be changed manually.  Your bad, lol.  The lengths shown in this scereen shot are longer than my building.  The length of building is 530'

[alan.skipper]

Neither Revit MEP nor AutoCAD MEP should be used for calculating cable sizes they are completely inaccurate and the facility should never have been included within these products, the are many other factors that need to be taken into account when calculating cable sizes which neither of these products address.

Revit MEP and AutoCAD MEP are not cable sizing products. I've said this many times in this forum that Autodesk do not talk to Electrical engineers especially UK ones, they are mechanical products with a little bit of electrical added on. They should be called MP with a little bit of E.

I would love for an Autodesk representative to come and visit me for a day but no one has offered.

Cheers

Skipper

[alan.skipper]

No response from Autodesk then??????

[Anonymous]

Unlikely you ever will.  We don't ever hear much from the internal workings of any products.

[Martin__Schmid]

The WIre Length functions in both AutoCAD MEP and Revit MEP are primarily designed for checking voltage drop on simple circuits with a single load, such as HVAC motor loads.  This is a very different design problem then estimating wire lengths for the purposes of tendering or other 'quanties', or computing voltage drop on 'branching' circuits such as receptacle circuits or site lighting.

The algorithm used is basically:

1.  Start with length = 0 

2   Start at the panel, set its location as the base point.

3.  Find the next closest device, its location as the end point.

4.  Compute the delta x + delta Y + delta Z between base point and end point.  Add this to length.

5.  Set base point = end point.

6.  For the remaining devices, loop back to 3.

In other words... start at the panel, and 'draw' a path to each device in a 'snaking' fashion with no branching , always going to the next closest device.

[jose.ar.vargas]

Martin,

I´m from Brazil, and this is the third time I come to this particular post when looking for cable length counting on the internet. I´ve been smashing my head against the wall for the last 2 months trying to figure out a way to workaround this deficiency in Revit.

I work as BIM Manager on an Autodesk CSI (Engmex Automacao de Projetos (http://www.autodesk.com.br/services-support/consulting/partner-programs/consulting-system-integrator... We are currently trying to convince customers to adopt Revit as primary 3D platform for Electrical Design. Unfortunatelly, we always get embarassed everytime we are asked about electrical cable calculations.

I´ve tried to work around with shared parameters, even though of creating an API for that, but it turned out to be ineficient, since Revit don´t ive API access to certain relations between object, i.e., if we could tell that from a panel to an equipment there is a certain conduit that links them, we could start the process of counting the cables that goes through it. But that is not possible through API.

And about what our colleagues said, I know that Autodesk doen´t guess what our Electrical Designs need. And it´s too unfriendly to guess that at Autodesk are a bunch of programmers that simply don´t care.

We have the power, as users (I believe that, correct me if I´m worng Martin), to address those problems to Autodesk, intrusting them to hear from us and to changes to improve the software. There is a specific form for that if you have a subsciption. So, many are the ways to communicate demands.

If I could talk with Autodesk face to face, would be great, but here in my country there aren´t many personal events to attend to with the development team from Autodesk. There is the Revit Gunslinger Event (now called Inside the Factory) that happens in August and November in Waltham, Massachussets. Free acommodation. Ok, plane tickets are not cheap, but if you really want to have a saying in anything, try to go after what you want, not just complain in forums. I havent´found in any a workaround for that, seems that everybody just gives up when finding a problem. Or not, I could be unfair in that sense.

But I´ll try to pursue my goals to the end with Autodesk. I´ve liked what they have done so far in many ways, specially for BIM. But the Projects are the most important thing here. If the software limits you, them it should be questioned to be changed.

Bentley´s AECOsim does wire counting correctly, but it´s way too expensive in comparison to Revit. DDSCAD is also an alternative, far less known, but seems to be efficient in Electrical Design.

[alan.skipper]

There is no E in MEP...... The electrical content in MEP is non existant.

[jose.ar.vargas]

Sorry, but do you say Modeling or setup? The 3D model or the inteligence?

I have to disagree in both, since Revit does understand circuits, wiring is
limited, but is connected to the circuits.

So, I take your answer as just complaint, without reason for it.

I would recommend to take another software as tool of use, if you just want
to say "Revit don´t do it".

As I say, other softwares have the capabilities lacking in Revit, but the
cheap ones, that claim to be great, actually doesn´t have any BIM
capabilites in them, they are stand-alone platforms. On the other hand,
AECOsim is the top one, but too expensive for small companies.

Att.

Best Regards,

José Antônio R. Vargas
Engenharia Mecânica - PUC Minas
Administrador 3D - AutoCAD / Revit / Inventor

[jaboone]

Perhaps jaribeirovargas would like to shed some light on what it is we are all missing in our complaints because I think none of us have found effective methods of getting the two most important aspects of electrical to be so hard to mesh as they should be. If there is a method for getting wire and conduit in one place I would love to hear it because I/we haven't heard of it yet.

[jaboone]

You should also look at EPS Pro from Powersoft Engineering. Cheap and takes text imports from Revit.
www.powersofteng.com

[jose.ar.vargas]

There are workarounds you can do, if you specify shared parameters to
conduits so you can make your wire counting. in our case in Brazil is more
complicated because we have to tag conduits / cable trays according to the
number of circuits that goes trough them and how many hot conductors,
neutral, return and ground wires, and we also have to list thickness of
cable on those tags. That helps workers to rapidly identify circuits and
place them on the field, or even to help planning the pre-assembly of
wiring before the construction.

Thus, we have a parameter for Circuit Number, number of HC (hot
conductors), NC, GC, RC, and so on.

It is not admidtly the most effective way, is laborous for the modeller,
but it gives us the ability to extract the information we want from the 3D
model. Tagging is tricky because we have to make it read all of those
parameters from a conduit, and if you have more than one circuit going
through it, we have to work with formulas, so we can either see or not
symbols for hot, neutral, return and ground wires.

So, thank you for the cortesy of the question. 🙂

Att.

Best Regards,

José Antônio R. Vargas
Engenharia Mecânica - PUC Minas
Administrador 3D - AutoCAD / Revit / Inventor

[jaboone]

Have you ever been able to get it to a panel schedule too. I would love to see some of these things and even a panel schedule too, please.

You did say laborious as I can believe. We are saying it should never have to be that complicated to find our basic fundamental properties, that is all we are saying. I don't think aanyone in more than 100 peopel would want to take the steps required to go tas far as to learn something we don't like in the first place or would have the years of experience it would take to even go more than one project with this sort of deficiencies and .oversights.

[jose.ar.vargas]

Maybe you could share insight with Autodesk about this sort of software, so
they can learn about competitors and get to think about the customers they
loose from those deficiencies. How can anyone, a person or a company learn
anything new, or fix what´s wrong, if no one tell them directly about it.

That is my questioning for you guys. EPS seems to be made for work of only
one designer / engineer. What about collaboration? 3D modelling? Project
coordination? Clash detection of systems and disciplines?

I first didn´t see any thinking about the subject of scheduling in Revit,
only complaints right away. At least I gave it some thought before reach a
conclusion.

Give it a thought, mate.

Best Regards,

José Antônio R. Vargas
Engenharia Mecânica - PUC Minas
Administrador 3D - AutoCAD / Revit / Inventor

[jaboone]

Sorry, it never dawned on anyone, I think, that anyone in the world had actually solved the problem of conduit and wire and we assumed the farm was aware of the cituation but just chose to sweep it under the rug so to speak.  Out of the hundred or so people I have spoke to here in the US, no electrical engineer likes revit because of these laboriase things to name a few.  We have been spreading the word on deaf ears for years.  No one has got it yet.

[jose.ar.vargas]

I have this document, that goes to Autodesk´s Development Team. That´s the
way they have to reach for the customer, but it´s a feature that I´ve only
seen available for subscription.

It´s a detailed guide to troubleshooting and a kind of Wish request to the
guys that actually put their hands on the software.

I agree that the employee from Autodesk haven´t been very present in this
particular post. But I believe new things comes from persistence.

So, if it interests, there you go. Hope that you could even help me get
those features introduced.

It doesn´t cost us to try, right?

P.s.: Guys from Autodesk, let´s pay attention to the forums.

Att.

Best Regards,

José Antônio R. Vargas
Engenharia Mecânica - PUC Minas
Administrador 3D - AutoCAD / Revit / Inventor