Change a System Parameter from Type to Instance - Not Length

It is fairly common knowledge that we can change a built-in parameter like Width from Type to Instance by going through the side door, selecting a dimension assigned to the parameter and changing it to Instance on the ribbon (see the image).

Kurt Thompson wrote to me to share how he gets around this issue when the parameter isn't something a dimension can be associated with. Specifically he was referring to a thread at the Autodesk User Forums where a member (electrical focus) was asking Autodesk to change the default parameters for Mains (instance), MCB Rating (type) and Subfeed Lugs (type). They argue that each parameter should be the opposite of the current configuration based on how the information is really dealt with (not that he needs me to, but I agree with him).

Kurt writes:

"To change a System Type parameter to Instance...(specific to the mentioned thread)

Create a Shared Parameter built exactly like the built-in parameter you need to change but make it Instance instead of Type. Starting out with a Generic Model family, add the new parameter. Now assign the family to the category Electrical Equipment, Revit will replace the shared parameter with the built-in parameter but it will retain the Instance (or Type) property setting from the shared parameter. Give it a try."

Thanks Kurt!

Phases are Deleted - Electrical Issue - Cancel placing a wire

A client shared this issue with me a couple of weeks ago and Autodesk has acknowledged it as a bug. If you've already installed 2018.1 it has been patched, so the scary bit that follows has been dealt with.

The issue: Place the first node of a wire and then cancel (press ESC key for example) before placing the second node. Afterward, people find that their project's Phases are no longer available. In other words, the phases are not listed in the Phasing dialog box nor in the Phase parameter for elements, when examining the Properties palette. Also, the buttons that allow us to create new phases are disabled in the Phases dialog.

Bad bug! Fixed in version 2018.1.

Panel Name - Allow Unique Values per Group

Some time ago they added the ability to tell Revit we want a parameter to be able to store unique values even when the element is part of a group, like this.

That example is possible because it's a shared parameter. I find myself wishing that we could do the same thing for the built-in Panel Name parameter for electrical panels. These are unique identifiers in all the situations I've ever encountered. Never mind the unfortunate poor support for being in groups to begin with...

I wish that Panel Name could be like a Door's Mark parameter or a Room's Number...unique even when included in groups. I wish upon a star...

Open Sheet - Equal Rights for Panel Schedules

This new right-click choice exists, within the Project Browser, for views that are on sheets. Views that are real that is. Schedules are special views, they can be placed on more than one sheet (like Legends). Electrical Panel Schedules share this distinction but unlike other schedules they are not nearly as likely to require being placed on more than one sheet. Their schedule-ness makes this right click option invalid for them too.

I realize it probably isn't easy or perhaps even possible to segregate this schedule-ness from Panel Schedules but I would have found it very handy to be able to use the Open Sheet concept for them several times today. In this instance it would have been faster than navigating through a very long list of sheets. I suppose it is also possible that some firms do need to be able to put Panel Schedules on more than one sheet, in which case...bummer for me and my wish...

Revit MEP - Wire Size AWG vs MM

I wrote a post about this subject before. There is an app at the Autodesk Exchange Apps that offers trap door access to revise the bias toward AWG size versus.

It is called Convert Wire Size (AWG to MM) and it sells for $4.00 USD. I haven't used it myself but for those firms that need wire size reported in millimeters squared it may be the solution you need/want until Revit itself allows us to switch the criteria directly itself.

I'll be curious to hear how well it satisfies what engineers are asking for.

Revit MEP - Circuit Length Calculation

I received an email asking if I thought it would be possible to use a Line Based family to calculate wire length for circuiting purposes. It was prompted by reading an earlier post about using them for Egress Path calculation and documentation. I think it's a reasonable approach for Egress Paths because there is no such tool or concept already in Revit.

Electrical circuits on the other hand do calculate their length already, granted it does so simplistically. It combines the X/Y/Z distances of the devices from the panel (and each other) to arrive at a total circuit length.

A friend some years ago sent me a PDF that showed a bunch (a couple shown above) of different equipment and device layout schemes he did to better understand how Revit arrives at a value for Circuit Length. What it shows is that Revit does nothing to factor in obstacles which force the wiring to go up or down or around the things that are more than likely going to increase the total circuit length.

To be fair...how could it really? How detailed is the model? How long do we want the software to interrogate the model, the linked models to do a better job? It's a bit like requiring all conduit to be modelled, even 3/4" conduit feeding single gang boxes in a wall when there isn't a single stud in the model. Like with so many things in life, it's about context.

It's one thing to put a single gang box on a wall to indicate one is required here and another thing entirely to run conduit to all the way to it when you can't be sure it can really go there. Or like showing a pair of outlets back to back on a demising wall in a residential project where fire rating and sound attenuation would require them to be separated by a minimum distance.

Some things are still conceptual (schematic) in nature even in fairly detailed models. If we start modeling every stud then perhaps it becomes more reasonable to expect more system detail too. Then again if I have to create a run of (15) 3/4" conduits across a wall or ceiling I probably ought to model that situation because it's going to take up a lot of space and everyone else ought to be aware of it.

It's also been my observation that no matter how good software gets at a task there are always outliers that dismiss its results as still wrong. That written, it does matter and Revit should improve how it does calculations and how much say we have in the outcome because the length it calculates is also used internally to contribute to other calculations like wire sizing and voltage drop.

Setting aside how circuit length should be calculated (it might surprise you to know that engineers don't always agree on this), I'd consider this approach if my task was to determine how much wire was needed, a little closer to actual requirements than might show up in the circuit properties. I'd create a schedule focused on Electrical Circuits.

What you see above: I created a couple panels and added a bunch of duplex outlets. I assigned them to circuits. The schedule's second column is Revit's calculated length, no more effort on my part than placing devices, creating circuits and choosing a panel.

I sorted the schedule by Panel and then Circuit, provided a header for Panel and footer for totals. I added a parameter for Length Factor (a number) and then a Calculated Parameter for Total Estimate (a length) which uses a formula of Length Factor * Calculated (column 2).

Then I consider each circuit's circumstance and enter in a factor that increases or decreases Revit's own calculation according to how easy or hard the actual wire run or routing will be...or at least what I think it will be. A factor of 2 doubles the length etc. This calculation doesn't factor into load calculations like for Voltage Drop...but then neither would using a line based family.

This doesn't account for situations that might share a neutral (or ground) or runs that are comprised of individual conductors in conduit (like THHN or THWN) or a wiring combined into a common jacket like Cerro's NMB (a typical household wiring product).

That's the risk/difficulty of automatic calculations, the closer you examine situations the more outliers there are. It can be a bit like arguing about something being 99.6 percent correct. If it costs another $1000 to get to 99.9 or 100%...is that difference worth it?

Revit mEp - Design Master

I've been hearing good things about this add-on for Revit from Design Master.

If you're doing electrical work then you ought to have a closer look at it.

It has a tab for HVAC but it appears to only support AutoCAD for that, for now?

Revit MEP - Electrical Wire Size

Revit mEp is very American because it is hard-wired to do its calculations based on the AWG based wire sizes that are defined in the templates Autodesk provides to us. When you need to reference metric sizes/standards instead there is no place to change this bias and if you attempt to change wire sizes to metric equivalent (CSA or Sq. mm) values you'll find calculations, like Voltage Drop, either cease to work or you get strange results.

Working through this issue with a client recently they decided (or at least hoped) it would be acceptable to provide a chart that allowed the reader to cross reference the AWG size against the locally relevant size. This firm is based here in the USA but working on a project outside the USA. Perhaps in that context this could be forgiven by the client. I don't know how well that approach will work for firms that are working at home, outside the USA.

Fwiw, Autodesk IS aware of this bias. Providing more flexibility is among the many things they have to find time to include in future releases.

Revit MEP - Detail Callout Bias or Gotcha

Many of Revit mEp families use a nested annotation symbol to provide the standard graphics we are used to seeing in electrical documentation. Here's a little example of a few of these families.

If you created a Callout view and these symbols vanish my bet is that you've used a Detail Callout. Here's what a Detail Callout view of the same families looks like.

It's definitely a quirky thing, but these nested annotations in outlets don't show up in Detail Callout view. Feel free to start trying adjustments to Visibility/Graphics, Detail Level, Discipline and more...I've been down the road already. I'm pretty sure we're looking at a bug, or at least a conundrum brought about by the way these nested annotations work.

This view type is also fussy about creating other elements, like a room/space for example. As such I understand that this view type is intended as the last stop or end of the road with regard to drafting up a detail, for detailing not modeling with. It's just odd that these annotation elements won't appear in the view.

If you want an enlarged plan to show these annotation then avoid the Detail Callout, use the Floor Plan type instead.

Revit MEP - Conduit Run Schedule is Biased

I think it is a Reviteristic (read quirky or bizarre) that a Conduit Run Schedule will only see types that are created based on Conduit without Fittings. I'm pretty sure we'd all like schedules to include runs that use Conduit WITH fittings too. I understand that the fittings make it harder to provide a summary of a run but that's kind of the point isn't it, to do the things that are hard for us?

If we follow the help documentation advice to add a shared parameter to conduit and conduit fittings we can create a schedule that summarizes runs via a Multi-Category schedule. Unfortunately the very desirable and important Length parameter dies to us in that context, no joy there.

Revit 2015 R2 - MEP Circuit Sequence and Recently Used Panel

New Feature - Circuit Sequence

Somewhat related to yesterday's new electrical feature there is also a new Electrical Setting called Circuit Sequence. There are three choices: Numerical, Group by Phase and Odd then Even (a common request, to fill one side of the panel and then the other).

This helps determine how the next circuit that gets created is assigned to slots in a panel. Subtle but an important addition.

New Feature - Most Recently Used Panel

When we create a new circuit Revit now offers a list of panels on the ribbon, on the System Tools panel. It remembers the Most Recently Used Panel so creating a new circuit and assigning to a panel can be as little as two clicks. One click to select the electrical element and another to click on Power. As long as the correct panel is display in the drop down list box you can move on to another task. As you can see my favorite electrical panel is in the list already.

Subtle stuff makes me grin!

Revit 2015 R2 - MEP Move To for Circuits

Here's a subtle one for Revit mEp users, a new button shows up in Panel Schedules when you select a circuit.

Move To begins by selecting a circuit. You can choose another eligible slot in the schedule. You'll see the "No You Can't" icon at your cursor when you hover over ineligible locations in the schedule.

Revit will highlight eligible slots in the schedule by turning the cells green. If your schedule has a fixed number of slots and they are all filled up you'll have to reconsider the panel loads. You also need to move circuits up or down to create an open location. The Move To feature doesn't shift existing circuits around, it just moves a circuit a bit easier than using up or down when a slot exists for it to move to.

Revit MEP - Choosing a Panel

This is a quick tip I picked up eavesdropping on a conversation with Martin Schmid (Autodesk). When you create a circuit and use Select Panel the list of panels in the drop-down on the Options Bar sorts the panels based on their proximity to your circuit's elements. That's pretty subtle and I never paid close enough attention to notice. I love subtle stuff!

Revit MEP - Wish for a Secondary Option

When we select an electrical panel (Electrical Equipment category) Revit will display the Distribution System parameter on the Options Bar to make it easy to assign one.

I think the Options Bar is suffering from an ongoing case of nobody loves me anymore or at least an identity crisis of sorts. The persistence of the Properties Palette means that there is some redundancy between it and the Options Bar. We can change parameters in either place, Revit doesn't care. It's just a little confusing at first glance, at least for new users...but I digress.

Transformers have a parameter called Secondary Distribution System. I think it is fair to say that this parameter is overlooked easily and often. That's because it is hiding in the Properties Palette in the Electrical - Loads group, along with a bunch of read-only parameters.

Later when we attempt to use Select Panel it pokes us in the eye when we can't choose the transformer. I'd like the Options Bar to respond like this when we select a Transformer. Subtle change but adding it here would make this less subtle.

2014 Revit OpEd

Two Minutes with Two Kick Conduit Results

I wrote and created a video about this while Revit 2012 was current. A comment on that video asked if it still works for 2014. I find that it does but it appears to matter which direction we sketch the conduit. If we start at a horizontal conduit and sketch down to a vertical conduit we get this result. The transition from vertical to horizontal slopes up to the horizontal conduits.

If we start at a vertical conduit and sketch up to a horizontal conduit we get this result. The transition from vertical to horizontal only slopes at the sweeps of the conduit, remaining horizontal as long as the conduit can.

Your results will likely vary depending on the top elevation of the vertical conduit compared with the location of the ends of the horizontal conduits. You should note that I've assigned a bend radius in my example video. This video just contains captions, no audio. The original video contains audio that explains what I've done if you're interested.

Revit MEP Circuiting

I created a short video that describes the basic interaction between electrical devices and creating a circuit. It's really meant to help explain what happens when a device is already assigned to a circuit and we select it along with other elements that aren't circuited. The ribbon changes based on our selection and a circuited devices impairs our ability to create a circuit for the other devices that are eligible to create one.

• A device that is not part of a circuit, when selected by itself, will cause the Power button to appear
• A device that is part of a circuit, when selected by itself, will display the additional Electrical Circuit tab
• Multiple devices that are both part of a circuit and not part of circuit will only display the context ribbon relevant for the devices, no circuit tab or power button
• Selecting multiple devices that are assigned different electrical requirements will disable the Power button

When we select devices we need to be sure to glance at the ribbon for clues. Here's a video (no audio, turn on Captions).

I also wrote an earlier post about circuits if you're interested.

Load Classifications and Worksets

The early releases of Revit MEP didn't have a method to manage load classifications, they were hard wired (pun intended). It does now.

One downside of various sources of content is the way the family editor (person) assigns the load classification. It can be hard coded into the family (not nice), it can be assigned to a parameter instead (nice) and it can also be assigned a value in advance too (nice or not nice depending on who you are).

Load classifications are part of the project standards workset.

If you choose to be the "owner" of the electrical related project standards and not relinquish them there is still a back door that lets a new family introduce a load classification you may not approve of. Revit only seems to acknowledge ownership if you attempt to alter the existing settings, and that's only true if someone else has decided to make themselves the owner of the workset (Electrical Load Classifications). Loading a new family that has a classification like "Steve's Favorite Motors" will bring it along and add it to the load classifications.

This means trying to keep a handle on your load classifications can be a little troublesome has the project progresses. The electrical design team might behave but all it takes is a rogue HVAC user to load a new single duct VAV, that has its own notion of load classification, into the model (assuming multiple trades in one file).

Further, I think its odd that when I create a new Load Classification (like Steve's Favorite Motors) none of the electrical setting worksets show me as the borrower, especially the one called Electrical Load Classifications! If I change the load classifications I still am not considered a borrower, odd. What is odder still is that the worksets for Cable Tray Settings, Cable Tray Sizes, Conduit Settings, Wire Settings and Wire Sizes DO show me as borrower.

I understand that it might be better to let a family load completely and "sneak" in a new load classification than confront the user with a message about not being able to make a workset editable and refusing to load the family.

Best bet is to require content to be vetted for load classifications before they are added to the project model(s). Provide a list of classifications that the project electrical engineer wants to document. Also provide a set of "in this case, use this classification" examples to make it easier to tow the line.

Panel Schedule and Load Calculation Addition

A thread at AUGI that started in December 2011 described a situation that Panel Reports show some connected loads as "0". The thread wandered around a bit but Martin Schmid with Autodesk responded on Tuesday with some insight after the development team did some research. Martin prepared a video to help explain what can cause this.

He wrote in his reply at AUGI:

I was able to reproduce this today with some help with our development team. The issue seems to be related to having your connector's Load Classification Parameter associated with a Parameter that has an empty value specified.

You can see in the video that when I create a Load Classification parameter, it has no value... when I then associate that with the connector, the connector ends up with a load classification with no value. Thus, when you connect this, there is no value that propegates into the panel totals, since the panel totals are dependent on summing values from load classifications. As soon as I set a value on the parameter associatd with the connector's Load Classification, the values tabulate.

A reply at AUGI shortly thereafter reminded members to also check the Part Type setting for their families. Using stock content it isn't likely that this would be the issue but for any custom content that has been downloaded or created internally, checking everything you can won't hurt.

Electrical Panel Load Calculations

Another "inside" gem from Inside the System which offers deeper insight to how the numbers work. If you are a Revit MEP user and electrical is your game, then you'll want to read it. Thanks to Martin for taking the time to put it together.

Revit MEP Electrical Calculations

Martin Schmid has been sharing some deeper insight into the "magic" behind electrical calculations that Revit provides. Every engineer I've met is, not too surprisingly, skeptical about trusting yet another software for these answers. There has been data, in help documentation, to support the results but not quite as deeply as the last three posts combined. Check them out!

Why do I get different Voltage Drop results with Revit compared to the NEC?
To compute Voltage Drop, why does Revit use the formula VD=(L*R*I)/1000?
Why does the Revit Wire Impedance Factor table have separate sections for Three Phase and Single Phase?