When using Revit for electrical design, using Panel Schedules should be an important part of your design process. Revit provides the user with some default panel schedule templates with the software, but most organizations modify the templates to function and appear the way that they desire. Revit allows the user to do quite a bit of customization to the templates, but be aware that there are still limitations to the customization ability and some nuances.
Revit Help has instructions for basic electrical template modification. In this article, we will look at some aspects of customizing a template that are not so obvious to the user.
If you are utilizing Revit for electrical engineering design, then you are using electrical panels and likely electrical panel schedules. While the process of inserting electrical panels and connecting basic circuits to them is pretty straightforward, there are some items that are good to know to help you better utilize panels and their associated schedules.
First off, a requirement in this process is to make sure that after you place an electrical panel in the Revit model, you set the Distribution System for it. Otherwise, you will not be able to connect any electrical device or other electrical equipment to the panel. The Distribution System is shown in both the panel’s Propertiespalette, and on the Options Bar on the ribbon.
Panel Schedules in Revit are a report of the information that is contained in the electrical panel, and schedules cannot be created without having a panel family placed in the project file. They are not like a spreadsheet where the numerical values are entered into the spreadsheet. The values shown in the panel and on the panel schedule are a result of connected loads to the panel and are only as good as the information in the items connected to the panel.
As I work with electrical engineers who are migrating to Revit, a common question that I get is “How do I create one-line diagrams in Revit”. One-line diagrams, also called single-line diagrams, are an important part of electrical drawings for construction documents, so it is a subject that needs to be addressed. They are a simplified method of representing a 3-phase power system that shows distribution boards, switchboards, transformers, panels, breakers, etc., with lines illustrating the connectivity of the components of the distribution system. The diagram is not just for physical construction of the building’s electrical system, but developed by the electrical engineer during early stages of design.
The problem that you run into with creating one-line diagrams inside Revit is that the one-line diagrams are generally created before the equipment is actually placed in the Revit model. The electrical engineer will design the building’s electrical system by developing this diagram, then placing the electrical service equipment based upon the diagram.
Unfortunately, Revit does not provide a way of coordinating the one-line diagram with the actual electrical components placed inside Revit, either before the electrical equipment is placed or after the equipment is placed in the model.
I was recently exposed to an issue with electrical panel loads that illustrated what I feel are unique characteristics of how Revit circuit loads and Load Classifications affect the values that you see on the electrical panel schedule. If everything is utilized in Revit exactly as Revit is designed and intended, everything works fine. However, that rarely happens. Engineering firms create and customize families, and change or set Load Classifications which can impact the proper loading calculations.
Many companies have electrical panel schedules which display the Loads Summary at the bottom of the panel. This summary section separates each Load Classification into its own line so that you can see how much Connected Load exists for each different type of Load Classification and the Estimated Demand for each Load Classification. Those load values are then displayed as the Total Connected Load and the Total Demand Load that should include everything on the panel. The Total Connected Load is then displayed on a Switchboard panel schedule from which that panel is served. There are many different variations of how this information is displayed, but the general process is the same. Subpanels may also be involved, but the same issues exist with those loads.
In reviewing the issue, there were 2 different problems that were manifested in the panel loading. This article is an attempt to describe those 2 problems to help others understand what may be happening when load numbers don’t add up. I recommend everyone read the Autodesk Knowledge Network’s explanation of how Load Calculations are supposed to work. Read it at About Load Calculations.