Fire Alarm Design Basics in Revit
While you may have some experience placing fire alarm devices in the Revit model for presentation and collision detection purposes, you're less likely to have used all of the features Revit offers to design a fire alarm system. Many of the tools FireBIM provides depend on appropriate use of Revit functionality.
This section outlines the key Revit concepts you’ll need to be familiar with to start designing fire alarm systems, and how that foundation supports FireBIM.
Families & Parameters
Most elements in the Revit model are based upon a family—a reusable collection of geometry and data. Fire alarm components such as control units, detectors, and notification appliances are all family-based elements. The elements you insert into the model are family instances. Information on elements can be set at both the family level and the instance level.
Parameters control the behavior and data stored in each family. These include built-in Revit parameters and custom shared parameters, which may store voltage ranges, standby and alarm currents, and other relevant information.
To use these effectively, you’ll need to know:
- How to define families, including creating family types and modifying parameters
- How to load families into a project
- How to insert instances of a family in plan views
- How to modify parameter values for each instance (or the type as a whole)
While standard Revit allows users to make changes to devices by modifying their parameters directly, FireBIM parameter values must be changed using the appropriate FireBIM commands. Any direct changes made to FireBIM parameters will be overwritten by the last information fed into FireBIM. Visit the Making Changes section for more information.
Family Categories for Panels & Devices
To ensure proper circuiting and categorization in Revit, fire alarm components must be assigned to the appropriate Family Category:
- Control units, annunciators, amplifiers, and similar items must be categorized as Electrical Equipment. In addition, their Part Type parameter must be set to Other Panel.
- Detectors, modules, switches, strobes, speakers, and other devices must be categorized as Fire Alarm Devices.
Electrical Connectors
All fire alarm panels and devices must include at least one Electrical Connector so they can be connected using Revit's circuiting functionality.
You will need to know:
- How to add an Electrical Connector to a family
- How to assign a System Type to each connector:
- Use Power - Balanced or Power - Unbalanced if the panel or device needs to be circuited to a 120VAC electrical distribution
- Use Fire Alarm if the panel or device needs to be circuited to other fire alarm devices
For devices with multiple circuit connections—such as a combination speaker/strobe, or an annunciator with both communication and auxiliary power connections—each circuit must have its own connector.
Fire alarm panels must include at least one Fire Alarm connector for FireBIM to recognize them as fire alarm panels.
Annotation Symbols
For devices and panels to appear diagrammatically on Revit plan views, they must include annotation symbol families. You will need to know how to load annotation symbol families into your panel and device families, particularly to ensure that your devices display floor plan symbols that will match symbols in the riser diagrams you create using FireBIM.
Circuiting Panels & Devices
Revit allows you to create and manage electrical circuits between panels and devices using its Electrical Systems tools. These circuits must be modeled correctly for FireBIM riser diagrams and calculations to be accurate.
You will need to know:
- How to use the Power and Fire Alarm commands that appear when selecting an instance with an electrical connector
- How to connect devices and downstream panels to upstream panels, forming logical circuits
- How to add and remove devices from existing circuits or change the panel they are connected to
Modifying Circuit Paths & Wires
Revit creates circuit paths automatically, typically measuring the orthogonal distance from the panel to the farthest device on the circuit. But for fire alarm design, measuring the circuit path along each device is critical to getting accurate lengths when using Revit's length calculations. Adjusting the circuit path is particularly important for class A circuits, as Revit does not have a built-in way to define a redundant path.
Additionally, Revit allows you to draw wires on plan views. While this functionality is less important when using base Revit for fire alarm design—often design firms will instead use Revit conduits, detail lines, or nothing at all—these drawn wires are what FireBIM uses to make its own length calculations and determine how devices are ordered on the circuit. Visit the Draw Wires for Circuits on Plan Views section for more information.
You will need to know:
- How to manually adjust Revit's circuit path
- How to draw wires for circuits on plan views, which will affect various FireBIM calculations and the riser diagram layout
Project Units
The units of measurement for things like length and electric current are configured in the Revit Project Units command. In many cases, the units expected in FireBIM commands will correspond to those in the project; for example, if the Revit project is set to use amps for current, you will need to specify the standby and alarm loads for devices in amps. This applies to families as well.
The way numerical values are displayed in annotation tags is also determined by the Revit Project Units command; for example, if the Revit project is set to round wattage to the nearest watt, tags for a 1/4W speaker will display zero unless you modify the settings to display digits past the decimal.
You will need to know how to view (and modify, when needed) the units of measurement in your Revit projects and families.