Electrical Systems General Settings

File: CFG_ElectricalSettings

Objectives

1. Understand Revit Electrical settings structure.
2. Learn how to configure a particular setup for a project.
3. Learn what calculations can be performed inside our Electrical project.

Prerequisites

1. User will be using Revit MEP 2015 or more recent.
2. User will be familiar with electrical engineering concepts.

Description 

We’ll go through our electrical project settings, and when we get a full understanding of this then we’ll start loading and connecting elements with circuits.

We can perform several calculations in Revit over electrical systems, but we have to configure them properly in order to obtain valuable results. Some of these calculations are:
Power loads per panel and per load type.
Actual loads per space.
Number of elements connected by a circuit.
Wire sizes
Wire length

To follow this guidelines you should open a new project with the MOD_BIMMasterplan_ELE_Training_Settings_01 template

And go to Systems>ElectricalSettings, or press ES

Procedure

Hidden Line

Once we are inside our Electrical settings dialog box (see above) we find this:

When representing cable trays in a floor plan, sometimes lines pass ones above the others, in order to represent this crosses properly we must configure hidden lines.

Hidden lines settings are especially useful when we are going to represent our cable trays in a one-line type of representation (Coarse), as we can configure the distance of the gap:

Otherwise is better to deactivate the Draw MEP Hidden Lines, because crosses between Two-line elements are already clearly represented.

Be careful. You have to pay attention if you are representing your elements within a floor plan or a ceiling plan.

General and Angles

In Electrical Settings→ General we can configure how Revit’s going to express some information from our systems by default. Naming and conventions. Nothing less nothing more.

In Angles we can configure how Revit is going to create fitting angles when we are modelling. By default we are going to Use any angle, this is because sometimes it could be really frustrating to model some distribution system figures with constraints in angle creation, this decision leaves some angle responsibility in modeller hands, but technically we consider that on site we have versatility enough to achieve almost any angle.

Cable Tray / Conduit Settings

I have decided to tackle this now because it’s also related to graphics! So let’s start.

In cable tray settings we can configure naming and standards conventions for cable trays, and what is more important, Rise and drop symbols for our CT distributions. This is some kind of counterintuitive because Rise and drop is related to the View Range. See image below:

Here we can also define sizes that are used in modelling. Notice that our Cable trays or conduits are disconnected from our wire calculations, so its designer responsibility to maintain coherence. Remember that Single Line matches with Coarse and Two Line with Medium and Fine detail levels.

Wiring

The settings in the wiring table determine how Revit performs wire sizing, and how wires are displayed in plans. We can configure an ambient temperature for our project, this affects directly to correction factors in wire sizing. Gap of wiring crossing is like Hidden Line but for wires (it’s measured with mm in sheet space, so if we change our view’s scale our gap will be affected). The selectable tick mark styles, as shown:

Short

Circle

Hook

Long

Slanted Line: marks ground connectors

But we can load one created by ourselves as an Annotation family:

In wire sizes we can, for instance, create an iron material with  and delete it with , it has to be based in an existent one. Each size shows ampacity, AWG (American Wire Gauge) size, and diameter of wires available in a project. Revit calculates the wire size for circuits (based on the current rating of the circuit) to maintain a voltage drop of less than 3%. Some insulations are unavailable for different temperatures. You can also deselect some sizes for calculation purposes.

Also we can define the correction factor based on ambient temperature, and the ground conductors sizes for particular ampacities.

In Wiring Types some critical fields are these:

Material - If we want other materials we have to create it before in Wire Sizes

Temperature Rating - If we want other temperature we have to create it before in Wire Sizes

Insulation - The same as Material and Temperature

Max Size - This is the maximum conductor size to be used when sizing wires of this type from 14 to 2000 MCM (thousand circular mils). This parameter lets you control when wires start being sized in parallel runs, rather than by simply increasing the wire size until 2000 MCM is reached. Remember...

 1CM = 5.067×10−4 mm²

Neutral Multiplier - The value specified here is used to increase or decrease the calculated size of the neutral conductor, based on a multiplier of the conductor’s size. Neutral Multiplier is applied after the neutral size is calculated, either by sizing the same as the hot conductors or according to unbalanced current.

Neutral Required - If not selected, a neutral will be omitted for balanced loads, but will always be included for unbalanced loads.

Neutral Size - Neutral equals to hot conductor size or, in unbalanced current, it will be calculated with the resultant flow.

Conduit Type - This affects directly to impedance calculations.

Voltage Definitions

We have to define this before specifying distribution systems. These voltage definitions are different in almost every country. We have to define highest and lowest voltage rating for electrical devices and equipment that can be used with a particular voltage definition.

As said, this configuration obviously has to be first than distribution systems.

Distribution Systems

Distribution Systems’ table is where we define distribution systems that are available in your project. We can select if our DS is single-phase or three-phase, in three-phase systems if it’s Wye or Delta. Number of wires (3 or 4 for three-phase, 2 or 3 for single-phase). L-L (phase-phase) Voltage is not applicable for a single-phase, 2-wire system. L-G (phase-ground) is always available.

Load Classifications and Demand Factors

Load classifications have demand factors inside that are applied directly into circuits, so workflow is what follows:

We insert our elements (with a proper configuration of load classifications): lighting fixtures, electrical fixtures and electrical equipment, and, In my project (properly configured) we create a circuit from one element (electrical/lighting fixture), we assign this circuit I’ve created to an electrical equipment (panel/switch boards or transformers directly). We can now add more fixtures to the circuit. My demand factor is applied to all circuit elements per load classification.

So we have to match properly elements and project load classifications, also demand factors in order to handle simultaneity.

See image below for instructions to configure these project properties:

Window 1:

Window 2:

Summing up

Before start modelling we have to spend some time configuring our project properly. Remember that parameters in our families’ connectors have to match with these settings, so it’s best for these parameters to be actually type/instance Shared Parameters. This is because connectors actually are like “embedded” families inside MEP fixtures or equipment families, so their parameters must be properly mapped in the “host” in order to permit us to manage them in project and avoid editing a family over and over.

We are going to change some of these family parameters in order to fit them into circuits, so my recommendation is: Voltage and Number of poles parameters must be Shared instance parameters and the rest of them must be Shared type parameters:

Why number of poles and Voltage? Because when you connect an element to a circuit for the very first time if these parameters are instance parameters Revit allows you to choose the combination of them. Remember that number of poles are not number of wires, but are related to them. Number of poles are related with circuit protection switches too. See images below:

Unfortunately Revit doesn’t allow us to have 4 pole circuits.

Panel Schedules

Short introduction

So let’s talk about Panels. Managing Revit electrical project data pass through Panel Schedules. They are special schedules and we’re going to see what we can do with them.

Analyze tab >  Panel Schedules

These are the parts of a Panel Schedule:

As every schedule in Revit, it is a view, so we can just drag and drop them into a sheet from the project browser.

Settings

You can only create a Panel schedule if your Panel is connected to a distribution system.

Remember that only if you have Voltage and Number of Poles as instance parameters in the panel when you connect your “power on” your panel Revit lets you choose a combination of these parameters to obtain desired Distribution System.

Canonical workflow in Electrical projects should go as follows:

1. Set up load classifications.
2. Set up demand factors.
3. Assign demand factors to load classifications.
4. Assign load classification to family connectors or directly to families.
5. Assign distribution systems to equipment.
6. Connect fixtures to equipment.
7. Format the panel schedule templates.
8. Create panel schedules.
9. View panel schedules.
10. Manage loads and circuits on panels.
11. Wiring documentation

Created Panel Schedule is different from Power and Data circuits. Everything is Data connected if its not Power.

And in power connected equipments you can create Branch Panel Schedules (only with panelboards) or Switchboards (only with switchboard subcategory):

And in branch panels there are 3 possible configurations:

Two Columns, circuits across; Two Columns, circuits down; One Column.

Here in our Panel Schedule we can change circuit numbers! We can move them up or down and assign spares or spaces to circuit rows. Spares are locked by default, but can be unlocked. Locked spares do not move from their current slot or phase when you rebalance the panel schedule.

One thing we have to know is the relationship between electrical equipment parameter of “Max #1 pole breakers” and Panel Schedule. If we have a max number of pole breakers defined we’ll not be able to drop down a circuit indefinitely, it will always reach our max number of pole breakers… So if for some reason we want to go down and down in our schedule for obtaining a desired number of circuits, first of all we have to ask if our procedure for circuit numbering is correct, and then go to our panel and change this parameter, which is always an instance parameter. If need to show more rows and more circuits we have to edit our panel schedule.

This is related to Panel Schedule template, so let’s have a look inside them!

Templates

For managing how information is displayed in Panel Schedules we have to go to our Panel Schedule Templates in Manage tab.

Here you can do 2 main things: To Manage Templates and to Edit Templates.

Manage Templates

Here we can make 2 important things:

First of all managing templates, second applying them. When managing we can copy, rename and so, but most important is that here we can access to editing too:

Edit a Template

We can edit every single parameter that we have in our project related to electrical circuits:

When editing we can also set some fundamentals for our Panel Schedule about, formatting mainly, with set template options.

When changing a pre existing template we have to refresh it with this tool, located at Modify Panel Schedule tab→ Template panel→ Change Template:

We have to pay special attention to refreshing when managing panel schedule templates, for exajmple for updating Circuit names and Rebalancing loads.

Tips&Tricks

• Try to configure general settings once. Do a template file.
• Be tidy in Electrical Systems modelling. They are rigid, so if you detect a setting failure, don’t procrastinate it.

Conclusion

In this guideline we have learnt how to configure properly our project electrical settings, but without properly electrical parameters family's configuration is unuseful. So let’s learn how to configure electrical families on the Guide OPE_ElectricalFamilies

Associated Files

MOD_BIMMasterplan_ELE_Training_Settings_01 (Template)