Perform load calculations

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In this video, we will cover specifying load classifications and defining demand factors.

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In order for a component to be added to a circuit, the component must have an electrical connector.

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Electrical connectors have several parameters that must be defined in order for Revit to properly calculate loads.

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There are also several electrical settings that affect the way Revit calculates loads.

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We'll take a look at how this works.

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On the systems ribbon in the electrical panel, click the dialog box launcher to open the electrical settings dialog,

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and then switch to the load calculations options.

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There are two options for the apparent load calculation method.

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Some true load and reactive load and some apparent load.

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Revit defines the true load as the actual power used by the circuit and the apparent load is the real and reactive power used by the circuit.

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You can select the option that works best for you and that method will be used for the entire project.

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You can also create load classifications and demand factors,

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in the load calculations options, click Load Classifications to open the load classifications dialogue.

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Here, you can see the load classification types that have been created in the project.

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When you select a type, you can see the name and abbreviation of what has been added, the demand factor and then the load class for use with spaces.

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The important thing here is the demand factor.

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When you expand the drop down, you can select one of the demand factors that have been created in the project.

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You can also create new load classification types to meet the needs of your project.

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I'll click Cancel and then click Demand Factors.

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In the demand factors dialogue, you can see all the demand factor types.

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Let's take a look at how demand factors are defined.

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I'll click new and then accept the default name and click OK.

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When defining demand factors, there are three calculation methods that you can use, constant by quantity and by load.

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With constant selected you can then specify the constant demand factor.

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You can also choose to add an additional load to the calculated result.

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When you select by quantity, there are then two calculation options, total at 1 percentage and incrementally for each range.

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You can also see an example below that.

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And take note that the example does not correspond to what's been defined in the table.

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The table is what you use to define the demand factor.

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Let's take a look at how this works with total at 1 percentage selected.

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I'll click the plus button two times to add two rows to the table.

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You can then specify the values in the greater than column and the less than or equal to column.

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For example, I'll input five in the first row for less than or equal to

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and then I'll enter 10 in the second row and notice that the greater than column is updating.

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As I'm updating the less than or equal to column.

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It's also important to note that there are two options here, so greater than and then less than or equal to.

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So it's important to keep that equal to in mind.

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For the first row I'll enter 100% for the demand factor and the second row I'll enter 65% and then the third row I'll enter 50.

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And so what we've done here is actually set up a table that will work for the example that's noted here,

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and so if there are two items then all the loads will be calculated at 100%, and so two items is less than five, so our demand factor is 100%.

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And then if 10 items are used, so in this case our second row here is greater than five and then less than or equal to 10.

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And so if 10 items are used than the demand factor will be 65%.

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So in other words, depending on the number of items, it'll fall into one of these rows and then that demand factor will be used for all loads.

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So that's the important thing to note with total at 1percentage.

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When you select incrementally for each range, then it changes.

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And instead of being instead of a demand factor being used for all the loads, it will work incrementally.

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And so if we have between zero and five, those first five will use a 100%,

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and then between 6 and 10, those items will use 65% and then 11 or more will use 50%.

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You'll also note that this example has changed and this does not.

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The example here does not correspond to the table and so what I just explained was based off of the table that we created for the first example.

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So don't worry about this example updating.

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It's simply the same one for each option.

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And just to give you an idea of how that works.

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So either total at 1 percentage or incrementally.

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The third calculation method is by load and by load works very similar.

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There is a table that you can use to specify the demand factor and you can either select total at 1 percentage or incrementally for each range.

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And instead of the quantity of items, we're looking at the load as indicated since by the by load calculation method,

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okay, once again, you can add additional rows specify the greater than or the less than or equal to.

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Once again pay attention to the fact that this is less than or equal to.

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So that's a big thing when you're defining these and then with either of these, you can choose to add an additional load to the calculated result.

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I will click cancel to close this dialog and then click cancel to close the electrical settings dialog.

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Lastly, let's take a look at an electrical connector and those are defined in the family.

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So also like the lighting fixture family.

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And then click Edit Family, to open the lighting fixture family in the family editor and then select the electrical connector,

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in the properties palette, you can see the system type and as long as one of the power options are selected, then we have several other options.

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The important parameters I want to point out are the ones that we've just been covering.

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And so the load classification, you can associate that to a family parameter.

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That way you will have a parameter that you can modify in the project.

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And so if the load classification of the connector was not mapped to a load classification parameter for the family,

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then you would not be able to modify that.

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And so if you if you notice that you're updating parameters in the family and it's not affecting your load,

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then it's likely because one of the parameters for the electrical connector is not mapped appropriately.

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You can also see the voltage and the number of poles.

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In this case those parameters are not associated so they will be constant unless they're updated here in the family.

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And then there's an apparent load phase 1, 2 and 3.

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And for this example the Apparent Load Phase 1 is mapped to the apparent load family parameter, and then there's also a power factor parameter.

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And so once again, any of those parameters can be associated to family parameters,

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and then modified in either the family or in the project using that family parameter.

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And so once again, depending on the electrical settings and your electrical connector parameter

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parameters that will determine how Revit calculates the loads in your project.