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Kitchen Equipment and Aluminum Wires

Monday, February 1st, 2010

Last week, a customer requested two features for Design Master Electrical. We took a look at the requests, and decided they were not too difficult to implement. The first, new calculated kitchen loads, will be available in Design Master Electrical 7.3, which is currently in beta. The second, aluminum feeder sizes, is available now for all customers.

Kitchen Equipment

The calculated load for kitchen equipment depends upon the number of pieces of equipment. Previously, Design Master Electrical has limited you to a single diversity value for kitchen equipment. This worked fine if all your kitchen equipment was on a single panel.

If your kitchen equipment is spread out between different panels, this does not work. On the panels with one or two pieces of equipment, you need to use a diversity of 100%. But on the main panel, you can use a diversity of 65% if you have 6 or more pieces of equipment.

We’ve updated Design Master Electrical 7.3 to calculate the diversity correctly. We are adding this change late in the beta process, so we are limited to counting each circuit with a kitchen load on it as a single piece of kitchen equipment. This will undercount your equipment if you have two or more pieces on a single circuit. In a future version, we will update this to count each device on a circuit properly.

This update is available immediately to all of our customers using the Electrical 7.3 beta. Once Electrical 7.3 is released final, it will be available to all customers.

Aluminum Wires

It has always been possible to model aluminum wires in Design Master Electrical. However, the default wire sizing table we provided only included values for copper wire. We have put together a wire sizing table that includes aluminum values for all wire sizes. The table is set up to use copper wires by default. You can manually change the wire size to aluminum when appropriate. The wire sizes without a label are copper. The wire sizes labeled with “AL” are aluminum.

All the wire sizing values are taken from NEC 2005.

The wire sizes are based upon table 310.16. We use the 60 degree C column up to #1, then the 75 degree C column for 1/0 and larger.

The wire areas are taken from table 5 (THHN, THWN, THWN-2) for copper and aluminum. If you want to size your conductors based upon compact aluminum, you will want to adjust the aluminum wire sizes to match the appropriate column in table 5A.

The reactance (X) and resistance (R) values are taken from table 9.

The ground wire sizes are taken from tables 250.66 and 250.122.

To use these wire sizing tables in your projects, download this project. Open the project and look at the wire sizing table using the DM Electrical->Customization->Wire Sizing->Edit Project List.

Use the “DM Electrical->Customization->Wire Sizing->Copy Project List to Master” command to update your master. All newly started projects will include the aluminum wire sizes.

After you have updated your master, use the “DM Electrical->Customization->Wire Sizing->Copy Master List to Project” command to update existing projects.