Calculating cable lengths

The Calculate Cable Lengths command verifies the cable network connections and calculates the lengths of the circuits/cables in the network, including Spotlight cables. It determines the beginning and ending points of circuits across the cable network, based on connectivity from the schematic and the equipment associations from drop points (including 3D racks). It assigns circuits to each segment of the cable network so that it can display each circuit's cable length.

When Auto is selected for the Cable Length in the Object Info palette of a selected circuit, the Calculated Cable Length is estimated automatically. Use this command to enter values to account for expected extra cable lengths that are needed to place circuits into a rack.

If circuits were assigned to cable objects by selecting them according to the Cable Run ID, the cable path segment will already have been updated by the cable. These circuits are skipped. 

The command identifies and flags errors, such as missing sockets, unassigned drop points, and missing, unassigned, or duplicate equipment items. 

To estimate circuit lengths automatically:

To calculate the length of only selected cables, select the cables (or circuits).

Select the command.

The Cable Length Options dialog box opens. Enter the allowances to account for extra cable lengths needed in a rack, and determine whether to calculate all cables or only selected ones.

Click to show/hide the parameters.Click to show/hide the parameters.

Click OK to calculate estimated circuit lengths in the current layer, accounting for extra cable needed as indicated. In the Object Info palette of a circuit or a Spotlight cable object, the calculated cable length displays. The length can be reported in a cable report, with an estimate of the required lengths of cable for the entire project.

If an error occurred, some circuits may not have been properly identified for the calculation. The circuits are highlighted for identification and correction.

ConnectCAD circuit length calculations

In ConnectCAD, circuit length calculations can occur in a variety of ways.

You can manually select the length from the circuit's Object Info palette; this is useful when you are using standard length cables.

You can specify a physical path for the circuit. Draw a Spotlight cable object on the floor plan and provide a Cable Run ID. Then, select any circuits that should use that path; in the Object Info palette, select the Cable Run ID from the Cable parameter. The circuit length is then set to the length of the cable path.

Alternatively, use the Calculate Cable Lengths command. The devices at the ends of each circuit have a corresponding equipment item with the same name. ConnectCAD checks where these equipment items are located in the drawing and, if possible, estimates the cable length between them. (If you have already set the length for a circuit manually or by assigning it to a physical cable, then Calculate Cable Lengths won’t override that.) 

Several situations affect the Calculate Cable Lengths command calculations.

When the start and end equipment items are installed in racks

If the equipment items are in the same rack, it's simple; the cable length is the difference in height between the equipment items, plus the slack required to reach the equipment (specified in the Cable Length Options dialog box).

If they're in different racks, but in a group of racks placed next to each other, the cable length is the specified slack plus the sum of the two heights, plus the horizontal distance (a multiple of the rack width), plus any allowance for going down into the floor and back up.

Racks are considered to be in a group when there are only 2D racks and they are adjacent to each other; if 3D racks exist, the position of the 2D racks is ignored, and the location of the 3D racks determines if the racks are a group.

If the 3D racks are not in groups, connect them with cable paths so that the Calculate Cable Lengths command can proceed. 

When the start and end equipment items are not installed in racks

ConnectCAD does not know the path a cable might take. Therefore, you have to create a cable path network, place your equipment items in their physical locations and assign them to drop points on the network. With this information, the Calculate Cable Lengths command can find the shortest path through the network and set that as the length of the circuit.

Creating circuits

Editing circuits

Creating ConnectCAD reports