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CableCalc F.A.Q.

CableCalc isn't allowing me the option of selecting a 3 phase supply. The option is there but greyed out, how do i enable it?
The user defaults define the type of supply available for quick calculations. If you select the 'Set Defaults' button on the right side of the Supply tab, you should be able to set the default supply to 3 phase under the 'System' section. Don't forget to enter an approriate Ze for a 3 phase supply under the 'Voltage' section as well.

I am using CableCalc to calculate a circuit protected by an MCCB but whatever I do the circuit 'fails' on disconnection time and device impedance. It makes no difference what size of cable i use or what circuit protective conductor (cpc) I add to the circuit.
Check that the source impedance ze for the installation is correct. The quoted electricity supply authorities typical maximum impedance values (0.35 ohms) are unlikely to be accurate in situations where an MCCB is used. If you can go to site and measure the Ze then your calculations will be much more accurate. MCCB's are also often equipped with an adjustable magnetic trip setting. Lowering the magnetic trip setting / device multiplier will increase the maximum permitted Zs, however you still need to be sure that you can achieve discrimination with up and downstream devices.

How many cpc's can I include in a calculation when sizing a cable?
If the cable has a sheath or armouring then that may be used for the calculation together with options for using an internal core and/or a separate earthwire (either automatically sized or selected). Trunking or conduit can also be selected as a CPC when appropriate.

What happens if the maximum size of cable is exceeded when I am trying to calculate a cable size?
The program will attempt to meet the criteria for the calculation by selecting 2 cables in parallel, If this fails it will try it with 3 cables in parallel and so on up to a maximum of 20 cables.

I have designed a project with twelve distribution boards feeding more than 300 circuits and now the architects have repositioned the main transformer. This has completely changed all of the main incoming figures, voltage, Ze, etc.
Simply input the revised source details and then click on the 'Calculate all' button. The whole system will be recalculated using the updated supply figures, and within a few minutes all of the circuits in the project will have been recalculated.