Hi Reader

I am just letting you know.

I added two options to optimise the earth cable sizing for high current installations in the Cable Size Calculator.

Option: Ignore table 5.1 sizes

Ignore earth sizes specified in Table 5.1 in AS/NZS 3000.

Earth size will be based on fault current and loop impedance only.

This option is available when:

• Parallel single-core cable groups are used.
• ​Check fault rating and Check loop impedance are enabled.
• The calculated earth size is ≥ 120 mm² (copper) or ≥ 240 mm² (aluminium).

More information: Earth sizing rules and Ignore table 5.1 sizes.​

Option: Combined earth fault rating.

The fault rating of the earth cables is based on an equal split of fault current across the parallel earth cables.

This means each earth cable only needs to be rated for half of the prospective fault current.

This option is only available when:

• Parallel single-core cable groups are used.
• Parallel earth cables are used.
• ​Check fault rating and Check loop impedance are enabled.
• The calculated earth size is ≥ 120 mm² (copper) or ≥ 240 mm² (aluminium).

More information: Earth sizing rules and Combined earth fault rating.​

Important: To ensure safety, the parallel earth cables must be the same length, follow the same route, be mechanically protected, insulated, and separated from the live cables to prevent direct faults between phase and earth cables. A risk assessment is required.

Images

Click here to try.

Please let me know if you have any questions or suggestions.

I appreciate your feedback.

Adam van Staden
​LinkedIn Profile​
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This information does not constitute legal, professional or commercial advice. JCalc Pty Ltd gives no guarantees, undertakings or warranties in this regard, and does not accept any legal liability or responsibility for the content or the accuracy of the information so provided, or, for any loss or damage caused arising directly or indirectly in connection with reliance on the use of such information.