AmpSize

Construction site supply calculator

Supply, RCD and test rules for a construction site.

AS/NZS 3012Data under review

Inputs

Worked example with the default inputs. The live calculator replaces it when the page loads.

Country
New Zealand
Supply source
An electricity distributor's main
Circuit
A final sub-circuit that starts at the construction switchboard
Exception that applies
None
What you are verifying
Portable gear you carry to the job: tools and appliances, leads, cord extension sets, generators and inverters
The RCD is a portable RCD
Yes
This is hire equipment
No
An arc welder is incorporated into the generating set
No

RCD-based additional protection

Required, 30 mA

Supply clause
AS/NZS 3012:2010 Cl 2.1.1(a)
Protection clause
AS/NZS 3012:2010 Cl 2.4.6.1
Inspection and test interval
3months
RCD push-button test
Connect the portable RCD to the supply socket, then press its test button before you connect equipment. Do this again every day while it is in use
RCD operating time test
3months

This result is a design aid. Verify it against the current standard.

Calculation steps

  1. Supply arrangementAn electricity distributor's mainAS/NZS 3012:2010 Cl 2.1.1(a)
  2. Additional protection requiredYesAS/NZS 3012:2010 Cl 2.4.6.1
  3. Maximum rated residual current30mAAS/NZS 3012:2010 Cl 2.4.6.1
  4. Inspection and test interval3monthsAS/NZS 3012:2010 Table 3
  5. RCD push-button testConnect the portable RCD to the supply socket, then press its test button before you connect equipment. Do this again every day while it is in useAS/NZS 3012:2010 Table 3
  6. RCD operating time test3monthsAS/NZS 3012:2010 Table 3
  7. Socket-outlets on a switchboard10AAS/NZS 3012:2010 Cl 2.3.4
  8. Isolating switch marking height6mmAS/NZS 3012:2010 Cl 2.4.4

Questions

Each answer describes what this tool calculates. The result is a design aid. Verify against the current standard.

What does the construction site supply tool do?

The tool reports the supply arrangements allowed on a site under construction or demolition, the RCD protection for the circuit, and the inspection and test intervals for the equipment. It works to AS/NZS 3012:2010.

What RCD does a construction site need?

Clause 2.4.6.1 protects every final sub-circuit run from the construction switchboard with an RCD of at most 30 mA, tripping on every active conductor and the neutral. Three exceptions apply: mechanical operation at risk, SELV or PELV supply, and a safety isolating transformer.

How often are site RCDs tested?

Plug in a portable RCD, or start the generator or inverter that carries one, then press its test button before you connect equipment. Do this every day it is in use. Press a fixed RCD's test button monthly. Do the operating-time test every 3 months on a portable RCD, every 12 months on a fixed one.

Which supplies are allowed on a site?

Clause 2.1.1 allows an electricity distributor's main, an existing switchboard of the permanent installation, a low voltage generator to AS 2790 installed to AS/NZS 3010, or an inverter to AS/NZS 4763. Isolated winding types supply only a separated circuit.

Does the tool cover insulation resistance for welders?

Yes, but only for arc welders built into generating sets, which is the scope Clause 3.6.4 gives Table 2. Other equipment follows AS/NZS 3760 instead; AmpSize's Test and Tag tool covers those checks.

Clauses and tables this tool reads

Every clause and table, with how each was verified

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