Standards
These are the documents the calculators cite. Each note says what the tool reads from the clause or the table. No text of a standard is reproduced here. AmpSize is a design aid. Verify results against the current standard.
AS/NZS 3000:2018
The wiring rules. AmpSize uses this standard for the checks a circuit has to pass: the current the cable must carry, the voltage drop limit, the earth fault loop impedance, and the maximum demand of the installation.
- AS/NZS 3000:2018 App B Para B5.2.2 Note 2clause
Conductor temperature in the loop
The loop impedance tool follows this note. Conductor resistance rises with temperature, so a design value taken at the operating temperature is higher than a value measured cold. The tool says which basis it used.
- AS/NZS 3000:2018 App C Para C6.2clause
Cables in enclosures
The conduit fill tool uses this clause. It adds the cross-sectional area of every cable in the bundle and compares it with the area inside the conduit. The result is a fill percent and the limit for that cable count.
- AS/NZS 3000:2018 Cl 2.2clause
Maximum demand
The maximum demand tool works to this clause. It adds the demand of each load group to get one current for the installation. That current sets the size of the consumer mains and the main switch.
- AS/NZS 3000:2018 Cl 2.5.3.1clause
Protective device coordination
The cable size tool uses this clause to compare the cable with its protective device. The device rating must sit at or below the derated capacity of the cable. A size that the device cannot protect is rejected.
- AS/NZS 3000:2018 Cl 3.4clause
Current-carrying capacity
The cable size tool works to this clause. It divides the design current by the derating factors for the route. The result is the current the cable must carry in the table, before any factor is applied.
- AS/NZS 3000:2018 Cl 3.6.2clause
Voltage drop limit
The voltage drop tool uses this clause for the limit it tests against. The drop from the point of supply to the load is held inside a percent of the nominal voltage. The cable size tool applies the same limit to each candidate size.
- AS/NZS 3000:2018 Cl 5.7.4clause
Earth fault loop impedance
The loop impedance tool works to this clause. It adds the supply impedance to the resistance of the active and earth conductors. The total must be low enough for the protective device to open in the time the clause allows.
- AS/NZS 2053 heavy-duty conduit (manufacturer data)table
Conduit internal diameters
The conduit fill tool reads the internal diameter of each nominal conduit size.
- AS/NZS 3000:2018 Table 5.1table
Minimum earthing conductor size by active conductor size
The loop impedance and cable size tools read the smallest earthing conductor for the active conductor size. The earth size feeds straight back into the loop impedance sum.
- AS/NZS 3000:2018 Table 8.1table
Maximum earth fault loop impedance multipliers by MCB curve
The loop impedance and cable size tools read the highest loop impedance a circuit may have for its device curve and rating. The measured or calculated Zs is compared with it.
- AS/NZS 3000:2018 Table C1table
Maximum demand, single and multiple domestic installations
The maximum demand tool reads the demand rule for each load group in a domestic installation, for one dwelling or for a block of living units.
- AS/NZS 3000:2018 Table C2table
Maximum demand, non-domestic installations
The maximum demand tool reads the demand rule for each load group in a non-domestic installation.
- AS/NZS 5000 cables (manufacturer data)table
Cable overall diameters
The conduit fill tool reads the overall diameter of each cable, so it can add up the area in the bundle.
AS/NZS 3008.1.2:2017
The cable selection standard for New Zealand. AmpSize uses it for conductor data: current ratings, resistance and reactance, the derating factors for the route, and the short-circuit k factor.
- AS/NZS 3008.1.2:2017 Cl 4.5clause
Voltage drop method
The voltage drop and voltage rise tools use this method. Resistance and reactance are combined at the power factor to give millivolts per amp metre. That figure is then multiplied by the current and the route length.
- AS/NZS 3008.1.2:2017 Cl 5.3clause
Short-circuit performance
The fault rating tool works to this clause. It compares the energy let through by the protective device with the energy the conductor can take. The check uses the fault current, the clearing time and the k factor.
- AS/NZS 3008.1.2:2017 Table 13table
Current-carrying capacity, three- and four-core thermoplastic, copper
The cable size tool reads the current a conductor can carry for its material, insulation, core count and installation method. That figure is the starting point, before any derating.
- AS/NZS 3008.1.2:2017 Table 22, 25(1), 25(2)table
Derating factors for bunched circuits and for groups of buried circuits
The cable size tool reads the factor for circuits that share a route. More circuits together means a lower factor and a larger cable.
- AS/NZS 3008.1.2:2017 Table 27(1), 27(2)table
Rating factors for air and soil ambient temperature
The cable size tool reads the factor for the air or ground temperature on the route. A hot route lowers the current the cable can carry.
- AS/NZS 3008.1.2:2017 Table 28(1), 28(2)table
Rating factors for depth of laying
The cable size tool reads the factor for how deep the cable is buried. It applies only to buried cables.
- AS/NZS 3008.1.2:2017 Table 29table
Rating factors for thermal resistivity of the soil
The cable size tool reads the factor for the thermal resistivity of the soil. It applies only to buried cables.
- AS/NZS 3008.1.2:2017 Table 30, 34, 35table
Reactance at 50 Hz and a.c. resistance at 50 Hz
The voltage drop, voltage rise, loop impedance and cable size tools read conductor resistance and reactance at the operating temperature from this data.
- AS/NZS 3008.1.2:2017 Table 52table
Values of constant K for determination of permissible short-circuit currents
The fault rating and cable size tools read the k factor for the conductor material and insulation. The factor sets how much fault energy the conductor can take.
AS/NZS 4777.1:2016
The grid connection standard for inverter energy systems. AmpSize uses it for the voltage rise limit on the cable from an inverter to the point of supply.
- AS/NZS 4777.1:2016 Cl 3.3clause
Inverter connection voltage rise
The voltage rise tool uses this clause for the limit on an inverter circuit. It measures the rise from the inverter to the point of supply. A rise above the limit means a larger cable or a shorter route.
IEC 60255-151:2009 / IEEE C37.112-2018
The two standards that define inverse-time overcurrent characteristics. AmpSize uses them to plot relay trip curves and to measure the grading margin between relays.
- IEC 60255-151:2009 / IEEE C37.112-2018clause
Inverse-time overcurrent curves
The IDMT tool plots relay curves from these two standards. Each curve name sets three constants. The tool puts those constants into the trip time equation and draws the result against current.
- IEC 60255-151 Table 1 / IEEE C37.112 Table 1table
IDMT overcurrent curve constants
The IDMT tool reads the three constants that shape each named relay curve.
IEEE 1584-2002
The arc flash hazard calculation guide. AmpSize uses its empirical model to estimate incident energy, the arc flash boundary and a PPE category.
- IEEE 1584-2002 Cl 5clause
Arc flash incident energy
The arc flash tool uses this model. It estimates the arcing current, then the incident energy at the working distance, then the arc flash boundary. The energy sets the PPE category the tool reports.
- IEEE 1584-2002 Cl 5.2–5.6table
Arc flash incident energy model coefficients
The arc flash tool reads the coefficients for the arcing current and incident energy equations.
Electricity (Safety) Regulations 2010
The New Zealand regulations that sit above the wiring rules. AmpSize uses one threshold from them, to flag when an installation needs a certified design rather than a prescriptive one.
- Electricity (Safety) Regulations 2010 reg 59clause
Part 1 and Part 2 designs
The maximum demand tool watches this threshold. A demand above it takes the installation out of Part 2 of the standard. The tool raises a note so the designer knows a certified Part 1 design is needed.