Calculators
NZ-focused planning calculators for licensed electrical and HVAC professionals. Free, no login required.
Electrical
Mains & Submain Cable Selection
Find the smallest compliant cable for consumer mains or a submain.
Voltage Drop
Check any cable run's volt drop against the allowance you set.
New
Total Volt Drop
Point of supply to load, checked against one 5% limit.
Earth Fault Loop Impedance
Check measured Zs against the maximum allowed for your breaker.
Ohm's Law
V, A, Ω, W: enter any two, get the other two instantly.
Three-Phase Converter
Convert kW, kVA and amps between single and three phase.
Maximum Demand
Work out maximum demand for a house or small commercial job.
HVAC
Solar
Solar String Sizing & DC:AC Ratio
Panels per string for your inverter, then the array layout and DC:AC ratio.
New
Solar DC Voltage Drop
Check PV d.c. cable volt drop against the AS/NZS 5033 limit.
New
DC Isolator & Fuse Rating
String fuse, cable and d.c. isolator ratings for a PV array.
New
AC Voltage Rise
Inverter to point of supply, checked against the AS/NZS 4777.1 2% limit.
For guidance only. These calculators are planning aids for licensed electrical workers and inspectors. All results must be independently verified against the current editions of AS/NZS 3000:2018, AS/NZS 3008.1.2, and other applicable standards before being relied on for any installation. CertMate accepts no responsibility or liability for any work carried out, decisions made, or certification issued in reliance on these results. The certifying electrical worker remains solely responsible for compliance with the Electricity (Safety) Regulations 2010 and all applicable New Zealand law.