Breaker size should be what is recommended in the AC manual. Cable size should be as per the Australian Standards (AS 3000 and AS 3008). Typically, 2.5mm2 cable is used for 16-20A circuits, while 4mm2 cable is used for 20-25A circuits.

In the case that the OP did mistakenly write maximum when they meant minimum or nominated, then yes AS3000 would require you to install a 25A circuit breaker and appropriately sized cable in accordance with the manufacturer's instructions.

That is correct. You should have no issues with the cooktop tripping the breaker. IF you did however, and decided to up the cable to 4mm, you can fit a 25A CB on that size now, with the derating. It used to be 32A, but its less now.

If the current carrying capacity of the cable is 25A then it is however fine to also use a CB rated 25A if only a 20A one is fitted.

4mm2 partially surrounded is good for 27amps. so get the circuit breaker changed to 25a rcbo when they install the oven

June 14, 2018 - So whilst we are on the subject of CB ratings I'd like to refer you to table I1 in AS3000 so that you can see the limitations about fitting plug-in CBs into ceramic fuses. If the cable is an old imperial one with V75 insulation (most common in old installation), and it is partially surrounded by thermal insulation, the best you can use is a 10A plug-in breaker not 16A.

We're installing a new induction cooktop, it's a Bosch 90cm unit, PIV975DC1E. It lists a max power requirement of 11.1kW. Our electrician has run new 6mm cabling on a dedicated single phase circuit, however it's only on a 32amp RCBO.

December 10, 2018 - But why 25A on the power circuits? unusual I dont know. House was built about 10 years ago. All the CB's were already installed when i bought the property. ... If the lights are on 16amp breaker then they would be wired in 2.5mm. And power would be 4mm. Pretty sure they won’t be. Also the light circuits should be on different rcds and power circuits spread over both as well. Maximum 3 circuits per rcd or even better to have rcbos on all circuits.

January 2, 2021 - with that cable run 4mm on roughly 20m you should be able to have a 20a/25a rcbo on it, but a sparky will have to assess that. New ac units don't have in-rush current anymore.

Now standard GPO cct is 20 amp HRC fuse or 20 amp c/b on 2.5 sqmm cable. PS Circuit breakers are preferable as they are slow to open on overloads and quick to open on faults ie s/c. With RCD protection the leakage current is usually 30ma for general use and 10ma for hospitals / medical.

March 17, 2023 - I've tried to find A-curve ones, but they are special order at every supplier and more expensive, so have never tried a 25A one to see the result. Would love to know what others have found to work. ... which looking at several offerings inc SE tends to be 100mA trip A curve RCBOs, not the normal 30mA C-curve ones · I think you may be getting your information mixed up. The most common trip "CURVES" are B, C and D which relates to the amount of current required before the MCB/RCBO will trip in an overload condition. While RCD's come in different "TYPES" i.e. A, AC (no longer used in Aus), I, F, B & S and are chosen to match the nature of the installation they are protecting.

May 15, 2016 - Hi, I have a 3 storey, 2 year old residential property in Perth WA, that has 2 x 16a RCBO's protecting 1.5mm2 lighting circuit wiring. The board also has 3 x 20a RCBO's protecting the 2.5mm2 power circuit wiring circuits. My understanding was that 1.5mm2 wiring could only be protected by 10a RCD protection and 16a or 20a protects 2.5mm2 wiring.

The mains fuse meter board was 80A, and the sparky wants to put a 63A MCB on the meter board (at the power pole) and 19m length of 10mm2 2C+E round submain cable (because there is an ground/earth electrode into the soil at the base of the power pole. So on the sub panel in the barn we would have: - a 63A (6kA) MCB - a 32A (6kA) MCB with 10m of 6mm2 2C+E to the 32A captive switched socked for the welder. - a 25A (6kA) MCB with 4mm2 2C+E for the circuit with the 15A sockets for the equipment (drill press, bench grinder, pedestal mounted linisher, air compressor... etc.) - a 20A (4.5kA) RCBO for the already established mixed circuit with a few 10A GPOs and the lights (this was the original 16A (3kA) mixed circuit that was the only circuit in the barn before this work).

June 21, 2015 - Because those smaller conductors are not drawing the load – the RCD shared bus is. Just because they are connected at the main switch doesn't mean they see the same current draw. As the above poster said, the maximum load those conductors are able to draw is 20A as limited by the RCBO.

All of that is irrelevant. It doesn't matter. Yes, you can physically run 3 AC 's on 1 circuit, provided the cable and RCBO is correctly sized. However, technically, you're not allowed to though.

August 26, 2025 - Would have thought those clipsal switches should have also been updated to RCBO Type A's, as my understanding is that a sparkie does any work on the MSB they're required to bring it all up to current codes, not just the switches/rcbo they touch. Reason why my installer flagged needing to replace 2 x 3 pole breakers running 25A for HVAC and 6A for SolarAnalytics.

If that is the case, then only one is allowed on a power circuit that is 20amp with 2.5mm cable. At the very least I reckon you should get rid of the 40A RCD and just use individual RCBO's for each circuit. At least that way, if you do have a leakage problem, it is confined to one circuit.

Looks fine from the pics.....you actually have RCBO's on the Hotplates and Stove as well as (guessing) RCD's for power and lighting Enough room for an additional RCBO for the AC as well. ... Oldrolla writes... Looks fine from the pics.. Thanks i was unsure due to an electrician saying that the switchboard needs upgrading, then went on to say that he needs to get a truck from the electricity company to change the power cable from the pole to the house.

January 13, 2021 - To calculate the current demand ... 4600W divided by 230V = 20 amps. You need circuit wiring and an RCBO (a residual current with overload protection device) both rated for 20 amps....

February 18, 2020 - Then the install is NOT compliant and get them back down. As the installer will then need to install a dedicated feed you will get a RCBO for free for the air-cons as all new circuits need one by law and cannot be grouped on a common RCD across multiple breakers.