I bought a house from the early 80s and I'm trying to figure out how much amps I can use safely, if it is possible to add air conditioning on the current electric system, and in general if the current situation is safe.

There is one main panel (first picture) and a "kind of panel" in the garage (second picture).

Main power panel

From what I understand, the left thing is the main switch and is rated 80 Amps.

Does that means that this is the maximum that can be used at the same time?

I assume the two residual current device on the right are protecting the light and power point breakers with the green labels, but since all the green label breakers adds to 80 Amps, where does the extra 80 amps of the 3 red label breakers (garage 32A, stove 32A, solar HWS 16A) come from?

Does it means I'm pulling 160 Amps from a 80 Amps main switch? (if that's the case, is it safe?).

Garage Panel

Here I think there is a residual current device for 40A and 3 fuses. I assume those are connected to the Garage breaker in the main panel (which is 32A, not 40. Is this safe too?)

What I'd like to know is:

  • First, is this setup safe?
  • How much amps can I pull from each power point (this is an issue since there are only 2 of them in most rooms, and I suspect they are both wired together since they are always next to each other)
  • On the garage "panel", the marking says 8A for lights and 16A for each power point, but the installed fuses lists the opposite; should I switch them?
  • We are looking into adding Air Conditioning, and the installer recommends installing 7 split systems, each of them requiring its own breaker (5 need 10A, 2 need 20A). That's 90 extra amps. Can this be added into this installation? and if it cannot what would be the best option?

Not sure if it helps, but we are in Australia (240V, 50Hz).

1 Answer 1


is this setup safe?

A fault in your garage lighting might start a fire in the 8A wiring before the 16A fuse blows. Don't replace your fluorescent tubes with a huge bank of film-studio incandescent lighting.

I see nothing else to suggest it is unsafe.

How much amps can I pull from each power point

From any one power point, you can pull the maximum current that point is rated for (e.g. on a UK ring circuit I can pull 13A from any single power point)

However the total load on the circuit is determined by the circuit breaker rating for the circuit. It is perfectly normal to have ten 13A power points on a 32A circuit. Obviously you can't boil ten kettles at once.

You might have radial circuits (I'm not sure what is normal in Oz) and different numbers - but the same principles apply.

Does it means I'm pulling 160 Amps from a 80 Amps main switch?

No, it means that the design used in all household electrical installations assumes that you wont fit every light socket with the most powerful bulb you can buy, plug a full kettle into every power point and turn them all on while simultaneously having a power-shower, roasting a turkey, frying four pancakes, mowing the lawn, drilling and sawing 2x4s, running AC at full, with TV, DVD, Blu-Ray, VHS, HiFi, bedside radio, and all lights on full blast. It might seem like your suburban neighbours do this but they don't really.

On the garage "panel" ...

I would try switching them to see what happens. Inspect them first, maybe the fuse wire used doesn't match the number on the outside.

90 extra amps

You say your main panel has a main switch rated for 80 Amps. It sounds like you need a 200A supply.


  • Buy a power meter - the sort that clamps around your main power cable and tells you how many amps you are pulling. My electric co gave me one free.

  • Get whoever's installing the AC to specify total current that is needed at any one time.

  • Contact your electricity supply company / utility to get supply to house uprated accordingly.

  • Hire an electrician to replace your existing main panel with a new main panel with capacity for another 8 circuits (if that is really what is needed).

  • Get an extra job to pay for the electricity bills.

  • 1
    Red you forgot to add AC and furnace running at same time LOL. I would pull the fuse in the garrage to verify if the lights go out then check the wire size compared to fuse size, having two large fuse is bad news for wiring all over the world.
    – Ed Beal
    Commented Nov 18, 2015 at 14:02
  • Thanks for the very complete answer! If I understand everything will work fine until I'm pulling more than 80A, but it's possible that the main switch will trip while no other breakers will. The sum of rated "running current" for the AC systems is 38A. That's almost half the house capacity so I'll definitely contact a registered electrician.
    – LeFauve
    Commented Nov 19, 2015 at 22:08
  • @EdBeal I pulled the fuses and they do what they advertise ("lights" cuts lights and the two others cut the power points). However, the wire size is suspiciously similar for the 16A and 8A fuses... Can I just buy the right kind of wire and rewire them so I know they will have the correct specifications?
    – LeFauve
    Commented Nov 19, 2015 at 22:12

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