Half the house has no power

Look outside before you touch anything

Half a house going dark comes down to one of two things. Either the network has dropped a phase somewhere in the street, or one of your own main switches or incoming phases has let go at the switchboard. Before you start flicking switches, walk out the front and look at the neighbours. If their lights are off too, or the streetlights are out, it is a network fault and Ergon Energy is the call, not us. Nothing at your switchboard will fix it.

If everyone else is fine and it is only your place, open the switchboard and have a look. Note which switches are off and which rooms are dead. On most houses in Craiglie and Port Douglas that is enough for us to know what we are walking into.

One thing to check straight away. If lights in one part of the house are unusually bright, almost glaring, while lights in another part are dim, orange or flickering, turn the main switch off and ring us immediately. That is the pattern of a lost neutral and it can cook appliances while you stand there watching.

Single phase, two phase, three phase, in plain terms

A single phase house has one live conductor coming in and one main switch. If that drops, the whole house goes off, not half of it. Larger homes, and anything with ducted air conditioning, a pool, a bore pump or a big shed, often have two or three phases coming in. Each phase has its own main switch and feeds its own group of circuits. That is why losing one takes out a clean chunk of the house while the rest carries on. Lights working in the kitchen and nothing in the bedrooms is textbook.

What it usually turns out to be

Most often it is a main switch or a safety switch that has tripped on one phase, taking every circuit behind it. Sometimes there is a genuine fault sitting behind it. Sometimes an appliance has failed and dragged the whole phase down with it.

Next most common is the supply itself. Up here the connections at the point of attachment and inside the meter box take a hammering from salt air, and corroded or loose terminations heat up and eventually fail. Wet season water finds its way into meter boxes. Ants, green ants especially, and geckos build up inside enclosures and across terminals, and we pull them out of switchboards constantly. After a blow, a branch through the service mains will do it too.

The dangerous one is a broken or high resistance neutral. The neutral is the shared return path. When it fails on a multi phase supply, the phases start referencing each other through your appliances instead, so voltage climbs on the lightly loaded side and collapses on the other. Televisions, fridges, air conditioner control boards and pool equipment do not survive that for long.

What not to do

Do not sit there resetting a main switch that will not stay on. Each reset re-energises the fault. Do not touch anything on the supply side of the meter or break a seal, that is network property and it is live even with your main switch off. Do not run extension leads from the live half of the house into the dead half, especially not out to a shed or anywhere that gets wet, and never backfeed a generator through a power point. And do not go poking at it with a multimeter from the hardware store. In Queensland, testing is expressly energised electrical work, and that includes locating faults, so it is licensed work whether you find the problem or not.

What we do when we get there

First job is proving which side of the meter the problem is on, because that decides who fixes it. We measure each phase and check neutral integrity under load rather than guessing, then work back through the switchboard, checking terminations for heat and discolouration and splitting circuits to isolate the faulty one. Where a fault comes and goes we can leave a logger on it. If it turns out to be storm damage on your side, the repair has to be tested before the supply goes back on.

We do fault finding every day. It is our single biggest job type. If the switchboard itself is past it, we will tell you plainly what a switchboard upgrade involves before you commit to anything. Emergency callout is available 24 hours, every day. Ring (07) 4099 3497.

Sources: WorkSafe Queensland, testing as energised electrical work; Electrical Safety Office, electrical safety during storms.