Why did the power go off??!!

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kiwifidget

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#323671 31-Dec-2025 20:45

Monday was a windy day, and at some point one of those fusey things in the switchboard tripped.

No power to parts of the house as we would expect, and we flipped it back up and all was good.

The solar panels were blazing, feeding the house, the battery (Powerwall3), and the grid.

Lots of power outages that day, but not in our area.

Yesterday was less windy, and about 11:30am the power went out to the whole house for about 4-5 seconds and then came back on by itself before we could even say "what, not again!".

What I dont get this time around was that it was very sunny at the time.

Again, the solar panels were blazing, feeding the house, the battery, and the grid.

This time though the grid was out, and remained so for over an hour, but we were ok after the initial teeny outage.

Given that we were not taking power from the grid at the time, and indeed were supplying it, why would we have an outage at all?

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#3448529 31-Dec-2025 20:57

Monday was a windy day, and at some point one of those fusey things in the switchboard tripped.

No power to parts of the house as we would expect, and we flipped it back up and all was good.

Pic of exact device that tripped? The markings on them indicate why it will trip.

Yesterday was less windy, and about 11:30am the power went out to the whole house for about 4-5 seconds and then came back on by itself before we could even say "what, not again!".

What I dont get this time around was that it was very sunny at the time.

Again, the solar panels were blazing, feeding the house, the battery, and the grid.

This time though the grid was out, and remained so for over an hour, but we were ok after the initial teeny outage.

Given that we were not taking power from the grid at the time, and indeed were supplying it, why would we have an outage at all?

It sounds like you were generating in grid-tied mode, the grid failed, so the inverter separated you from the grid and moved to islanded mode?

Generating into the grid doesn't necessarily mean that you're not reliant on the grid for stability. Transfer time might depend on the system, especially if the grid loss wasn't a clean break.

rhy7s

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#3448535 31-Dec-2025 21:21

The switchover time of many inverter and battery combinations isn't instantaneous:

https://skyenergy.com.au/all-about-blackout-protection/

kiwifidget

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#3448536 31-Dec-2025 21:26

@someonesomewhere

This one. It is not unusual for it to trip.

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SomeoneSomewhere

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#3448537 31-Dec-2025 21:29

That's an RCD, likely protecting the five circuits to the left.

Likely a faulty appliance or an outside light full of water.

Also, it looks like you have three phase supply but only a single phase inverter with potentially limited backup supply.

kiwifidget

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#3448539 31-Dec-2025 21:49

yes, we were 3 phase.

The solar installers merged 2 phases into one for the solar, and left one phase (with only the oven on it) off it.

Dont ask me why, thats just how it had to be.

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kiwifidget

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#3448541 31-Dec-2025 21:52

rhy7s:

The switchover time of many inverter and battery combinations isn't instantaneous:

https://skyenergy.com.au/all-about-blackout-protection/

I vaguely recall now the solar installers telling me I should keep the UPSes on all the computers.

That will be why.

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#3448543 31-Dec-2025 22:00

kiwifidget:

This one. It is not unusual for it to trip.

RCDs tripping is far from normal. Suggest you work out what is causing it to trip so frequently.

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#3448557 1-Jan-2026 07:08

mentalinc:

RCDs tripping is far from normal. Suggest you work out what is causing it to trip so frequently.

Yep. Our most recent one was difficult to track down but turned out to be the bathroom fan / light unit, but only in really cold weather.

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#3448565 1-Jan-2026 08:56

The RCD is protecting the three 20A circuit breakers to the left of it. Pretty sure an RCD can only supply a maximum of three circuit breakers in NZ.

The next two circuit breakers are 10A for the lighting circuits and don't need RCD protection.

The labels are too far to the left and not directly under the corresponding circuit breakers, so a little confusing.

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#3448566 1-Jan-2026 08:57

k1w1k1d:

The RCD is protecting the three 20A circuit breakers to the left of it. Pretty sure an RCD can only supply a maximum of three circuit breakers in NZ.

The next two circuit breakers are 10A for the lighting circuits and don't need RCD protection.

The labels are too far to the left and not directly under the corresponding circuit breakers, so a little confusing.

Three circuits per RCD only became a rule under ASNZS3000:2007, which was adopted in I think 2010. Prior to that, you could have any number of circuits per RCD.

Lighting has been required to be RCD protected since I think 2003.

So the RCD will be protecting all five.

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#3448661 1-Jan-2026 14:32

k1w1k1d:

The labels are too far to the left and not directly under the corresponding circuit breakers, so a little confusing.

I see whats happened there now.

The solar people put those 3 new white ones in the middle, and shunted the ones to the right along a bit, putting them out of line with their labels.

Thats annoying.

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kiwifidget

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#3448665 1-Jan-2026 14:48

House was built 2006/2007.

How do you isolate what is causing the trips?

That RCD covers quite a lot of the house.

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mentalinc

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#3448668 1-Jan-2026 14:58

When it trips have a think what was the last appliance you turn on, or is high draw appliance (think toasters, microwave vacuum etc), what lights, fans etc etc.

We had a failing toaster, as soon as it was on for 10 seconds the RCD tripped, replace toaster, problem resolved.

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#3448669 1-Jan-2026 14:58

It's easier if it's fewer circuits. Without that, and without test gear, it's basically pattern recognition.

Rain/wind tend to point to exterior things like lights, outdoor sockets etc. Any buried cables to disused garden lights, outdoor lights that don't work, switches with unknown purpose?

Are there certain appliances that are being used when it trips, or when it hits a certain point in the cycle? E.g. dishwasher pump, sump pump, fridge defrost element.

It's tripping an RCD not the MCB so you're mostly focussing on possible water ingress.

kiwifidget

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#3448675 1-Jan-2026 15:50

What about ants? There must be gazillions of them living in the exterior walls.

Maybe even internal walls.

Thats a whole other problem though.

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