Dishwasher stopped - main voltage low

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Lizard1977

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#315338 4-Jul-2024 21:35

My dishwasher just stopped in the middle of a cycle and gave me the error message "main voltage low". The manual says to consult an electrician, which I will do tomorrow. But I've noticed some other weird stuff lately. The lights in the kitchen tend to dim in the evening (from about 5pm) - not every night, but more than just occasionally. Sometimes they will have a faint flicker (they're LED smart bulbs). I also noticed the same kind of flicker in the toilet light bulb (same type of bulb). The other funky thing is that I discovered about a year ago that if I was boiling the jug, running the dishwasher and turned on the tumble dryer (which is in the laundry in a separate room), then it would trigger the fuse in the switchbox. I assumed they were on the same circuit and were just drawing too much at the same time.

I'm going to call an electrician to come and take a look, but I was wondering if any of the brain boxes here had a theory about what is going on. For reference, the house was built in 1966.

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#3256425 4-Jul-2024 21:38

Power issue outside somewhere?
Had a power cut recently. My house was fine. Next door - could watch TV but not boil a kettle.
Turns out a power line was stuffed and after a brief full outage a little later so a crew could do their thing, all was well.

EDIT: Not all power outages cut power off altogether.

richms

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#3256428 4-Jul-2024 21:45

Call power company now, turn off all motorized appliances if you have no way to measure the voltage. Low voltage will kill induction motors if you try to use them.

See if you still have any incandescent lights around and see how dim and yellow they are.

Low voltage can indicate that there is a problem with the neutral connection, meaning that current is going back by the ground peg and the actual ground which has resistance. Also water pipes etc that are bonded to it. This is a safety concern if happening. As its been an ongoing thing since before this evening, there is a good chance that the ground is taking the current and drying out from the heat it creates making it worse and worse. Eventually it will go high enough resistance that you will have a dangerous voltage on things that are connected to it and no loads will be working so you think the power is off, when its not.

I had an issue with a dodgey one here ages back which came right when they replaced a pole and fixed the connection and they were really angry that I never called in the low voltage problems as it is something their faults crew take very very seriously.

Richard rich.ms

steve2222

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#3256520 5-Jul-2024 09:09

If you happen to use a UPS device for back up power for your router/ONT or the like, then have a look at the voltage reading on the front (assuming it displays that).

My wife kept complaing that some of our lights appeared to be dimmer than normal in the evenings ( I did not particulary notice it). Around the same time we had been experiencing the frequent failure of a particular size/type of LED bulb which I put down to Ali Express sourced.

One day, when the wife kept on at me, I thought to look at the UPS display and it was reading 170v!!!

Vector (our line company) turned up pronto (late Friday evening). I thought it might be a corroding fuse on the pole, but they said that was fine. After some playing around they switched our line over to the other phase on the pole and that restoted us to 240v. They basically said the phase was overloaded (too many other house comnections on that one phase).

Vector guys were impressed that I knew what our voltage was, so I showed them the UPS device which was remarkably accurate compared to their official voltage meters.

But the Vector guys also said that even the new phase they connected us to was not much better capacity wise, so they said if they had not got us 240v that evening they would have called base for a new transformer to give greater capacity to the dwellings on our feed - and they would have done it that night!

Lizard1977

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#3256529 5-Jul-2024 09:49

Thanks for that advice everyone. I've rung Powerco and am waiting for a callback.

Scott3

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#3256535 5-Jul-2024 10:20

You are best to assume this is a major issue.

Voltage in the grid & local lines is closely managed, so getting low voltage faults from appliances is a sign something is wrong.

You can get one of these if you want to measure the voltage yourself:

www.bunnings.co.nz/arlec-energy-cost-electrical-meter_p4410270?

As others have said, you need to be very careful until this is resolved.

Low voltage can overheat and damage induction motors.

There is also a risk that this is a missing neutral. A potentially dangerous situation that I don't know enough about to explain. This one has the risk of electric shocks from surfaces that should be earthed, and and has the potential unpredictable and appliance damaging voltage swings.

An electrician would easily be able to diagnose.

Lizard1977

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#3256587 5-Jul-2024 12:18

Thanks. What kind of appliances would have induction motors?

johno1234

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#3256596 5-Jul-2024 12:57

Scott3:

You can get one of these if you want to measure the voltage yourself:

www.bunnings.co.nz/arlec-energy-cost-electrical-meter_p4410270?

I will send that link to my daughter in Dunedin. Her student flat worries a lot about energy costs for heaters, yet they are miserly about running their heatpump. I'm trying to convince her to leave the heatpump on and avoid the heaters in the bedrooms.

Scott3:

As others have said, you need to be very careful until this is resolved.

Low voltage can overheat and damage induction motors.

There is also a risk that this is a missing neutral. A potentially dangerous situation that I don't know enough about to explain. This one has the risk of electric shocks from surfaces that should be earthed, and and has the potential unpredictable and appliance damaging voltage swings.

An electrician would easily be able to diagnose.

If the neutral wire is broken or failed then would power circuits complete to ground instead and that make grounded items dangerous?

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johno1234

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#3256597 5-Jul-2024 12:59

Lizard1977:

Thanks. What kind of appliances would have induction motors?

Some refrigerators, dishwashers, clothes dryers and washers.

nova

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#3256605 5-Jul-2024 13:18

Lizard1977:

The other funky thing is that I discovered about a year ago that if I was boiling the jug, running the dishwasher and turned on the tumble dryer (which is in the laundry in a separate room), then it would trigger the fuse in the switchbox. I assumed they were on the same circuit and were just drawing too much at the same time.

This is probably unrelated to your recent problem, and I think you've correctly diagnosed this, you were just drawing too much power on the same circuit at the time. And your current problem is likely a problem with the neutral connection, as others have described.

neb

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#3256617 5-Jul-2024 13:47

Vaguely related, I have a Modbus power monitor, one of these, that I got to warn me of exactly this issue. Easy enough to interface to an Arduino as per the link, or any similar sort of device. If you, or anyone else, can use it it's yours, although I'd prefer pickup so I don't have to faff around with couriers.

Oh, and a proper geek who did the dishwasher firmware would have had it display "Main bus undervolt".

richms

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#3256642 5-Jul-2024 14:09

johno1234:

If the neutral wire is broken or failed then would power circuits complete to ground instead and that make grounded items dangerous?

Yes, worst if you are in contact with real ground and touching a device that is plugged into the electrical earth. This is one of the concerns with EV charging which is why they have crazy safety needs in countries with general junk electrical grids. Car could be floating at many volts over the ground beside the car and people get zapped when touching it even if the EVSE is not supplying the car.

I would not recommend opening the outdoor meterboc while this is happening as the box is on electrical earth and you're standing on real earth

Richard rich.ms

tweake

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#3256645 5-Jul-2024 14:26

Lizard1977:

Thanks. What kind of appliances would have induction motors?

its not just motors.

most electronics do not like running on low voltage. one of my jobs was electronics and appliance repair in a rural town. we used to have a lot of single feed power line runs which would cause low voltage problems, especially around milking time (back when it was mostly once per day). lots of issues, especially with spikes when loads switched on/off. only thing worse was farmers replacing fuses. often the wrong size and also not replacing the spike protection on the boards.

SATTV

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#3256650 5-Jul-2024 14:37

We have the same issue, the body corp has been procrastinating but now we have a new member who has taken on bard to get this fixed.

Some evenings we are down to 190V, when the hot plate turns off and on the lights DIM.

We have had an electrical inspector out and he said it was all OK our end.

I use a Athom Smart Plug V2 but this looks like the latest version https://www.athom.tech/blank-1/esp32-c3-au-plug-for-esphome

I monitor mine via Home Assistant.

Vector is coming to have a look but it is costing us as we are a private complex, I hope the developer put in the correct size cable, we are hoping they will put in a small transformer to keep the voltage more even.

John

I know enough to be dangerous

Lizard1977

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#3256675 5-Jul-2024 16:30

Scott3:
You are best to assume this is a major issue.

Voltage in the grid & local lines is closely managed, so getting low voltage faults from appliances is a sign something is wrong.

You can get one of these if you want to measure the voltage yourself:

www.bunnings.co.nz/arlec-energy-cost-electrical-meter_p4410270?

As others have said, you need to be very careful until this is resolved.

Low voltage can overheat and damage induction motors.

There is also a risk that this is a missing neutral. A potentially dangerous situation that I don't know enough about to explain. This one has the risk of electric shocks from surfaces that should be earthed, and and has the potential unpredictable and appliance damaging voltage swings.

An electrician would easily be able to diagnose.

With that meter from bunnings, how would I use it to check the voltage? Do I just plug it in any wall socket? Or does it have to in line with an appliance that plugs into it? For instance, the dishwasher or the dryer?

richms

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#3256728 5-Jul-2024 16:52

Press FUNC till it displays it. You can see current of the connected load, but without one there is still a voltage and frequency reading that you can cycle thru.

May as well get a smart socket that has a power meter in it for less that is useful in other ways. Voltage should be pretty close to the same thruout the house, and if one place is showing too low for a dishwasher to run and another is fine, you either have 3 phase with a dropped phase, or else a massive problem internally. https://www.bunnings.co.nz/arlec-white-grid-connect-smart-plug-in-socket-with-energy-meter-single-pack_p0273367

Richard rich.ms

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