Weird voltage in the house

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TheMaskedOnion

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#293843 16-Feb-2022 18:01

Hi,

We have purchased one of those power cost meters that you can just plug in to the power point to measure appliance power consumption. The unit we have is made by Arlec (https://www.bunnings.co.nz/arlec-energy-cost-electrical-meter_p4410270)

I have this unit plugged in with nothing connected and i'm getting these weird readings.

As you can see the voltage is reporting 160v at 44hz or 32hz.

I assume voltages this low should cause havoc with everything electrical in the house?

We do get the occasional flickering\dimming lights in the evening and we can also hear the fan slow down when the lights dim. but things like TVs and computers have no issue.

Would this most likely just be a bad Arlec unit?

EDIT: I have just powered off the Arlec for 10 mins and plugged it in to the same socket and now it's reporting 223v 50hz.

SomeoneSomewhere

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#2869839 16-Feb-2022 18:22

Yeah, faulty or misbehaving meter.

Low or high voltage is possible, but you would also see significant changes in e.g. bulb brightness, fan speeds, hob behaviour etc. 160V is way out of tolerances. If you get actual readings that bad or see lights flashing significantly, call your power company.

Low or high frequency is more-or-less impossible without the entire island being affected unless you're off-grid.

gregmcc

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#2869840 16-Feb-2022 18:22

Dipping lights when other things is indicative of the voltage dropping down as more load comes on, main reason for this is a loose connection, it could be the service fuse the street pillar/overhead pole fuse.

It could be a loose wire in your mains entry box (over head service mains) or a loose wire in your main switch.

It could be that your service mains is too small for the load, without more details like the age and type of wiring in your house it is hard to say.

The frequency should be 50Hz, it may vary by 0.1 hz. I would suggest that the meter is faulty

TheMaskedOnion

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#2869843 16-Feb-2022 18:26

Thanks for the replies.

I should have mentioned that Vector was at our neighbors and i got them to come over and test from our meter out to the street which came up fine.

Can anyone recommend a better quality unit I can replace the Arlec with?

Linux

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#2869849 16-Feb-2022 18:39

Get a good quality multi meter

gzt

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#2869872 16-Feb-2022 20:04

TheMaskedOnion: Can anyone recommend a better quality unit I can replace the Arlec with?

Some varieties have built in batteries or a built in rechargeable. It may have been a problem with first use or a battery. Personally I'd take it back and replace it with the same. Check the manual but it's probably just one faulty item or there's some odd inductive or capacitive load in your house confusing the hell out of it.

gzt

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#2869873 16-Feb-2022 20:07

Linux: Get a good quality multi meter

A multimeter is an expert tool and life threatening to untrained operators. It''s not simple to measure appliance power consumption with a multimeter. And, probably not legal

Dyson

Shop now for Dyson appliances (affiliate link).

neb

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#2869944 16-Feb-2022 21:37

gzt:
Linux: Get a good quality multi meter

A multimeter is an expert tool and life threatening to untrained operators. It''s not simple to measure appliance power consumption with a multimeter. And, probably not legal

Also, while I realise that Linux qualified his suggestion with "a good quality DMM", unless you know what you're looking for a lot of the off-the-shelf ones you'll find locally will be rubbish cheap Chinese-made ones that you certainly don't want to go poking around mains circuitry with.

Or possibly even taking measurements with.

Anyone sprung for a BM786? I've been drooling over the 121GW, not that I care about all the doohickeys but the dual display is nice for "here's your reading, but you should know that something odd is going on too" secondary info.

elpenguino

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#2869958 16-Feb-2022 22:18

TheMaskedOnion:

Hi,

We have purchased one of those power cost meters that you can just plug in to the power point to measure appliance power consumption. The unit we have is made by Arlec (https://www.bunnings.co.nz/arlec-energy-cost-electrical-meter_p4410270)

I have this unit plugged in with nothing connected and i'm getting these weird readings.

Many meters, even good ones, struggle to make sense of the noise when they're not connected to a 'real' thing to measure.

How does it fare with a real load that you can verify? For example, try it with a lamp (50W bulb or whatever) and see what it says.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

nickb800

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#2870018 17-Feb-2022 07:04

If you have a smart meter, then you should be able to cycle through the display menu to see the frequency and voltage, so that's an easy cross-check to see if your plug-in meter is in the ballpark or not. You could also compare the load recorded by the smart meter to that of your plug in meter, if you turn everything off in the house at the switchboard, except for one appliance going through the plug-in meter.

cyril7

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#2870061 17-Feb-2022 08:34

Hi, as others have noted and you have discovered, that device sounds dodgy. As for 44Hz, if that were real then the entire nation would have fallen into darkness almost immediately and Transpower would currently be trying to jump start the network.

An electricty network that spans many generation points creates a concept of the "infinite bus", if there is inadeqate generation compared to load, then all the generation machines (which are all spinning at the same speed and phase unless specific pf correction machines) will begin to slow, and then the frequency will drop. I understand extream limits is +- 0.5Hz and typically +-0.2Hz, much outside of that and if you dont have adequate spinning reserve quickly at hand to lift the frequeny then it all goes turtle.

Cyril

frankv

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#2870134 17-Feb-2022 10:49

I did once find AC 80V on a a dual-switch lighting circuit (with a multimeter). Turned out to be induced... there wouldn't have been any current available to do any harm (although I didn't test this out).

I'm guessing you're seeing something similar with your meter. Hence also the odd frequencies.