Strange Electricity Usage

myself01

Hi,

I got a Onzo wireless electriity usage monitor a week ago. It is one of the types which just clamps around the mains wire under the meter.

I installed it (as it was plain simple) and it seemed to work fine until today morning when I noticed something strange.

So yesterday night, before going to sleep, it was showing the consumption as between 150watts and 200watts as I had some lights on along with the usual fridge/freezer and tv/sat, etc on standby.

During the day today, even when all the lights were off and the tv/sat were on stanby, and no heating or hot water was being used - the usage kept showing around 500watts.

Then in the evening, around 6PM, it dropped down to under 150 watts - even though I had the lights turned on and the tv was running as well.

Right now, it is showing around 125watts with 2 energy saver bulbs, 1 flouroscent tube, and a normal 6o watts bulb (and I've got the fridge/freezer running with the tv/sat on stanby).

I could not understand why the power usage went to around 500 watts with nearly everything off and dropped down in the evening.

I'm on standard tarriff but the tariff should not matter anyway because the energy monitor is measuring the flow of electricity and not the price.

I will keep an eye tomorrow as well and will post here if it goes up again in the day time.

Any ideas from anyone ???

Thx

myself01

Hi,

Also, I just noticed that when I switch on the florescent tube, the power consumption actually drops by around 50 watts or so !!!

That's not right - is it?

Also, my electricity meter only was two wires under it so I clamped the energy monitor sensor to one of the two.

Does it matter which of the two I clamp it to???

Thx

Mark.TTG

hi
I keep a close eye on my electricity usage, and log the readings manually every day. I have also noticed bizarre things happening.
As you say when I've got hardly anything working on electricity, the reading are abnormally high, yet at other times when lots of electricity is actually being used, it doesnt seem to register it properly. My meter is the latest type only fitted about 18 mth ago, so I doubt its at fault.

penrhyn

The odd readings are due to out of phase loads being recorded by the meter. Energy monitors are very inaccurate below around 200 watts or so. Could the 300 watt increase you see be the central heating pump.

molerat

myself01 wrote: »

Hi,

Also, I just noticed that when I switch on the florescent tube, the power consumption actually drops by around 50 watts or so !!!

That's not right - is it?

Also, my electricity meter only was two wires under it so I clamped the energy monitor sensor to one of the two.

Does it matter which of the two I clamp it to???

Thx

It needs to be connected to the live cable on the output side of the meter or it will give weird readings http://tscp.open.ac.uk/t152/docs/T152install/

chris1973

Energy Meters are just novelties, they generally don't accurately track appliances with various degrees of built in power factor correction. These include appliances with motors / compressors in them, or inductive loads such as Fluorescent Tube Ballasts. They also don't track fast switching activities such as pulse fire thermostats or short forward / reverse wash cycles carried out by most washing machines.

So most appliances in the home are either not tracked or mis-tracked, making them completely useless for accurate use or for reference to, regardless of the fact that some here preach them as their god and sit all night with one eye on them and one on Eastenders.

You already have a highly calibrated, precision measuring device in your home, and its free - It's called the Electricity Meter. If you read it on a regular basis you'll know how much you are using on a day / week / fortnightly / monthly basis, in fact as often and how often as you please.

Energy ratings (wattages) can also be found on most appliances and in instruction manuals.