500W = 4382KW/year

Anyone ever tested the usage of light dimming modules with lights out?
8 years ago we did build our house and implemented KNX domotics with 15 dimming modules for the lights. Now I end up wit a constant 500W usage in our house. I did elimanate everything..bringing me back to 250-300W usage for the domotics during night. And this is only used for light switching. Not even any touch screen.

Is it really possible that every dimming module consumes 25W even when lights are out? If so... I could drive 10000kms a year with a Tesla for the same KW!

gebhardm's picture

I assume, this is reactive power; can you cross-check with a plug-in power meter?

noelis-it's picture

Hi Gebhardm,

I only have a power meter that fits in a schuko socket. The modules are built in our installation in the garage.
My friend has the same situation therefore he just ordered a flukso to compare.
We both have 7000Kw/h yearly... And we have a similar domotics setup.
Gira switchting modules with Siemens dim modules.


michi's picture

If every dimming module really consumes 25W, it would get noticeably warm. I'd compare measured Flukso consumption with your meter consumption. As Gebhard says, most likely, this is phantom current rather than real consumption.


petur's picture

Even if it is phantom power, it still stinks.

There's a reason I use plain switches at home, all these domotics modules suck a lot of power. I have a limited number of simple Niko dimmer modules (in-wall), and even when the light is off, you can feel the button is slightly warm....

noelis-it's picture

It's still unclear where this comes from.
If the measurement would be wrong - 500W constantly - I'm still doubting why we have a yearly consumption of 6000-7000Kwh?
Most of our lights are LED. We have motion detection sensors in toilets and hall.

When I started to measure from bottom up yesterday... I had 19W. (1th row)
This was caused by the Flukso/internet/router/alarm, all other power was off.

So at that moment it's clear that my measurement was according to reality.
If you see that every 5 minutes I enabled some parts of the house.
The 4th column shows how many Watt's are added in the 5 minutes after enabling that circuit. (sorry is in Flemisch)
Another potential consumer might be the pump from our floor heating.
I need some time to measure it...but I'm a rookie when it's not IT related :-)

tijd aan wattage added?
11:32 alarm,internet,flukso 19
11:40 kelder (alle) --> diepvriezer 100 81
11:45 stc living & keuken 136 36
11:50 koelkast,microgolf,oven,kookplaten,dampkap,vaatwasser 327 191
11:55 stc berging/hall &slaapkamers & droogkast/wasmachine 342 15
12:00 boiler & zolder & buiten/hek & lift 432 90
12:05 zolder 2/ Badkamer 470 38
12:10 licht 618 148
12:15 omvormer 580 -38

michi's picture

I don't read/speak Dutch but, being of German decent, I can decipher at least some of the above… If you are looking at a base load of 500W, 24x7, that makes for 4.3 MWh per year all by itself. So, if you end up with a total of 6-7 MWh per year, that's not at all unreasonable. It depends on the number of people in your house; for three people, 6-7 MWh annual consumption is not unusual.

To me, the best way to reduce your electricity bill is to look at standby load. At Australian pricing, every 10W of 24x7 consumption adds $21 per year. If I'm running at 300W standby, that's $620 a year, which is enough money to make me think about saving some of that. So, take your consumption (plug-in style) meter and hunt down those pesky 24x7 consumers, and think about whether there is a cost-effective option for replacing them with something that draws less current.

The second angle is to look at lighting. It pays to install LED lighting for high-usage areas. Do your return-on-investment calculations. For low-use areas, an energy-efficient light fitting will generally not pay for itself until long after you are dead. But, for high-use areas, you come out ahead after five or six years. And, if you wait another year or two before buying those energy-efficient fittings, you might well come out ahead after four years, because LED bulbs are getting cheaper and better all the time. You get to pick your poison…


gebhardm's picture

OK, let's try to sort this out; Michi gave some great hints already - be aware that the measuring mode of the FLM's clamps does not allow "certified" consumption control; what counts, is the meter's reading - so always take this as a reference; make the test to write up the meter counter value at 18:00 on two days and compare to what the FLM shows (take the MQTT counter values at the same time --> either with the "gauges" or simply with mosquitto on topic "/sensor/+/counter"); if there is a discrepancy, then this is a probable indicator for phantom loads, better "reactive power" (which private households do not have to pay).
1) The always-on-communication stuff w/ FLM and router with around 20W sounds reasonable - I have around the same consumption here.
2) Gira installation - what I quickly found was that this actuator stuff should add around 20W to the base load (given a power supply of 24V DC/700mA; switching is done by zero-crossing, electronic relays, that is TRIACs - no reactive power here (hopefully) - it is somehow strange that Gira does not tell overall consumption of their home automation stuff...) - so, same order of magnitude as the communication (if not added there already)
3) Refridgerators - these mostly are nasty and add 250kWh/a to the bill for a class A-device; we have a combi cooler/freezer that takes around 120W when on - the cooler the more, the longer on here...
4) A stove should only add when on; a built-in clock hopefully is negligible (this is for ANY clock then; but if you have some more of these, also 1-2W will add each)
5) Light adds 148W?! (on or off ???)
6) Pumps - these may also be nasty, especially if always on (like circulation); these add 30W++ - I replaced all of the old 70W+ pumps with new Grundfos Alpha 2 - and this pays out, if you can avoid a plumber and do it yourself. Also I have a temperature controlled circulation that is on only if needed.
Take a look at https://github.com/gebhardm/energyhacks/blob/master/ElektroCamp/Negawatt... - this is what I did; everything else now would be cosmetic.
7) There is still the potential bad power factor in your home, somewhere - but this may only be hunted down by something like the openenergymonitor with appropriate phase monitoring of current and voltage.
So, as Michi suggested, wake the Sherlock Holmes in yourself and first hunt for some more plausibility;

gebhardm's picture

And I forgot - a TV set in stand-by, if not newest generation, may also take a freaking load... (I still don't know why our Toshiba wants 40W when in stand-by; does it "heat" its backlight?!)

fl177's picture

To give you a comparison in phantom load for a 2-family house: ours amounts to 2.9% of our active consumption. Extrapolating that to your 6500 kWh/year would estimate your phantom consumption to be 200 kWh/year (or 22 Watt continuous). it's a very rough comparison offcourse.

We measured our phantom load (reactief vermogen) during the last 6 years: 2388 kVarh phantom load per 82803 kWh active consumption: that's 2.9 % (measured with a Carlo Gavazzi EM-23DIN meter: see http://www.tic.co.th/file_upload/download/20140128025554.pdf).

[We mainly have a few inductive and a few capacitive loads: 2 circulation pumps, a gasoil burner with blower, a class A+ fridge, a few kW (if they're switched on) of TL-lamps , twice 4kW PV-invertors and a few allways-on servers (1000 W continuous).]

Merlion's picture

There seem to be a mix-up of terms here. Phantom Power and Reactive Power are two entirely different things.

- Phantom power is power consumption caused by devices that aren't switched-off entirely, e.g. a TV in stand-by mode waiting for someone to press the remote control or a LED or neon indicator in a socket strip. This power does appear on your utilities bill.

- Reactive power is power represented by the phase shift of current in reactive loads and/or harmonic distortion of the drawn current in non-linear loads. This power flows back and forth from grid to load at the pace of the line frequency and therefore doesn't appear on your utilities bill. This figure also has hardly any relevance in a domestic setting.

noelis-it's picture

Last night I switched of my "not dimmed" circuits.
These are mainly the toilets (motion detected) , garage (1xTL circuit) and the basement. (5xTL circuits.)
This provided me 60-80W less consumption. If I understand it correctly, this would be all mainly reactive power.
Together with the 40-60W from the dimmed circuit it so consumes roughly +100W with LIGHTS OFF.

Yesterday I also tested my GB142 heating power consumption.
Loaded it consumes 112-117W. Off it consumes 9W (phantom power?)

Today I'll probably hook up the freezer again. It's a 3yrs old A++ so I'm not expecting much consumption.
The refrigerator might be worse. It is 8yrs old. But I don't expect it to eat 200W constantly... otherwise I will really replace it.

I might buy a emonpi. But for me, the Flukso does enough by showing me the 520W line by night.
It might be better to buy a clamp meter of hire someone with the skills to measure with a clamp meter.

gebhardm's picture

"Phantom power" I actually know only from powering microphones... So indeed, we should stick to either "real" (which is no phantom if to be paid, even though you might not directly know where it comes from) and "reactive" power - see https://en.wikipedia.org/wiki/AC_power (Tesla's revenge ;-))
In a first step I really would go for a simple comparison of the utility meter and the FLM readings to sort out indicators...

Merlion's picture

"It might be better to buy a clamp meter of hire someone with the skills to measure with a clamp meter."

You'd have the same problem with a clamp meter as it only measures current, regular models don't even measure True-RMS current and generally don't have the dynamic range to measure currents as low as a few mA to let's say 40A unless you switch between clamp and wired connection. The only alternative for a thorough comparison is a professional power meter/analyzer. Such instrument also differentiates between the different quantities:

- Apparent Power (Dutch: Schijnbaar vermogen), unit: Volt-Amperes (VA)
- True, Real or Active Power (Dutch: Actief of werkelijk vermogen) , unit: watt (W)
- Reactive Power, (Dutch: Reactief vermogen) unit: volt-ampere-reactive (var)

You may want to familiarise yourself with this if you want to have a proper understanding of power consumption. Google is your friend. Unfortunately it isn't the easiest of topics, especially power factor caused by harmonic distortion.

Merlion's picture

To help you understand the different quantities in my previous post, you may consider the following experiment.

Disconnect as many loads in your house as possible. Plug a CFL-bulb with known rating (15W for instance) in an available power socket and observe the increase in your Flukso reading. The increase is likely going to be larger than the rating on your bulb.

- The rating on the CFL-bulb is Real Power (W).
- The Flukso reading is Apparent Power (VA)

Fluc's picture

Why not using an din rail kwh meter with pulse output ? This divice measure power (watts) not current (amps) like with current clamps. The latter shows only correct consumption for resistive loads.
We measured in the beginning with a 50 A current clamp and 100w reactive power for the induction stove alone (in the off position of course) was not normal. So i started looking around and on this forum...
Now with an pulse kwh meter, off is off, so no consuption showing on the Flukso dash.

bellyf's picture

Fully agree with Fluc. Before I started using Flukso a year ago I saw all the problems with the clamps and decided to go for din rail meters. I have 2 installed to measure my solar electricity production and it works very well. The meters cost about € 25 and I had them fitted at the same time my solar panels were installed. Connection to Fluksometer is straight forward. I see less than 0.4% difference between the production reported by the Omnik convertor and the din rail meters.
I get my consumption figures from my smart meter so no din rail meter required.

ndupont's picture

My two cents about the kitchen appliances, if you have an induction hob, it probably explains most of the reactive power on that circuit. I have 150 VA with mine, although it only consumes about 2 watts of active energy. The fridge is probably not the guilty one there.

Actually most of the modern equipment is equipped with switching power supplies that have a really bad power factor when idling.
My list includes the induction hob (150), the robotic mower (30), the robotic vacuum cleaner (10), modem, router, nas (40) as well as the hi-fi standby (~20)

michi's picture

In the long run, installing a pulse meter is the way to go. With current clamps, you get a guess-O-meter in most households. There are so many devices around now with a large power factor that current clamp measurements rapidly become useless. All the switching power supplies for routers, phone chargers, etc. Fluorescent lights contribute to that too, as does your fridge, your air conditioner, induction hob, etc. Over time, the number of devices like this keeps going up, because the whole world is changing to switching power supplies whenever possible. (The are cheaper, weigh less, last longer, and are more efficient.)

Before you rush out and get a pulse meter installed, take a reading of your Flukso consumption and a reading of your household meter. Wait two weeks or so, and compare the consumption recorded by each. Your household meter will be dead-accurate, so that will give you a indication of how good/bad your measurements with a current clamp are.