Purchasing correct equipment

Hi All,
I have been searching for a home energy consumption monitor for a while and the majority on the market do not appear to be very good when reading reviews plus I guess the majority are made in China something as off now we should not be doing! I would like to support UK and Ireland manufacturing so as a reasonably savvy bloke would your system for a single phase consumer be suitable for me to install?

1 Like

Welcome & yes (is the very short answer :grinning:).

Just consumption or Solar/Battery/EV charging etc - that will make a bit of difference to your choice. If you are not sure please ask!

Welcome, Ian, to the OEM forum.

Much depends on the detail that you don’t yet know you want, but will at some time in the future.

If all you want is a basic energy monitor that does what you could do with pencil and paper by reading your meter every 10 seconds, 24 hours a day, 7 days a week, and then plotting the graphs by hand, then an emonPi is what you want.

If you need more details - and you can get access to the cables safely, then think about that now, because the emonPi can only measure two circuits (it was designed principally to suit the UK whole-house + PV monitoring requirement).

If you do get an emonPi, then (a major plus point for many people) everything is on your premises and under your control. You’re not dependent on a manufacturer’s website to record and hold your data - then see it evaporate when they go under - or when they start to charge. (But remember, you need to do your own backups - SD cards can fail.)

Think a bit more, come back with any questions.

Hi Brian,

Just looking to record consumption but the ability to be fairly comprehensive once I understand it.



1 Like

Hi Robert,

I am looking for a unit that records in real time and can download to a PC, we are trying to identify why our bills are so expensive, we used to run a small business and the costs were high due to the equipment operating but now retired completely for a year so very little equipment running but the bills very similar?
Does your unit identify individual appliances or is that a bit of a sales pitch?

The emonPi will certainly do that. Actually, it presents the data as a web page on your LAN, so a PC or phone or tablet can be used to look at the numbers and the graphs.

Given enough input channels and access to the cables, we can monitor individual circuits going out of your distribution board. But automatically identifying and separating out individual appliances from their demand profile is a Holy Grail that, as far as I know, nobody has been able to achieve with anything better than a very moderate degree of reliability. We don’t measure in enough detail to be able to do that automatically. Your eye, and a knowledge of what you were doing and when, followed up by a bit of detective work, is likely to be just as effective if not better.

This is why I asked about what you needed now and what you thought you might need in the future. You can add an emonTx to the set-up at any time - that would give you the 2 channels in the emonPi plus 4 in each emonTx you add, but if you know exactly what you might need in total, that might not be the most economical route.

For now, given that all you want initially is the total consumption, an emonPi with 5 V d.c. power supply and emonCMS software on an SD card (all included), plus an a.c. adapter to measure the mains voltage (for best accuracy) and a current transformer to clip on the main incoming cable, is what you need. And access to your WiFi (or an Ethernet socket nearby and an Ethernet patch lead).
You’ll need two mains sockets close to your incoming supply where the emonPi will go - one for its power supply and one for the voltage monitor.
You do need access to a single-core incoming cable - probably next to your meter - on which to clip the current transformer.

My first thoughts are: First, what business equipment were you running, and can you estimate their consumption - it might not have been quite what you thought; and second, the most energy-hungry loads are usually heating. Those should show up readily in emonCMS when you’ve gathered enough data.

Hi Robert,

Very many thanks for all the info I will order what you are suggesting :+1:



I’ll highlight this as it is easily overlooked as a requirement.

Can you send a photo of your meter location and / or the Distribution unit?

If the wiring inside the distribution unit allows and you are confident in doing so, it is sometimes possible to put one of the CT Clamps round the cable for one circuit so you can monitor just that circuit.

Hi Robert,

I will have to get a twin surface mount socket installed, I will get the front off the distribution board very soon and send on the internal image, bye the way as I in Southern Ireland can the software be configured to show Euros per Kw hr?



You might find you can get to the circuit wires as the Distribution Unit is quite large. However, you do need access to the mains feed from the meter as the CT clips round that.

Do mind your fingers! Is the meter through the wall to the right of the board? I presume all the outgoing circuit wires are in that large trunking.

I’m not an emonCMS expert, it will need somebody who is to answer that.

Hi Robert,
That trunking is only for the heating timer/switch



Hi Robert,

Can you tell me what the Optical Pulse Sensor does, do I need one?



It reads the flashing light on the front of the meter if you have one. Only really needed if you can’t fit a CT. Doesn’t give instantaneous load.

It counts LED flashes from your meter. Two points: First, it’s totally accurate by definition (even though it might not be!); second, you’ll only know you’ve consumed a unit of energy after the event, when a pulse comes in. The c.t. measures power, and will give you the information at 5 second intervals (by default - it’s usually fast enough.

Your main use for the pulse counter would be to calibrate the c.t. accurately.

Note that if you have P.V, it won’t help much because it won’t count exported energy.

Ah OK were does it fit, on the meter or on the incoming cable to the distribution box?

On the front of the meter, covering the flashing LED.

Many Thanks :+1:

So you’d need to get a cable from the emonPi through to the meter - and the supplied cable has a RJ45 plug fitted and the cable is approx 1 m long.

Hi Robert
Me again! my meter is on the outside wall so at least 5 mtrs from the distribution box by the time it has gone up the wall and through the loft (bungalow) would an extension cable male/female RJ45 be suitable or would that affect the signal?