This is what I use for the monitoring. You can buy extra clamps and an optical sensor.
http://www.ebay.co.uk/bhp/current-cost-envir
Then I connect it to a Raspberry Pi for the logging.
Going to cost you about £100 to get it all sorted.

And CurrentCost went bankrupt recently and not sure if they have phoenixed or not.

It is the same as the EON one.
I use the USB cable as I can then use the default sample time of 6 seconds (ish).

I wrote my own script (actually modified others). Then installed Upstart so that it was live as soon as the RPi boots up.

#!/usr/bin/python

import serial, time, datetime

while True:

#Open the USB Serila port
cc128 = serial.Serial("/dev/ttyUSB0", 57600, timeout=6)

#Read the USB Serial port
text = cc128.readline()[:]

#Splits up the data
length = len(text)
dsb = text[32:37]
time = text[49:57]
temperature = text[70:74]
sensor = text[89:90]
sensorID = text[103:108]
ch1 = text[139:144]
ch2 = text[170:175]
ch3 = text[201:206]


#Sort out the time format
timestamp = datetime.datetime.now().strftime ('%d/%m/%Y %H:%M:%S')

#Opens and writes to the text file where the data is stored
tfile = open("/home/pi/homemonitoring/ccdata.csv", "a")
tfile.write("%s"%timestamp + ",%s"%length + ",%s"%dsb + ",%s"%time + ",%s"%temperature + ",%s"%sensor + ",%s"%sensorID + ",%s"%ch1 + ",%s"%ch2 + ",%s"%ch3 + "\n")
tfile.close()

time.sleep(6)

Shame how the forum chops whitespace off the start of lines when it's significant in Python. Perhaps you could put that on pastebin or as a github gist or something, Steamy.

A word of warning though: those CurrentCost devices vary a lot from version to version in what they output so Steamy's code might not work exactly as is for newer ones. Should be easily modifiable, though. Mine puts out XML and I did some quick and dirty code to parse that (also in Python) using the default Python DOM implementation. It relied on a one second timeout to determine when a burst of lines (which come, as Steamy says, every 6 seconds) was complete.

Thanks, the multiple channels will be very handy for what I want to do. Looks like the CurrentCost EnviR is supplied free by some electricity suppliers and new ones are finding their way directly to eBay quite cheaply. I shall try to bag one of those.

Sorry, mine's in storage about 30 km away so a bit awkward to check Hope somebody else can help.

I power the CurrentCost from the 3.3 or the 5V pin on the RPi no problem.

Ed
My initial codes was written by someone else and that hourly, morning noon and night, daily, weekly and monthly output used to cause all sorts of problems.
Why, with my very limited understanding of coding, I simply split the line up.
I have a later version that does a conditional check on the line length and only saves when the length is correct. Bu tit is messy and probably not reliable (I have one at a bakers at the moment and must go and check it.

Also worth knowing that the RPi does not have a clock, and can be flaky on its timekeeping even when connected to the internet.

BTW, has anybody found or used any one-wire current sensors?
Ive seen this:

http://www.hw-group.com/products/sensors/30A-Current-probe-1W-UNI_en.html

but haven't looked closely or investigated yet.

Posted By: djh

Posted By: SteamyTeacan be flaky on its timekeeping even when connected to the internet.

If you have a connection to the Internet your timing should be perfect. You need to set up an ntp daemon (Network Time Protocol). googling 'pi ntp' throws up lots of likely how-to hits.

Edit: PS the sheepwalk RPI3 one-wire plug-in also contains a clock.

You can also add a real time clock module for a couple of pounds from the bay. Probably easier to use NTP though.
(Mind you my OSMC seems to have REAL difficulty keeping time despite supposedly using NTP, my latest thing has been to set up a cron job to manually update the clock from NTP every 15 mins. It's a mystery!)

Is there such an animal as a multiplexor for the 1 wire sensors around for the Pi (so you can have LOADS of sensors)?

I use RTCs and ntp, it still gives me grief. Could well be something I a doing.

One point that nobody has mentioned, I think: if you have solar or other microgeneration, you really want a monitor which can sense which way the energy is flowing (into or out of the grid). This is not the case for our monitor, an oldish Current Cost, bought before we installed PV. It is now basically an expensive room thermometer.

Thanks for the recommendation. I bought an Envi R from eBay heavily subsidised by e-on.

It is a surprise to find I am consuming 500W without anything really being switched on. Half turned out to be the fridge and freezer, but of the other half there isn't much that really needs to be on. It will be a useful tool.

I think the fridge is working properly. It's one of those silly Samsung american style things which despite being A++ rated uses about 600-700kW/h per year which averages out at about 70W continuous. I measured 171W when it was running and it does switch off. The freezer is an old second hand thing running about 85W continuously. I might see if the other half really needs it now she has the silly fridge freezer.

There is still a fair drain with everything switched off. The building was commercial and I've still not removed the emergency exit lighting which must be worth 100W on it's own.

I'm not planning to log just yet - I have a monthly log of electricity and gas consumption and gas is coming down nicely. It's the steady rise in electricity consumption I want to turn the other way around and the EnviR should be helpful. I might well buy a plug in.

The electricity meter has daytime and night readings. I hadn't previously normalised the night reading with the day reading (day = night * 2.42 for a 17 hour day and 7 hour night to get them on the same scale). Looks like just about all of the electricity is used by stuff that is on all the time. That is really wasteful.

Posted By: vordI'm down from 500W to 230W continuous so far, with another 40W phantom current on a lighting circuit and upstairs sockets that can probably go once I figure out what is using it. The biggest reductions were switching the fridge to eco mode and the other half turning things off when she saw the monitor.

When you get to those sort of levels, power factor errors can loom large. The currentCost makes fixed assumptions about power factor and voltage. If all that's left running is a few switch mode PSUs the figure shown on the CC may be significantly more than reality. I spent ages trying to find out why I was seeing around 150W when I was only expecting around 80W (both figures v. approx from a dim dark corner of my memory). I only found the solution (which was that there was no extra load, just a false reading) by waiting till a quiet day with no one else around, powering the CC itself from an unplugged UPS, and turning off each of the known (& individually checked using a plug-in monitor) 24/7 loads one by one. As each device was taken out the CC reading dropped by more than each device accounted for. With all known loads off the CC reading was zero...

YMMV.