Anyone have an idea of what the 'typical', domestic, peak current draw in the UK would be?
At a guess I would say 60A, as most ring main wiring is 30A and throw in another 30A for cooker and central heating wired directly in.
Average ? and not max !!!
I guess it all depends on what you mean Average !!!!
using a clap on watt meter and taking readings .
I use around 10kwh per day or 400 watts
ooops didn`t see the peak !!!
It depends 
Why do you ask?
For comparison, a typical home in the US usually has 200AMP service @110AC vs. 220AC in Europe, of course usage varies
Yes, we are resource hogs
Trying to size a current transformer so I can measure domestic electricity usage
You shouldn't need a transformer, you can use a clamp-on probe similar to this one http://cgi.ebay.com/UEI-CA40-AC-DC-CLAMP-ON-CURRENT-PROBE-1000-AMPS_W0QQitemZ400001398891QQihZ027QQcategoryZ50961QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Generic clamp-on probes can be found for about $20-$30
Or you can use an AC shunt, but an inductive probe is better overall
How much accuracy are you looking for?
It can be very dangerous to hook anything directly up to your line and in some countries it is quite illegal as well
That is over complex !!!.
Just get one of these . http://www.eco-eye.com/
Or one of these P3 Kill A Watt Electricity Load Meter and Monitor - Newegg.com
Can be found for $13 when it is on sale, sometimes even with free shipping
Sadly newegg only ships to the US, Canada and China
At a guess I would say 60A, as most ring main wiring is 30A and throw in another 30A for cooker and central heating wired directly in.
In the UK, they use 230 volt service, so I would guess it would be half what it is in North America. An oven and clothes dryer are each around 230V, 30A. A coffee-maker would be 115V, 10A. So the peak draw can vary wildly.
In North America, we do have 230V coming into the home, half on each side of a center rail. I'm not sure if Europe is similarly wired with 460V coming in or they only have 230.
Gromski for you live in the u.k ... you can get them from maplins etc.
OK, let's assume that I'm here because I actually want to put something together myself rather than just buying it off the shelf.
Whilst the clamp-on meters are fine I want to be able to graph this data over time and display it on a PC.
I may just get a cheap one from Maplin and take it apart.
@gnu_linux > the name seems to vary depending where you look. Some people call them current transformers, others split core current probes etc. I'd like accuracy to be within 10% or so.
A clamp-on probe which works by induction is the best way to do this without burning the building down
All you need to do is interface the clamp-on probe to an arduino and you can graph it on your PC all day long
Alternatively you can get a digital multimeter with an RS232 interface and plug the clamp-on probe into it and graph the data on your PC
The Mastech MAS-345 is a fairly inexpensive unit with nice features, it sells for about $40 - $50
$60 at amazon
I have seen it on ebay for about $40
I've actually been looking at split-core CTs (http://www.dentinstruments.com/CurrentTransformers.htm) and mini Rogowski coils (http://www.pemuk.com/)
For reasons that escape me the average price for a split core CT seems to be in the 100s of £ region.
You can get them for $30 on ebay + $50 for the MS-345 with RS232
$80 and you can graph your usage in real time
Total about 55GBP
Wattson (http://www.windtrap.co.uk/energy-saving-devices/electricity-monitors/wattson-sensor/) and Owl (http://www.windtrap.co.uk/energy-saving-devices/electricity-monitors/owl-sensor/) seem to be able to sell their CTs for around £9 ($13) and I can't work out how.
MAS345 $42
Clamp-on meter $15
I have seen the clamp-on probes for $30 on ebay although the high end ones sell for about $70-$140
this £29.99 meter from Maplin has a USB interface: http://www.maplin.co.uk/Module.aspx?ModuleNo=222041
@mem Interesting, thanks for the link
Please note that users are reporting driver problems with that meter for 29.99GBP
I wonder if it works on Linux, BSD and Mac...
For those that care the MAS-345 with RS232 does work on Linux, BSD and I think it works on Mac too
I wonder if it works on Linux, BSD and Mac...
Looking at the Q&A on Maplins web site it looks like it uses a Silicon Labs USB to RS232 bridge. If that is the case then there is no problem with running this off a Mac or Linux.
The maplin meter (N56FU) I linked in post #16 above does use the siLabs CP210x USB to UART bridge and drivers are available for OSX and Linux: Silicon Labs
I have both meters, the N56FU and the Mastech, I tend to use the N65FU more.
N56FU advantages:
- Measures frequency/duty cycle
- Higher precision (3/34 digits)
- More sensitive: Voltage down to 60mv, current down to 600ua
- USB connectivity to PC
Mastech advantages:
- serial protocol easier to parse if writing custom software
- rs-232 easier to interface to Arduino