This power meter do you think it'll read the consumption of power thats being used without plugging a power tool into it? I think it will because whatevers on the ringmain its plugged into will give a reading?
How can it measure something not plugged into it? That's why it has a socket, doh! It's like trying to measure a window by holding the ruler up to the door.
You need a different method to measure the current in the ring, e.g. a clamp meter, and the knowledge of how to use it.
A useful DIY adjunct to a clamp meter is a shortish plug and socket extension cord. One can then clamp between the plug and the socket (which obviously feeds the device under test) and see whether current is flowing. fr'instance switch the heaters ON and see whether the washing machine's heaters are working. It can save hours/minutes of testing. [Dribble will probably swear that real men use a hacksaw and gauge the size of the arc.] [[ Dyed-in-the-wool sparkies will insist that one takes the top off a plug and insert the leads of their trusty war-surplus AVO in series with the LIVE conductor where the fuse 'lives; if the range selectors are wrong they'll just tape down the reset button, ]]
Might be worth mentioning that ones special extension lead needs a length of outer insulation stripped from it so that you can clamp round the individual wires rather than the whole cable. (otherwise you end up measuring the sum of the current flowing in and out of the appliance (hopefully nil!)
Another handy trick is to make a small coil of say ten turns in one of the wires. Clamp round that and you will read ten times the actual load
- hence adding a decimal place of resolution to your meter.
No, the best you will get without something plugged into it, is you will be able to measure the voltage.
There is a secondary issue here as well, if the description is to be believed then this one does not seem to take account of the power factor of the connected appliance either. Hence on reactive loads (computer kit, fridges, freezers, and the posher power tools) you will get answers that are somewhat out.
Maplin do one that while not perfect is better specified: (currently on special)
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you want to measure loading on a whole circuit, or a whole house, then a true RMS clamp meter will allow you to monitor the current load.
(For a circuit measurement you can clip it round the wire leaving the MCB in the CU, and for the whole house clamp round a meter tail).
Round one side of it - so the clamp joins up through the centre. The idea being you want the current flow to pass through the clamp ten (or however many times) in the same direction. If you clamp right round the coil you are back to measuring the sum of current flow in two directions (so it would cancel out and you are back to nil again).
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