Will I be able to use this Electric Imp set up to measure temperature & current and report it via wifi?
It looks like if I got the impExplorer kit that should cover the temperature sensing, ...

That should be fine.
... and then I was thinking of the SCT-013-020 ([more info] to measure power usage.

Be aware that as it is a current transformer with a built-in shunt resistor to convert the current to a voltage. Its output will be AC so some conditioning circuitry will be required to read it on your Imp.
You also need to be aware that on AC systems that current and voltage can be out of phase and this will give a power calculation error if you assume they are in-phase. You may need to study power factor to appreciate this.
To measure power you need to monitor the AC voltage as well. Be careful!
A better way to do this might be to monitor your incoming electricity meter by counting revolutions of the disc or pulses of the LED - depending on age of the meter. This avoids any messing with mains and will be very accurate.

It looks like the cable on that goes to a 3.5mm connector - what would I need to connect that to my impExplorer?

A 3.5 mm headphone jack socket or a wire snips to cut it off!

Also, do I need to get anything else to achieve my aims?

Study, study, study. Have a look at OpenEnergyMonitor.org where you might find some interesting information on open-source software and hardware. They will have addressed many of the issues you are going to face.


Does it look like I'd need any additional components or resistors, or should the impExplorer &amp; CT be sufficient?




simulate this circuit &ndash; Schematic created using CircuitLab
Figure 1. CT bias voltage configuration.

Since the CT gives out AC and can go positive and negative but the Imp can only handle positive voltages on its ADC input you need to bias the CT &quot;common&quot; terminal to half of the Imp supply voltage. R2 and 3 do this and C1 keeps that point stable.
If you have a second analog input available you can monitor the common voltage too. Now an instantaneous current reading can be obtained by calculatiing AIN1 - AIN2. This result will alternate positive and negative on alternating half cycles.
You will want to calculate the RMS - root mean square - value of the current. That means for each half-cycle you will square all the instantaneous readings, get the mean or average and then get the square root of the mean to calculate the RMS current value. You might want to study this elsewhere to understand why.  - At this point you still have only measured the current. You have additional work to do before you have a value for power. You should now be understanding why I recommend tapping off your existing energy meter.