Question: I have read and researched online about electric monitoring systems like the kill a watt and wattspn and i have observed something in vpmmon, they do reuire intrusive devices like sockets as means of controlling (on or off the devices) and monitoring mechanism. Now is there a diffent way or idea in order to control and monitor electric appliances in a non intrusive way (without using additional sockets to be placed on each load)? I know non intrusive mechanism can do monitor stuff like what is on or off through voltage variations, but it cant control the loads like turning them on or off. Thanks

Answer: 
On/off control is, by definition, intrusive. ie  

 The act of turning something off IS intrusive.  

 The act of turning something on IS intrusive. 

BUT: 

You can measure AC current without intrusion and  

 You can measure AC voltage with very close to zero intrusion. 

While it IS possible to monitor voltage without intrusion in the strict sense  

 ie with no ohmic connection, by using eg capacitive coupling,  

 there are few circumstances where this makes practical sense.  

 Even DC voltage may be measured using electrostatic methods but this would essentially never be done in AC mains measurements.  

 Long long ago I did see and electrostatic DC meter ! Rare.

Ac current can be measured by detecting the field produced - most usually with a Hall sensor.  

 Special ICs are made for this purpose.

Clamp meters of the sort shown by Rocketmagnet in his answer are also useful. 

[Here is an AC current sensor](http://www.allegromicro.com/en/Products/Part_Numbers/0756/0756.pdf) which uses a Hall sensor.  

 The current path is built into the IC for precision but this is not essential.  

 There is no "ohmic" contact with the current path. 

![enter image description here](https://i.stack.imgur.com/zvSPA.jpg)
While it is possible to measure load current in a non-intrusive way, using a clamp ammeter like this:

![Clamp Ammeter](https://i.stack.imgur.com/py8AJ.jpg)

It is not really possible to control the current in the cable. Certainly not possible to switch appliances on and off.