Are variac's used in the modern electronic's world of computer's.
Is there a need to isolate equipment and have external power suppy
regulation from ac spike's. LOOSE WIRE

 

Varics still exist and isolation is still a requirement in some applications

 

What general type of equipment.

 

see http://en.wikipedia.org/wiki/Variac for more information

 

They are used where their is a consistent drop or excess in voltage, to bring the AC voltage into spec. Sometimes power companies aren't consistent in taking care of these problems and it is easier to use something like this to take care of business.

They are also one of the original variable power supplies.

 

At a former employer, some of the assembly technicians used variacs to control the temperature range of their heavy-duty soldering irons. Not as accurate as a true thermostatically-controlled iron, but about 1/10 the cost.