You have a misunderstanding of what it means by not to put ammeters "in a parallel circuit".
What that statement means, is don't put your ammeter in parallel with ANY part of the circuit. Don't let current pass through the ammeter WITHOUT letting it also pass through some other component as well. Otherwise, you will get a significant voltage drop across the ammeter, and the ammeter will blow its fuse (if it was built with safety).
You certainly can put an ammeter in a parallel circuit, as long as some other component is in series with it. You need to interrupt the path of current flow, with your ammeter, and not bypass a component.
An ammeter can theoretically measure current in any circuit branch - it depends on what current you wish to measure.
In a parallel circuit, the current from the source is the sum of the currents in each parallel branch. So, if you wish to measure total current of the parallel circuit, apply the ammeter at the source, or, if the parallel branch loads are constant, you can measure the current of each branch, add them and the sum is total current at the source.
How do these people come to that conclusion? Ammeters do not "know" what sort of circuit they are connected to, they just measure the current flowing through them.
There is a device called a current tracer that be used to determine what branch of a parallel circuit is drawing a large current. These are very useful when you have lots of parallel branches on the power bus etc.
.http://www.arcade-museum.com/manuals-tes...
some say that ammeters are not equipped to measure current in parallel circuit, then what can i use?
