AC/DC Hall effect detection circuit??

[frascati]

I would like to set up a simple experiment for a Hall effect or MR chip.

A relay energizes a 115vac light bulb whenever 5 amps of AC or DC current is flowing through a 16ga stranded copper wire. 

I cannot loop the wire.  I cannot separate the wire at either end. 

I am not a student (this is not an assignment), nor an engineer (obviously).

There are hundreds of hall effect devices out there at dozens of distributors.  There has got to be something that will simply do what I've described above. 

Any suggestions please?
Thanks so much.