Yes, the knob and tube wiring I have seen is as you describe, with large loops of fields from small amperage. Though this method was abandoned in the 40s, there are a lot of buildings in some areas such as San Francisco which like to preserve older buildings where one finds this wiring still. It is legal to leave it or even add on to it, but not to install new.
It is interesting to consider that early house residents may have been exposed to higher EM fields even with minimum electrical usage than those in modern high-load houses which are wired according to present Code. An interesting study did show that cancer has risen following early electrification in areas previously not served. With knob and tube, the early users were getting a good dose of magnetic fields!
Karl
