This is no ordinary set of pipes. There are no neutrals.
Nor are the inner pipes wired in simple parallel.
Many HHO inventors, threorists and designers alike have submitted ideas that put pipe pairs together in various shapes. Of the dozens I've seen, all use a simple parallel method of delivering charge to the inner pipes. I have found, in testing, that simple parallel distribution serves to narrow the acceptable range of electrolyte ratio to water (assuming you're using electrolyte, as most do in order to run more amps through less plate mass).
The pipe pairs are also typically the same length. This causes a 'halo' effect where charge leaks from one plate set to another, reducing the total capacitance of the electrode. The Stone-7 has a set of inner pipes that are recessed 1/4" on each end, to virtually eliminate halo effect losses.
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