Why thank you. I am overly curious by nature and have just discovered that the small current can be heard if placed against the eardrum. The red clip seems to produce a different sound to the black; the red being more noticeable and slightly louder whilst the black is somewhat understated. I have just begun my first zapper-attack...so I shall soon see if I am awarded positive results.
In regards to the copper pipe query, I purchased them from Homebase (a fairly large chain of stores in the UK), but shall be looking to find more appropriate pipes soon...presumably from a plumbing outlet. The pipes I have at the moment are about half the size I was looking for, but it was either them or nothing.