Go to an old telephone store and buy any number of "C-4" ringers. Them is the brass ones that used to sit in black telephones. REN stands for "Ringer Equivalence Number" and 1 REN is the equivalent of 1 C-4 ringer. (There was a Canadian proposal to change this to "Load Number" but the US rejected it for old-times sake. Nobody is worried about how many C-4 ringers are out there, what people want to know is what the maximum load can be. However, as long as you insist on measuring things in the US, based on the size of some extremities of a long dead British king, you might as well go on with RENs.
Ciao, Vic
