I don't know why, but I do know it hasn't always been this way. Years ago the standard voltage was 110V, then for some reason it was upped to 112V, then 115V, then 117V, and now 120V. As for the frequency, many such decisions were completely arbitrary in the early days of electricity. I do know it is easier to filter than the 50Hz used in Europe and elsewhere, and allows slightly smaller power transformers. My guess it relates more to available technology at the time than through a conscious decision. The choice of a power line frequency has affected the development of TV in the respective countries as well, since the vertical refresh rate was chosen to match the power line frequency to minimize interference. CIAO - Martin. On Wed, 28 Jan 1998 07:07:36 -0800, richard dellacona wrote: >hello out there does any one out there know why 60 cps and 120 vac >is used in usa for line voltage no one seems to know or have a good >answer for this question Martin R. Green elimar@NOSPAMbigfoot.com To reply, remove the NOSPAM from the return address. Stamp out SPAM everywhere!!!