Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!genrad!panda!talcott!harvard!seismo!brl-tgr!tgr!jrv@mitre-bedford From: jrv@mitre-bedford Newsgroups: net.ham-radio Subject: MOV transient protectors Message-ID: <9024@brl-tgr.ARPA> Date: Thu, 7-Mar-85 01:26:47 EST Article-I.D.: brl-tgr.9024 Posted: Thu Mar 7 01:26:47 1985 Date-Received: Sun, 10-Mar-85 06:47:44 EST Sender: news@brl-tgr.ARPA Lines: 13 I can't see why more than one MOV would be necessary to protect the AC power (hot to neutral), because I can't see anything that would drive a transient from hot to ground or ground to neutral. Big, inductive loads switching on and off (motors, relays) create transients from hot to neutral. Any sources outside the building can only drive transients from hot to both ground and neutral, because ground and neutral are connected at the circuit breaker box. Assuming the building is wired with grounded outlets, all three wires run in parallel from the breaker box to the outlet, so even VHF radiation can't drive a big differential mode signal. The only source I could think of for a big signal from ground to something else is a lightning strike to just one wire - and I wouldn't expect any MOV to handle that! - Jim Van Zandt