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From: kaufman@neon.Stanford.EDU (Marc T. Kaufman)
Newsgroups: comp.dcom.modems
Subject: Re: Which is better to have?
Message-ID: <1991Apr24.150807.8670@neon.Stanford.EDU>
Date: 24 Apr 91 15:08:07 GMT
References: <7244.2815110B@zswamp.uucp>
Organization: Computer Science Department, Stanford University, Ca , USA
Lines: 19

In article <7244.2815110B@zswamp.uucp> root@zswamp.uucp (Geoffrey Welsh) writes:
>In a letter to All, Jay S. Rouman (jsr@dexter.mi.org ) wrote:

- >What's considered good external protection these days?

- >Will MOV's across the line do the job?

>   There are a lot of places that'll sell you a device with one MOV accross 
>the hot and neutral lines; however, you want 120V MOVs between hot and 
>netural and between hot and ground, and a much lower (30V?) MOV between 
>neutral and ground.

Unfortunately, many line sockets are miswired, so you 30V MOV stands a good
chance of being placed across 120V.  And since 120V is "nominal" RMS, you
probably REALLY want about 200V (135 x 1.414 + safety).  And anyway, MOVs
won't do much for lightning strikes that are close -- you need spark gaps
for that.

Marc Kaufman (kaufman@Neon.stanford.edu)