Bruce L. Bergman wrote:

On Sun, 16 Oct 2005 22:28:13 -0700, "william_b_noble"
wrote:

"Ray Field" wrote in message
news:47E4f.38843$ir4.33050@edtnps90...


Are "surge protectors" any real help in protecting electronics? Some years
ago I had the details for wiring and components to make a home brew surge
protector - lost with all the other "gonna do" projects.

a proper surge protector will protect your electronics, but if you have
serious lightning, it must be a multi-stage device - you put a heavy duty
protector at the power panel, and then you can use a spark gap followed by a
small inductor and then a MOV to protect the electronics.


Lightning arrestors at the main power service and scattered through
the house will help greatly in preventing damage to your 'stuff' from
lightning strikes in the surrounding neighborhood, or that hit the
power line a fair distance away.

But if you get a direct strike on your property, or on the power
line within about a quarter mile of your house, all bets are off.

A healthy direct lightning strike right on the pole serving your house
can easily overload or outlast the shunting capacity of any arrestor.

Unless you believe in spending large coin on some serious overkill -
like the huge power utility duty arrestors and a big welded 4/0 copper
cable grounding grid running around the perimeter of your property
(the kind you'd use as a ground counterpoise on an AM Radio broadcast
transmitter tower) to dissipate the charge.

Oh, and don't forget that the lightning strike can come in on the
telephone and CATV lines, too. And can strike a broadcast antenna or
satellite dish on the roof. You have to bond and protect these other
paths, too.

Lightning isn't the only threat. I used to
loose an antenna preamplifier about twice
a year until I figured out that static buildup
was taking it out, usually after a strong
dry wind. Grounding the antenna and mast
fixed the problem.


I have the whole-house breaker-style Murray arrestor on our main
panel to deal with smaller surges, and if we ever get a really big
direct strike "Sh*t Happens". Luckily, lightning storms are a fairly
rare occurrence in Los Angeles.

-- Bruce --