On 5/19/2016 12:19 PM, philo wrote:
On 05/19/2016 07:55 AM, wrote:
philo: "MOV"?



http://www.howtogeek.com/212375/why-...rge-protector/

Pretty much internet garbage.

For instance (contrary to the link) if a MOV with a 1000J rating is hit
with 1000 - 1J hits, the cumulative rating is far greater than 1000J.
Look up a data sheet.

And the amount of energy that can make it to a plug-in protector over a
branch circuit is surprisingly low. A surge expert at the NIST
investigated how much energy can reach the MOVs. Branch circuits were
10m and longer, and surges coming in on power wires were up to 10,000A.
The maximum energy was a surprisingly small 35 joules. In 13 of 15 cases
it was 1 joule or less. Plug-in protectors with much higher ratings are
readily available. (There are a couple reasons the energy is so low, if
anyone is interested.)

(The surge of 10,000A is, for practical purposes, the maximum surge
exposure for a house. It is the result of a 100,000A lightning strike
(only 5% are stronger) to an adjacent utility pole in typical urban
overhead distribution.)

And the IEEE surge guide (link in trader's post) describes how the
protected load can be connected to the incoming power, or connected
across the MOVs. In the latter case, if the MOVs fail the protected
equipment is disconnected. I believe protectors made now are required to
state if the protected load is not disconnected.

Some manufacturers have protected equipment warranties. They are
possible because the risk is much more limited than we expect (as
explained above).

I don't expect any of my plug-in protectors, which have good ratings, to
fail.