| phil-news-nospam@ipal.net 2008-02-28, 5:26 pm |
| On Thu, 28 Feb 2008 12:11:16 -0600 bud-- <remove.budnews@isp.com> wrote:
| http://www.mikeholt.com/files/PDF/L...sion_May051.pdf
| has an illustration of a surge coming in on a cable service (pdf page
| 40). The problem is the ?ground? wire from cable entry block to power
| service is too long allowing a damaging voltage between cable and power
| wires. A power service suppressor would do nothing to solve the problem.
|
| Cable, phone, ... other entry protectors need to protect to ground and
| have short ?ground? wires to the earth conductor at the power service.
| Otherwise the guide says "the only effective way of protecting the
| equipment is to use a multiport [plug-in] protector". A N-G bond in the
| power service also helps limit the voltage difference, particularly if a
| power service surge suppressor is not used.
If you do not have the proper common entrance for all services in one place,
then the effectiveness of the surge protector power strip will be reduced.
It's still better to have one than not. But it is no replacement for having
the correct entry protection, which includes cable, phone, and power coming
in at the same location and grounded together so voltage differences between
these types of wiring are eliminated (at least with respect to surges coming
in from outside on the wire).
| A guide on surges from the US-NIST cites US insurance information that
| indicates equipment most likely to be damaged by lightning is computers
| with modem connection and TV related equipment - presumably with cable
| connection. All can be damaged by voltage between signal and power wires.
The differential voltage is the most common event, so this is certainly the
issue most needed to be addressed.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2008-02-28-1545@ipal.net |
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