Re: My PC was hit with lightning and now Microcenter is looking at it.
- From: bud-- <remove.BudNews@xxxxxxx>
- Date: Thu, 12 Jul 2007 09:22:34 -0500
w_tom wrote:
For reliable information on surges and surge protection try:
http://omegaps.com/Lightning%20Guide_FINALpublishedversion_May051.pdf
- the title is "How to protect your house and its contents from
lightning: IEEE guide for surge protection of equipment connected to
AC power and communication circuits" published by the IEEE in 2005
(the IEEE is the dominant organization of electrical and electronic
engineers in the US).
And:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the US National
Institute of Standards and Technology in 2001
The IEEE guide is aimed at those with some technical background. The
NIST guide is aimed at the unwashed masses.
For example, Leythos suggests a surge entered on a phone line?
Why? Telco earths an effective 'whole house' type protector on every
phone line - for free. How would a surge enter on phone line? First
lightning must bypass AC electric lines to get to phone line. Then it
must ignore earthing from a telco provided protector. Finally, to
damage a computer, first, it forms a conducting circuit to earth.
Incoming on telephone line, through modem, through motherboard, then
out to earth ground via table top, AC electric wire, etc. Right out
of primary school science - first a complete circuit must exist before
electricity (a surge) can flow.
According to NIST guide, US insurance information indicates equipment
most frequently damaged by lightning is
computers with a modem connection
TVs, VCRs and similar equipment (presumably with cable TV
connections).
All can be damaged by high voltages between power and signal wires.
An example of how a surge can enter on a signal wire is illustrated in the IEEE guide starting pdf page 40. A surge comes in on a CATV service. The CATV entry block is not connected with a short ground wire to the power service earthing wire at the power service. Surge current on the long ground wire creates a high voltage between power and CATV wires causing damage. The same can happen with the phone entry. Entry protection blocks should be adjacent to the power service with short interconnect wires. (If not the IEEE guide says "the only effective way of protecting the equipment is to use a multiport protector.")
An effective protector is simply a connecting device to earth
ground. It does not stop or absorb what three miles of sky could not
- as Leythos claims. An effective 'whole house' protector earths
direct strikes to computers as Ben Franklin's lightning rod earthed
direct strikes to church steeples. Computers are damaged by direct
lightning strikes. If that surge current is not earthed before
entering the building, then it will find destructive paths through
household appliances.
Whether a lightning rod or protector - it is only a connecting
device to earth ground. Protection is earth ground. No earth ground
(ie. that UPS) means no effective protection. Those who never learned
how electricity works will deny all this.
The 6 EEs that wrote the IEEE and NIST guides deny all this, as applied to plug-in suppressors. And no one says suppressors "stop" or "absorb".
w_ has a religious belief (immune from challenge) that surge protection must use earthing. Thus in his view plug-in suppressors (which are not well earthed) can not possibly work. The IEEE guide explains plug-in suppressors work by CLAMPING the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing. The guide explains earthing occurs elsewhere.
Note that all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. External connections, like phone, also need to go through the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires. These multiport suppressors are described in the IEEE guide. [Leythos was correct that the printer needed to connect to the UPS. I read his post as connecting the printer to the UPS surge protected outlet, not the UPS outlet.]
Plug-in suppressor ratings range from junk to very high. UPSs can have the same protection as plug-in suppressors, but suppression ratings are probably not as high as a good plug-in suppressor. Any suppressor in the US should be listed under UL1449.
--
bud--
.
- References:
- My PC was hit with lightning and now Microcenter is looking at it.
- From: gabe
- Re: My PC was hit with lightning and now Microcenter is looking at it.
- From: Leythos
- Re: My PC was hit with lightning and now Microcenter is looking at it.
- From: Todd H.
- Re: My PC was hit with lightning and now Microcenter is looking at it.
- From: Leythos
- Re: My PC was hit with lightning and now Microcenter is looking at it.
- From: w_tom
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