Re: Lightning strike protection

On Jul 24, 10:03 am, w_tom <w_t...@xxxxxxx> wrote:
On Jul 24, 8:34 am, "cody chunn" <cchu...@xxxxxxxxxxx> wrote:

IMO: Units with isolation transformers generally do not need any added
protection. If you get a pop big enough to jump the transformer, asurge
suppressor isn't going to be much help anyway.
.
Transformers do not protect from surges that appear hot-to-neutral. A
high voltage across the the primary produces a surge on the
secondary.


The best information on surges and surge protection I have seen is in
a guide from the IEEE:
<http://www.mikeholt.com/files/PDF/
LightningGuide_FINALpublishedversion_May051.pdf>

And a less technical guide from the NIST:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf

Both cover service panel suppressors, plug-in suppressors and other
information.

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 phone/cable
wires.

If you use a plug-in suppressor 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.
.

All appliances have (and are required to have) internal protection.
.
Required by who?
.
Plug-in protectors cannot avert this type of damage.
.
Nonsense.
.
Plug-in
protectors require a 'whole house' protector.
.
Nonsense.
.
Plug-in protectors do
not protect from a type of surge that typically causes damage.
.
Nonsense.
.
Anything that a plug-in protector
claims to accomplish is performed by one 'whole house' protector.
.
I agree that service panel suppressors are a good idea.

But from the NIST guide:
"Q - Will a surge protector installed at the service entrance be
sufficient for the whole house?
A - There are two answers to than question: Yes for one-link
appliances [electronic equipment], No for two-link appliances
[equipment connected to power AND phone or cable or....]. Since most
homes today have some kind of two-link appliances, the prudent answer
to the question would be NO - but that does not mean that a surge
protector installed at the service entrance is useless."

Service panel suppressors do not prevent high voltages from developing
between power and signal wires.
.
A protector is only as effective as its earth ground.
.
As I said in a previous post w_ has a religious belief (immune from
challenge) that surge protection must directly use earthing. The IEEE
guide explains plug–in suppressors work primarily by clamping
(limiting) the voltage between wires to the ground at the suppressor.
The voltage between wires going to the protected equipment is safe for
the protected equipment.
.
When installed, a 'whole house' protector must connect
to the same earth electrode used by telephone and cable TV.
.
To prevent high voltages between power and phone/cable wires the phone/
cable entry protectors must connect with a *short* wire to the ground
at the service panel. An example of a cable entry ground wire that is
too long is in the IEEE guide starting pdf page 40.

If you have short entry ground wires and a service panel suppressor
you are relatively safe.

If plug-in suppressors are used it is typically for high value
sensitive electronics connected to both power and phone/cable.

--
bud--
.

Relevant Pages

  • Re: what is the differences between whole house surge protectors?
    ... secondary surge arrestor and one is a transient voltage surge suppressor. ... "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. ... Unfortunately for w the IEEE guide explains plug-in suppressors work by clamping the voltage on all wires to the common ground at the suppressor. ...
    (alt.home.repair)
  • Re: are surge protectors rated in Joules or Amps?
    ... "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 guide cautions against comparing Joule ratings because there is no standard for measurement. ... It is too bad, because Joule rating, like w_ says, is an indicator of suppressor life. ...
    (microsoft.public.windowsxp.hardware)
  • Re: After Lightening Storm - Computer Will Not Turn on
    ... And this explains why the surge worked. ... Excellent information on surges and surge protection is in a guide from ... All can be damaged by high voltages between power and signal wires. ... suppressor, or interconnecting wires need to go through the suppressor. ...
    (alt.sys.pc-clone.dell)
  • Re: Surge Protector
    ... Surge energy rating 540 Joules ... Any surge suppressor sold in the US should be *listed* under UL1449. ... The best information on surges and surge protection I have seen is at: ... "How to protect your house and its contents from lightning: IEEE ...
    (rec.sport.football.college)
  • Re: Surge protectors to use with home electronics when grounding is not available?
    ... Most commonly damaged equipment has connections to both power and signal wires. ... A lot of surge protection is keeping the power/phone/cable wires at about the same voltage. ... Plug-in suppressors can provide protection but can shift the ground potential at the suppressor. ...
    (sci.electronics.basics)
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