Power Surge & Blown Fuses

Something is better than nothing? I suppose as long as it isn't worse.

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Is it? So if I sell you a disposable plastic cup full of water for $10, its more than nothing, but is it a wise deal? Is it worth having? No, because

a) you've got way more water than that already b) it doesnt solve any problem c) its a total waste of money.

A good parallel to buying a surge absorber...

a) youve got way more surge handling capacity in both the low impedance mains and the input filters built into appliances and the other mains loads that will absorb power during a surge than any plugin junk can provide

b) these plugin units dont solve a problem because

- your appliances are already designed to handle what comes down the mains line

- the mains is orders of magnitude lower impedance than any surge absorber, rendering it of no significant effect

- appliances are already warrantied when new, covered by house contents insurance when used, and the odds of a surge absrorber saving anything is so remote that its not worth wasting 10 bucks on

c) see above.

NT

A powered off computer connected to a network of computers and to an adjacent plug-in protectors was damaged. We traced the surge path, located every damaged IC, replaced those ICs, and restored the entire network. Incoming path was on AC black (hot) wire. MOVs in the protector shunted that transient to white (neutral) and green (safety ground) wires. Surge then found a path to earth via adjacent computer motherboard, NIC, down network, into another computer, through that motherboard, out via modem, and to earth ground via phone line.

Plug-in protector, being too far from earth ground and too close to transistors, found a destructive path to earth via a powered off computer. In this case, nothing would have been better than something. Or something - the protector connected less than 10 feet to earth - would have protected those computers. Unfortunately, no earth ground meant no effective protection. Protectors without that essential connection to earth simply contributed to damage of adjacent computer and networked computer.

That is why SREs are used when signal wiring is included.

Your religious belief again. The IEEE guide clearly describes SRE plug-in surge suppressors as clamping all power and signal wires to the common ground at the SRE. The protection is primarily clamping, not earthing.

The IEEE and NIST guides clearly say that plug-in suppressors are effective. Links to sites that say plug-in suppressors are effective: 2 Your links to sites that say plug-in suppressors are not effective: still 0

bud--

Not at all. I promote accurate information. I agree with the IEEE and NIST guides which are based on research and engineering experience. They recommend several methods to protect against surges including single point grounding, service panel protectors and plug-in protectors. Various of the methods may be used individually or in combination. Plug-in suppressors may or may not be considered in a particular instance.

w_ consistently says plug-in protectors do not work, which is not in accord with the guides (or anything else I have read). He has not supported this position from any reputable source.

bud--

Your reply presents a significantly oversimplified picture, one designed to be easily swallowed by people without engineering understanding of the problem and its solution.

NT

Bud-- wrote in news:23f1f$4510039c$4213eb72$16094 @DIALUPUSA.NET:

Ummm... what's the difference between "overvoltage" and "surge"?

Time. Overvoltage could run for hours or days.

-- _____ _ _ |_ _| | | | | | | __ _ _ __ ___ | |__| | ___ _ __ ___ ___ _ __ | | / _` | '_ ` _ \ | __ |/ _ \| '_ ` _ \ / _ \ '__| _| |_ | (_| | | | | | | | | | | (_) | | | | | | __/ | |_____| \__,_|_| |_| |_| |_| |_|\___/|_| |_| |_|\___|_| __ ____ / _| | _ \ ___ | |_ | |_) | ___ _ __ __ _ / _ \| _| | _ < / _ \| '__/ _` | | (_) | | | |_) | (_) | | | (_| |_ \___/|_| |____/ \___/|_| \__, (_) __/ | |___/

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Duration.

If an appliance cant handle the conditions to which it is known it will be subjected, it is the appliance deisgn that is at fault. To claim otherwise is a bit... well,

NT

It is unlikely electronics would be designed to survive a near lightning strike, which could cause dammage by differential between power wires, power wires to signal wires or wires to ground. Specifically computers with phone connections on the motherboard are hard to protect from thousands of volts differential to ground, although that protection could be provided if the phone wires went through a device on the metal case that has the metal case ground available and more working space.

Most people, except apparently you, wouldn't expect apparatus to survive extrodinary events which it is known may happen.

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"Surge" - up to about 1/2 cycle

"Swell" - 1/2 cycle to a few seconds

"Overvoltage" - more than a few seconds

A loose neutral on a multiwire circuit or service is probably a common cause of "overvoltage". MOVs that work well on lightning events under a millisecond rapidly exceed their energy ratings on "overvoltage".

bud--

this doesnt address the point raised above at all.

Youve not followed this. Good day.

NT