Devices to connect to a surge protector

[Marosp]

I understand some of the arguments for using a surge protector with sensitive electronic equipment. However, I'm wondering whether there is any potential benefit from connecting devices with batteries (such as a laptop, iPad or iPod) or whether the battery would absorb relatively minor fluctuations offering protection in these circumstances.

I realise a significant enough surge (e.g. caused by lightning) could damage/finish off devices but these surges occur very rarely where I live.

Also, I've read that a surge protector should never be used with a step-down transformer. Would there be similar dangers connecting a digital controller for a kids train set to a surge protector?

[allikat]

The answer is: Everything, or nothing.
If you have your machine plugged into a protector, and any other device on the same wired network isn't, then that's a route into your machine.

Why should a step-down transformer not be used with a protector? I don't understand that. Since every PSU in any computer does exactly that.

And whether a device has a battery or not, does not affect how capable it is of getting damaged by a power surge. Only devices with an MOV (Metal Oxide Varistor) have a way of protecting themselves against AC spikes etc, and that includes surge protectors and many good computer PSUs. Even then, a sufficiently powerful surge may kill the MOV.

[IPexpress]

One problem with surge protectors is that when the MOV has expended its life, quite often there is no visual indication on my surge protectors, particularly the cheaper ones, so difficult to know when to replace one. Mind you, it would probably put the cost up significantly on the cheaper surge protection devices if an LED or some indicator was used to indicate it was time to replace.

[westom]

Originally Posted by Marosp

I understand some of the arguments for using a surge protector with sensitive electronic equipment. However, I'm wondering whether there is any potential benefit from connecting devices with batteries (such as a laptop, iPad or iPod) or whether the battery would absorb relatively minor fluctuations offering protection in these circumstances.

You have assumed a protector does things it does not do. Does things only claimed by hearsay.

First batteries do not absorb such fluctuations. From basic circuit theory, the battery is essentially a conductor (a wire) to such fluctuations. Any current variation on one side of a battery also appear simultaneously on the other side.

A protector is only for surges that are typically destructive. Lightning is the classic example. But others also exist. For example a stray car that hits a telephone pole. Protectors that make such transients irrelevant do not actually do any protection. Understand why advertising and hearsay does not mention this. Such transients are connected low impedance to earth. Or no protection exists. A protector either connects destructive transients low impedance (i.e. 'less than 10 feet') to earth. Or the protector is doing nothing useful.

Do not spend $hundreds or $thousands for adjacent protectors. Earth one 'whole house' protector to make typically destructive and other transients irrelevant. This is how it was done even 100 years ago.

Best protection means increased separation from appliances. And an 'as short as possible' connection to single point earth ground. Because that earthing (not a protector) does the protection. And because separation also increases protection. Then a protector is doing best protection for every type of appliance.

Appreciate what a protector does. For 120 volt appliances, it does nothing until some rare transient exceed 330 volts. That number is even on a protector’s box. How often are you suffering transients exceeding 330 volts? Maybe once every seven years. Meanwhile, transients that high are made irrelevant by protection already inside all appliances. Again, your concern is the rare transient that can overwhelm superior protection inside all appliances. Therefore one earthed 'whole house' protector is essential to protect everything. Only the ‘whole house’ protector claims to protect from that unique and destructive transient.

Unfortunately, many are educated by advertising and the resulting hearsay. Then will buy grossly undersized protectors with MOVs that fail prematurely - often on the first surge. It does not even claim to protect from the other typically destructive surge.
And is then so grossly undersized as to fail on the first surge? What kind of protector is that? Profitable.

Properly sized 'whole house' protectors earth even direct lightning strikes. And remain functional. Again numbers. A direct lightning strike may be 20,000 amps. So a minimally sized 'whole house' protector is 50,000 amps. So that MOVs do not fail. One 'whole house' protector also costs about same as that expensive and undersized power strip. Yes, many power strips are only profit centers. Selling a $4 power strip with ten cent protector parts even for $40 or $85. A profit center; not effective protection.

Informed homeowner earths one 'whole house' protector from more responsible companies including Square D, General Electric, ABB, Siemens, Intermatic, Polyphaser, Ditek, or Leviton. A Cutler-Hammer solution sells in Lowes or Home Depot for less than $50. To actually protect from typically destructive transients - including lightning. And remain functional.

Anything that might protect, adjacent to an appliance, is already inside that appliance. Your concern is the rare transient that can overwhelm existing protection. Everywhere that damage cannot happen, the 'whole house' protector is always earthed. Why? Because a protector is only as effective as its earth ground. That well proven solution also costs tens of times less money. Becuase protectors that actually do protection also do not have failing MOVs.

Your telco disconnects all phone service all over town with each approaching thunderstorm? Of course not. So your town is without phone service for four days after many thunderstorms? Of course not. Their switching computer is threatened by about 100 surges with each storm. And no damage. Because telcos earth 'whole house' type protectors. Use the only solution well proven by over 100 years of experience and science.

You have the same options. Either listen to myths and hearsay that promote high profit power strips. Or earth (a very important verb) one 'whole house' protector to protect everything. A protector is only as effective as its earth ground. A superior solution that also costs many times less money.

[bud--]

Transformers should not be a problem.

I wouldn't bet on a laptop battery protecting - depends on how it and the charging circuit are connected.
UPSs that charge the battery and at the same time power the load from the battery give significant surge protection.


Excellent information on surges and surge protection is at:
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf
- "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 a major organization of electrical and electronic engineers).
And also:
http://www.eeel.nist.gov/817/pubs/sp...%20happen!.pdf
- "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 surge guide is more technical.

Originally Posted by westom

A protector is only for surges that are typically destructive. Lightning is the classic example. But others also exist. For example a stray car that hits a telephone pole.

Car hits utility pole and high voltage distribution wire drops on wires that go to a house. The MOVs (voltage limiting elements) in protectors that can conduct thousands of surge amps for the very short duration of lightning will be rapidly burned out by much longer "temporary overvoltage". The author of the NIST surge guide has written "in fact, the major cause of [surge suppressor] failures is a temporary overvoltage, rather than an unusually large surge."

Originally Posted by westom

A protector either connects destructive transients low impedance (i.e. 'less than 10 feet') to earth. Or the protector is doing nothing useful.

Nonsense.

The IEEE surge guide explains (starting page 30) plug-in protectors do not work primarily by earthing a surge. They work by limiting the voltage on all wires (power and signal) to the ground at the protector. The voltage between wires to the protected equipment is safe for the protected equipment.

When using a plug-in protector all interconnected equipment needs to be connected to the same protector. External connections, like coax also must go through the protector.

Originally Posted by westom

Earth one 'whole house' protector to make typically destructive and other transients irrelevant.

Service panel protectors are a real 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 by themselves prevent high voltages from developing between power and phone/cable wires. The NIST surge guide suggests most equipment damage is from high voltage between power and signal wires.

A service panel protector is very likely to protect anything that is connected only to power wires. It may or may not protect equipment that also has signal wires connected.

Originally Posted by westom

Then will buy grossly undersized protectors with MOVs that fail prematurely - often on the first surge.

To pass UL1449 a protector must survive a series of surges and remain fully functional. That provides a floor of protection. (In the US you should only buy surge protectors that are listed under UL1449.)

The author of the NIST surge guide looked at energy that might be absorbed by a MOV in a plug-in protector for what is, for practical purposes, a worst case power line surge. 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.

Originally Posted by westom

It does not even claim to protect from the other typically destructive surge.

Nonsense.

Some even have protected equipment warranties.

Originally Posted by westom

Properly sized 'whole house' protectors earth even direct lightning strikes. And remain functional. Again numbers. A direct lightning strike may be 20,000 amps. So a minimally sized 'whole house' protector is 50,000 amps.

The author of the NIST surge guide looked at the surge current that could come in on residential power wires. The maximum with any reasonable probability of occurring was 10,000A per wire. That is based on a 100,000A lighting strike to a utility pole adjacent to the house in typical urban overhead distribution.

Recommended ratings for service panel protectors are in the IEEE surge guide on page 18. Ratings far higher than 10,000A per wire mean the protector will have a long life.

Originally Posted by westom

Selling a $4 power strip with ten cent protector parts even for $40 or $85.

One of the MOVs in a plug-in protector I am using has a rating of 75,000A and 1475Joules. Provide a source for that MOV for ten cents. The other 2 MOVs are rated 590J 30,000A. The protector cost under $30 and has a protected equipment warranty. (The surge current, even at the service, can be nowhere near the MOV current spec rating. The high current spec just goes along with the high joule ratings.)

Originally Posted by westom

Informed homeowner earths one 'whole house' protector from more responsible companies including Square D, General Electric, ABB, Siemens, Intermatic, Polyphaser, Ditek, or Leviton.

All these "responsible companies" except SquareD and Polyphaser make plug-in protectors and say they are effective. Westom says plug-in protectors don't work.

SquareD says for their "best" service panel suppressor "electronic equipment may need additional protection by installing plug-in [protectors] at the point of use."

Originally Posted by westom

A Cutler-Hammer solution sells in Lowes or Home Depot for less than $50.

Provide a link to a Lowes or Home Depot protector for less than $50 that has a "minimal size" of 50,00 amps.

Originally Posted by westom

A protector is only as effective as its earth ground.

Airplanes regularly get hit by lightning.
Are they crashing?
Do they drag an earthing chain?
Is it only 10 ft long?

[cypherpunks]

Originally Posted by bud--

Provide a link to a Lowes or Home Depot protector for less than $50 that has a "minimal size" of 50,00 amps.

I'm guessing he was thinking of this (doscontinued) unit.

Whis is rated 120 kA(!) at Home Depot, but I think that's a typo; the manufacturer's own documentation claims 20 kA per phase, 37.5 kA total.

This 36 kA unit is $30.

Airplanes regularly get hit by lightning.
Are they crashing?
Do they drag an earthing chain?
Is it only 10 ft long?

Indeed. The only reason for connecting to ground is to prevent an arc from leaving from less robust part of the equipment. The current will get to ground eventually; the only question is how much damage it will do on its way there. ("Ground" means "where the raindrops are falling", because they're what carry the charge from clouds to ground.)

But what's actually important is to connect all wires leading to the equipment together. One stray wire you didn't count, and you've blown it.