Surge protection

Can someone please explain how I use surge protection. I have a Linkseys router on a BT line and lose my connection and settings every time we have a powercut/surge, etc. I have looked at a Belkin 4 way strip which says protects phone/fax/modem/DSL. At one end it has 2 small sockets which look like I should be plugging in telephone cables? So how do I set this up ? I am sorry if I sound a bit thick but I am an OAP and not at all technically minded. Hope someone can explain in laymans terms what I have to do.

There are two wires that a surge can come down - the phone wire, and the electric power wire. Both can disrupt communications.

The Belkin power strip will stop small power "spikes" coming down the power wire, but it will not protect you from power cuts, no matter how brief they are. The small sockets on the power strip are for connecting your phone line through - there should be at least one connecting cable supplied with it to enable you to connect your ADSL modem to the BT wall outlet, passing through the power strip.

Now the next bit is very important - make sure that any surge arrestor you buy which connects to the phone line is suitable for use with ADSL. Many are not, and they may actually stop the ADSL signal getting through.

If you want to be secure against brief power cuts, then you will need a power strip with built-in battery backup, like the one below, but it will cost rather more.....

http://catalog.belkin.com/IWCatProductPage.process?Product_Id=201041

You can connect your PC to this too, and it will protect your PC from short power cuts.

Edited by deleted (Wed 24-Jan-07 10:58:25)

a surge protector will not stop powercuts (or as in my case the little spikes which stop power for about a second)
If you want to keep the router running for a short time (depends on size of unit) then ideally you need a ups

I have a belkin ups which supports telephone but it doesnt have a socket for the adsl line.

The Belkin UPS I linked to is compatible with ADSL, and has phone line protection. It is also available in 3 different sizes, the bigger ones giving power backup for longer periods.

Thanks for that, I will do a bit more research

This is what I was looking at - would I be wasting my money ? I know it won't stop power cuts even if for only one second but as long as it means everything will come on back to normal instead of losing my settings on my Linksey I will be happy. It is very cheap but has good reviews.

Belkin F9H410UK2M-DB

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This is what I was looking at - would I be wasting my money ? I know it won't stop power cuts even if for only one second but as long as it means everything will come on back to normal instead of losing my settings on my Linksey I will be happy.`

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A very personal view here, that power protection products are sold on the back of FUD [Fear, Uncertainty, Doubt]. If you are losing settings on your kit, then I think that the kit is broken. I reckon that spikes and surges either do nothing or burn kit out so that it doesn't work at all.

Not 100% sure on that, it definately doesnt work with my filtered faceplate (I have the 500W version of that) but it may work with the plug in filters but as I havent used them for nearly a year I can't check.

the one second drops are what I bought mine for - they are fine for a couple of seconds.

Power went off last week for split second but it was enough to upset internet connection. My Linksey still worked but couldn't find my network so my son came round and put in all my settings again. This has happened before when power goes off suddenly while I am using internet but once re-set it is fine. Could this be due to something other than power cuts ?

possibly, my router doesnt like the spikes either, but mine just doesnt connect up to my internal network and requires turning off and then on again.

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I have a belkin ups which supports telephone but it doesnt have a socket for the adsl line.

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I am glad to hear it. Anyone who gives advice on cabling mains and data is adamant that they should be kept apart, where they must come close, they should cross at right angles, and never run parallel. Yet here we have a box with telephone, network and mains all together. Unless the screening inside that box is amazingly good I can see it causing the same sort of problems as you might get from the power spikes and drops it is supposed to correct. I haven't thought of Belkin as outstandingly good at screening components inside their boxes.

A surge protector can only be expected to do anything about surges. Short drops of power are outside its scope. Howver, they should normally come within the scope of a good PC Power supply. Such a PSU should also cope with the majority of longer term voltage increases or decreases you are likely to experience.

The question I have is the extent to which any power strip claiming surge protection is going to provide any protection that the PC PSU doesn't already give. I agree that this is a risk that should be considered. What is the probability that my system will be struck by a surge which damages it? What is the extent of the damage and the cost of recovering from it? Is there any risk of collateral damage, e.g. the house burning down because the computer blew up?

What is the most vulnerable part of your system? I would suggest the data. All the hardware can be replaced, possibly within hours. I have never had data damaged by a surge, but I have had it for other reasons, most noticeably a hard disk failure. The answer to that is not to prevent the cause of the damage, you can't tell what that might be, so make sure you can replace the data. Here we make a daily backup to tape so we can restore any file from up to three months ago (that is to repair damage from quite a lot of error conditions, many of them human). In addition, all data written to disk is also written to a disk in another machine.

That was all rather expensive and it doesn't prevent surges or power loss. However, I have a feeling that it didn't cost that much more than a surge protection system which might prevent some of the damage that the backup allows us to recover from.

If a machine fails, once the hardware is repaired or replaced, I can reinstall the original to the same state it was in moments before the failure and do so within two or three hours, depending on how much data and applications it held.

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Could this be due to something other than power cuts ?

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It may be caused by the power cut, but it shouldn't have that result. What happens when you turn it off? What happens if you turn it off at the wall socket? The configuration settings should be stored in the router in a non-volatile way. If they aren't, you would have to reset every time it was turned off. That non-volatile memory should be independent of power, even if the device is switched off when if full flow.

Do you really think that telephone cables don't run parallel to power cables in the street ?

But they are far enough apart to minimise cross talk - he is referring to them in close proximity

Have you saved your configuration in the router?

You shouldnt have to re-enter anything after a powercut, or if you switch unit on/off.

Close proximity for a few inches won't make any difference at all.

What picks up more noise ?

1. A power cable running one foot away from a phone line two miles long,
or
2. A power cable being two inches away from a phone line over a distance of two inches.

Option 1.

You will not get power and phones running a foot aprt over 2 miles. If you do, then the installation is incorrect and does not meet the required safety criteria.

And if it did happen it is most likely that the level of interference on the cables 2 inches apart will be higher.

The point I was making was that there are two ways that noise can travel between two cables

1. Capacitive pickup 2. Inductive pickup

When two cables are in close proximity you can get capacitive pickup, but to get capacitve pickup over a short distance requires the cables to be in very close proximity

Capacitance C = e0 (A / l) where A is the area of the capacitor plates, and l is the distance between them.

e0 is the permittivity of free space (8.85X10-12)

so, the greater distance between the wires, the lower the capacitance, but longer wires increase the capacitance because the area A increases.

Similarly, inductance increases with wire length, so the inductance of a wire two miles long is going to be much higher than one two inches long.

Edited by deleted (Thu 25-Jan-07 10:10:54)