My friend who operates an internet cafe has a problem; his telephone wires run parallel with the electricity wires. I told him to move it, but the current building plans don't have provisions for this (and the other plan, which is to rewire it, isn't without a big price tag too, because we'd have to pry the ceiling apart.)

As a result, this affects DSL speed. He has two DSLs installed.

Also, his dsl modem and router are close together.

I proposed to him to dig an old cpu and use it as a linux router, but this would just act as a bridge and wouldn't solve the interference by the electrical wires.

Then I thought of STP and UTPs in CAT5 cabling. The reason why STPs didn't succeed is because of the cost of shielding the wires (and the lower distance in comparison to UTPs).

But my friend has a lot of surplus aluminum foil in stock... and I was wondering... would this be a good idea? Would wrapping the telephone wires inbound and outbound with aluminum foil help in reduction of the interference?

In theory the foil might actually deflect or dissipate the interference but n the other hand it might not! As i believe it STP uses a coper shield which is earthed somewhere, i assume into the PC case or something so perhaps if the cables were wrapped in the foil and then earthed maybe by attaching a piece of wire and then attaching that to a table leg or a water pipe (i think that would be safe as the interference currents the foil would attract would be absolutely tiny) then it would be earthed and might just work. if it doesn't work then your friend might consider buying a longer telephone cable and routing it across the ceiling or floor so its a reasonable distance away from the electricity cable.

Also can i ask how he knows it is definitely the interference being the problem here? Im not doubting it as a cause as it is quite likely given the high currents etc in a power cable but he should probable try some diagnosis with moving the router or modem so that the cables are far apart and then testing the connection speed to see if there is any changes. Like i said its definitely not impossible for interference to be a problem here methinks but also other issues might be affecting it.

How far apart do the electricity line and the telephone line run? If they are about 16 inches apart (industry default is at least 18 inches apart), you need not worry about any interference.

How do you know if one DSL is slower than the other? Have you tested with download/upload speed? If so, check all wire connections between the phone jack from the DSL modem to the wall jack, all the way to the POTS or Network Interface (where the company line [telephone pole] connects to the building). In any given point, if the condition of the wire is poor try changing out the wire. A poor condition may be that the gauge of telephone line can be irregular. A gauge of 24~18 is highly recommended for all internal telephone wire system. A good UTP is 24 gauge, average is 28 gauge. Lower the gauge number thicker the diameter.

The distance (phone line used) from the wall jack to the DSL rounter should be no longer than 6 feet (DSL claims up to 12 feet is alright). And the gauge for this wire is also between 24~18 gauge. If you used regular store bought phone line extension, please replace it immediately. DSL company should have supplied you with a heavy gauge phone line extension to use with the DSL modem.

Addressing foil suggestion:
As far as I know aluminum foils contain tin as well--so they are not 100% aluminum. Although they may shield some EMF it will not be effective as having the proper clearance between the electricity line and the phone line.

Well, the reason I arrived to that conclusion is that we've optimized router, pc and client programs to use all the speed available, and yet when it comes to internet access... it still kinda falls short. Also, lately, ISP disconnections have been frequent, and we didn't used to experience that for a long time. the internet cafe operates almost 24 hours. The PCs are on Deep Freeze, so virus/worms are out of the question.

And also, I don't think cooling for the routers is a factor for speed either, but it could help, I think.



Unfortunately, they run side-by-side. I already warned him about that when the place was constructed years ago.



Uh oh. Our data rack where the router/modem is kind of exceeds that distance. As for the kind of telephone wire used, it's the 3 prong brown telephone wire. We don't have our telephone lines inside the walls, so telephone wires originate from the signal box, then the brown wire that leads to our data rack, and then the dsl splitter.

As for the interference when it comes to data signals, this applies to network cables too, right? I also found out that some of his cat5 cables run close together with electrical wires.

The reason I'm nagging him about it is because there's been competitors around, and our internet speed is a little sluggish in comparison to theirs, despite using two DSLs and utilizing around 1mbit each DSL, so that's why we've been trying to go all out sorting it out.

This post has been edited by O_H: Feb 6 2007, 04:13 PM

Are you sure that this is happening because of the electrical cables next to your network cables. As I have same thing in my home and verything is working properly actually torugh hall building cables are next to each other and we haven't noticed any actual problem.

However I would say that his problem might be in fact with server. He should use one server and connect all other computers in his cafe to the internet and then connect the server to the dsl cable or whatever he is using. I really don't see why would it be so problematic and I havent' noticed any decipation in my home network because of cables runnign close to each other.

Really reconsider that this problem is not in electrical interference. Just in organizational structure of your network.

Radio wave sielding
Using Aluminum Foil To Shield Cables?

Replying to O_H



Hi there,

It would be worth it for you to know that aluminium foil does effectively shield are.F as I have done test by wrapping a mobile phone totally in aluminium foil. The area I tested it had full signal and once wrapped in the foil the phone lost its signal completely as I could not phone it and when I removed the foil it said no network and then a couple of seconds later it got reception and had full signal again.

I am building a new house and I will be putting alifoil in the walls of the bedrooms at least, as when we sleep our bodies need the chance to repair cell damage so it should help in that regard. I'm not sure that I should ground wire the faraday shield though, it may be more effective?

Cheers, Grant



-reply by grant_nz