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sxpsxpsxp 01-14-2008 09:25 AM

Please Help - Weird electrical issue affecting home network
I've got a bizzare situation going on at home and I'm at a loss as to what to do next. I'm an IT professional, and I am fairly certain the issue is not on the computer side of things. That said, here's what is going on:

I moved in to a new house about a year ago. I have a mini home network, so let's say I have a router and computer A in one room, and computer B in the other room. I dropped some CAT5 wire between the two rooms on opposite sides of the house, through the attic and down through the wall. At first I couldn't get computer B to talk to the router at all. It took me forever to figure out what the heck was going on, until finally I figured out that if computer B was plugged into an electrical outlet on the same side of the house as computer A, everything worked.

I went to Staples and bought two power strips that claimed to do RFI/EMI filtering. I plugged computer B into the power strip and suddenly all was good. Then about a few months ago, I started having issues again. Not only is computer B dropping a good 25-30% of network packets talking to my router, but computer A is dropping packets as well, but only if computer B is plugged into the network.

Now, computer B also has a cheapo APC UPS. The moment I unplug the UPS from the wall electrical outlet and have it run on battery, computer B is able to talk to the router on the network with 100% clarity. As soon as I plug the UPS back into the wall (into the filtering power strip, actually), it starts dropping packets again. If I plug the computer directly into the wall, it's even worse, with 90% packet loss.

I've tried a few different power strips with different EMI/RFI filtering ratings, and I tried a Monster "clean power" home theater strip, with no effect. I'm at a loss as to what to do! I had an electrical come check out the house, and the only thing he found is that one of the phases has voltage about 2 volts lower than the other, but he says this is considered normal.

Additional weird things going on at home: I can't use X10 devices. They just don't work most of the time. A SmartHome X10 wall switch with a LED which indicates receiving signals had the LED flashing totally randomly and just wouldn't accept signals most of the time. I sometimes get what sounds like an AM radio station coming through the phone. My newly installed kitchen AM/FM/TV is picking up the same thing over the radio, but only when the TV cable is plugged in. If I unplug the TV cable, the FM radio works just fine.

Please help!!!!

J. V. 01-14-2008 10:17 AM

Very unusual circumstance. The computer does not care what receptacle it is plugged into, and is physically seperated from the network cabling. This is not a wireless network right? You said a new house? New in age or new to you? My knee jerk reaction is RF interferance. It is possible that one or more of the recept's or fixtures are not connected securly (loose) resulting in a high resistance connection at one or more of the house wiring connection points. I would open all the receptacles/fixtures and check for good solid connections. If the wires are stabbed in the back of recept's use the screws instead. It does not have to be the ones you are using, it could be in another room. Do you have flourescent lighting? These type of fixtures are notorious for noise. I have a basement full of flourescents. When they are on my radio picks up the noise. This is another thing to address. From an electrical standpoint all I can do is encourage you to start opening all recept's, overhead fixtures and continued trial and error experiments until you locate the source of this interferance. Pay careful attention to the neutrals and grounds. Whites and bares. Try turning off parts of the house at the breaker box. See if you can isolate it to one or more circuits. Then you can check them out first. The electrician is correct about the voltage. did leave some distance between the electrical wiring and the CAT5 cable? If not get it seperated. This could be why it does not do it on all the recepts.....Check this first.

Piedmont 01-14-2008 12:12 PM

I also think it has to do with electric interference. Your cat5 is likely running with electrical wires somewhere and picking up their interference. I have cat5 cable connecting my wireless bridge (which is outside on my TV antenna mast) to my repeater in the basement. The easiest way was to have the cat5 go down next to my plumbing vent which already has several electrical wires (I'm not the only one who knows that's an easy route :). It's unlikely it would work well using regular cat5 cable it would've been getting lots of interference from those electrical wires. I had to use "shielded" cat5, which has aluminum foil underneath the jacket which prevents the interference from my other electrical wires so I can run them together.

If I had to guess, your computer B's cat5 is the one likely running next to electrical wires. It sounds like, when you plug in Computer B and turn it on the wire/network card is getting electromagnetic interference and thinking it's traffic. Since it doesn't understand it, it's asking your router or computer A to resend as it didn't understand the packet and they do and find out it wasn't intended for itself so drops it. Your computer B is also likely interpretting the interference as needing to repeat requests and repeating packets your Router or Computer A didn't ask for flooding the network with dropped packets and such. Interference does strange things like that. This interference may cause the computers to lose synchronization, or cause your computers to think they're both supposed to resend their packet and they collide. That would be my guess, your computer B's cat5 runs next to electrical wires and getting interference. Swap computer A and Computer B, see if the same thing happens but when you turn on Computer A. That will at least point to the location, and likely interference at Computer B's default location. If you know the cat5 for Computer B in the attic runs next to electrical wires but doesn't in the wall, try wrapping the line in aluminum foil which will reduce interference, if it runs next to electrical wires you'll probably have to swap it out with shielded cat5. Why this only works when plugged into the same side of the house as Computer A, I don't know.

AllanJ 01-14-2008 12:37 PM

Is everything truly grounded? It may help to take a bare wire, 14 gauge should be sufficient, and daisy chain it from one piece of equipment to another, attached perhaps with one of the cabinet mounting screws that goes through to the chassis. The last free end of the wire is grounded to the electrical system.

The equipment in the second room doe snot have to be on the same bare wire as the equipment in the first room.

This method has been done quite often even years ago with stereo equipment to reduce hum.

Connecting a capacitor between hot and ground will filter away considerable interference that travels via power lines. Some surge protectors have them. You would need electrical engineering background to figure out the size of a capacitor to install do-it-yourself, and the capacitor if left connected will consume kilowatt hours very gradually but 24/7.

sxpsxpsxp 01-14-2008 12:55 PM

A portion of the CAT5 run is near the electrical cable (i.e. freely hanging between the same two studs in the wall). Why would running the computer off battery instead of wall power make a difference if the issue was that the cable itself is picking up interference from the air, or from being next to an electrical cable?

I have considered shielded cable as a solution. It's not terribly expensive, but is pricey enough and entails enough work that I want to explore other options, if any, first.

I should note that the power strip I'm using, which is supposed to filter EMI/RFI (and looks like it does, to a degree), is supposed to alert me with a light if things aren't grounded. It's not indicating any grounding problems.

Piedmont 01-14-2008 01:06 PM

The only time electrical interference would likely happen is when you plug something into Computer B's receptacle and turn it on. When Computer B is plugged into the other side of the house or on a battery, there is NO electricity flowing through the problem outlet and hence you won't get interference (or likely less interference if there's a small load). However, plug it into that outlet and turn on computer B now causes electrons to flow down through the wall and I believe is causing interference with your cat5. That would explain why plugging it into other circuits of your house, or battery seems to solve the problem, as long as that outlet isn't used there's no electricity flowing through it so it can't create interference (well, it can but I'll explain later).

A simple test, put the computer on a battery and use the Cat5 cable near Computer B's outlet and see if you get interference. If things are good, plug a decent load into that outlet and turn it on. That should cause electricity to flow through it and my theory is you'll get interference and collisions. Unplug the load and see if things return to normal. If that is the case, it's interference and in particular caused when something uses electricity that's plugged into that outlet. Shielded cat5 should solve it, but I'd first elminate you have a bad receptacle or wiring by shutting the breaker off, removing the outlet, redo the wiring in that junction and replace the outlet. If that doesn't solve it try the shielded cat5 route.

*Edit* Also note that outlets are often chained together, so turning on loads in other receptacles of that circuit may or may not also cause the interference so may not be restricted to just the one receptacle Computer B plugs into, and if that the case shielded Cat5 should stop the interference from reaching the twisted pairs. With shielded cat5 the weakness then becomes the RJ45 connectors & the back of the face plate connection. They aren't protected by aluminum foil and open to interference. They make shielded ones but they're only shielded on the sides I believe. It wouldn't be a bad idea to wrap the back of the face plates connections with electrical tape (to prevent a short) then aluminum foil (to block interference).

goose134 01-14-2008 09:47 PM

Another thing to check for when you are opening outlets is that the polarity is correct. Whites on silver screw and black on brass colored screw. Computers, like many electronic gizmos are polarity sensitive. If you have a 'noisy' (electrically speaking) load on the circuit, it will transmit through the neutral and probably be exacerbated. Fluorescenents are notorious for this, as are battery chargers.

Spike99 01-14-2008 10:09 PM

When I read the original post, it reminded me of my home computer system (and its cluster of electronics). Blown mother boards, blown Power Supplies, random "system locking" and the odd blue screen. A few years back, I installed a deciated 15A circuit (on 14/2 wiring) to my computer cluster area. Since all power consumption was under 10A, I used a 15A circuit. Some might use a 20A on 12/2 wiring using 2 x Power bars into each outlet - if more then 10A consumption. Since installing the 15A "dedicated" circuit, my system has been solid as a rock.

If you can, install a new deciated electrical circuit to the computer thatis the most power hungary. It might work for your systems as well....


borninpa 01-15-2008 12:27 PM

This is interesting one. As a network engineer I am always worried about these sorts of problems but have rarely seen them. It does not appear that the interference is occurring via your cat5 cable from crosstalk. Have you tried connecting your computer B to a long extension cord and connecting to a different outlet that you are sure is on another circuit. This might confirm that the problem is on the outlet or circuit you are currently using. Refrigerators and the like are often the culprits for line noise.

Andy in ATL 01-15-2008 04:40 PM


Originally Posted by Spike99 (Post 88605)

If you can, install a new deciated electrical circuit to the computer thatis the most power hungary. It might work for your systems as well....


I think all the replies to this thread have been spot on. Spike wins the prize, though.:) I'm hooked up to a new cornputer in a new place. Computer dropping a little and acting weird...I wondered WTF? Arcing breaker in my crappy 100A panel. It is a 10 space 20 circuit GE panel with all tandems.

Imagine my surprise. I "Andy engineered" it to a circuit going to the attic and running a keyless. I never even consider if the keyless is on or not. Shouldn't really matter to the 'puter should it? Excellent bonding and non-flourescent loads are key. A clean simple circuit back to your eq. is perfect. Can you run it? Bet I could.:laughing:

Hey, Goose. Now I want to wire a recp backwards and plug an old charger into it. I always thought most electronics (and every incandescent bulb) can run reversed.

goose134 01-15-2008 08:17 PM

Negative. You will notice on the cord connected appliances in your home that one blade is wider than the other. This is to ensure that proper polarity is maintained. Any device will still 'work' but may generate noise, or slowly degrade the appliance in question. Some devices are more polarity sensitive than others, but I'm sure someone else could tell us more about this.
I was going to suggest a dedicated circuit, but I was hoping it was a simpler problem. Always start easy, then work yourself from there. I'm glad the problem was solved.

On another note, I had a similar problem at a friends house. She had 'monitor shake' (image would just vibrate wildly) and I ran a dedicated line to the printer (it was a giant commercial thing) and the shake disappeared.

mm60515 01-19-2008 10:39 PM

Whole house electric affected
I have a similar problem and am looking for a solution. I know that my whole house elcetric is being interfered/overpowered by the nearby (less than 1/4 mile away) radio transmitter of AM 1000. It's a 50,000 watt station. Almost any radio, tv or telephone plugged into the electrical outlet will gpick up this station. One tv would even "play the station" when it was turned off as long as it was plugged in to the outlet. My copper drain/waste/vent pipes even picked up the station. It freaked me out when I first moved into the house. I started buying more expensive electronic equipment and that helped. Cheaper clock radios in my 2nd floor bedrooms only play AM 1000 even when on the FM band. Battery radios do not have this problem, only the corded ones.:(
Anyway, I don't know how to fix it, I just experiment with buying better equipment. I'd appreciate any help.

goose134 01-19-2008 10:53 PM

:eek: Wow, this sounds like a major noise problem. This was actually why the wattage of stations was limited. Back in the day, there were problems with stations that were generating 500,000 watts and people actually felt vibrations on their eyeglass frames and teeth fillings.

Are your neighbors having the same problem? Have any of them successfully defeated this problem? I would start a new thread about this one, because it could be interesting. I don't have a lot of experience in limiting EMF, but I'll see what I can dig up.

mm60515 01-19-2008 10:58 PM

Yes all my neighbors have the same problem (except DWV pipes) with the same work-arounds.

goose134 01-20-2008 08:31 PM

Ok, mm, I've talked to a few people and they seem to think that this is what is up. It seems fairly likely that your electrical system at large is responsible for picking up the RFI (radio frequency interference). One guy said that if you install toroidal filters at the mains it should take care of it. Which it would, but I haven't seen them this large before. Even if you were to install these filters on the branch circuits, I'm not sure it would be code compliant or insurance friendly (almost the same thing).
My one friend therefore recommends this: Power strips. I know it sounds too simple to be true, and it may yet be, but many of the better ones have built in EMI/RFI filters. I would buy one that has the highest dB filtering that you can afford and put it on your television/stereo. See if it helps.
He says that the better ones have multi stage filtering. Each stage cuts a bit more of the noise than the last and so on. Keep us posted, this is interesting.

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