Kitz Forum
Computers & Hardware => Networking => Topic started by: Weaver on August 28, 2015, 11:34:49 PM
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If I use double shielded - SSTP or SFTP - cable, can I get away with letting it touch mains cables?
Not lying parallel for a substantial distance.
I got hold of some (hopefully) Cat 6a cable from netshop.co.uk that has an overall foil screen and foil shields around each of the individual pairs.
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I wouldn't worry. It's pretty much going to work or it's not going to work.
If there is too much interference (unlikely) then you'll get significantly slower throughput due to retries etc. MUCH slower than expected. Otherwise it'll just work, and improving the shielding etc won't increase speed at all.
If you look at the reviews of HDMI cables in TV / Hifi magazines, where they say "oh this cable shows much better clarity, detail, colour" etc, it's nonsense. It's digital. it'll either work (= picture) or it won't (= no picture). The fraction in-between will have massive dropout and corruption of picture which will be obvious to all.
Very similar with ethernet.
It works, or it doesn't.
Ian
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I realise I should have said, will any interference get through if using a screened cable? It sounded like a noob question?
[Btw, I know about TCP, all is well (-ish) if you are using it. Of course you may not be., and it's not like you have a choice. In my last job, I was (very briefly) joint Technology Group Leader for the Networking division at what is now known as Symbian (rip). It's difficult on the Internet, as you often don't have any clue who you're talking to. ;D ;D ]
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Actually, could use TCP as an error rate meter. do a fast LAN transfer and see if you can make the speed drop by adding in a possible source of interference. Do it with UTP and then SFTP and compare.
Has anyone ever tried laying UTP next to mains, parallel, to see how much of an effect there is?
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In fact has anyone got any experience of any kind of doing the bad things: mains touching, crossing over at right angles (-ish); or even mains laid parallel ?
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If you look at the reviews of HDMI cables in TV / Hifi magazines, where they say "oh this cable shows much better clarity, detail, colour" etc, it's nonsense. It's digital. it'll either work (= picture) or it won't (= no picture). The fraction in-between will have massive dropout and corruption of picture which will be obvious to all.
An example of what amazes me about these magazines is they still insist that cables are somehow directional, speaker cables have to be connected the right way. :D
Back in the 1970s, when everything was subjective and hence ill-defined, while it had no credibility among those qualified in electronics I'd just laugh at them, and buy the next issue. But nowadays, when their nonsense is so much more quantifiable as nonsense, I begin to despair. :(
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Back in the 1970s, when everything was subjective and hence ill-defined, while it had no credibility among those qualified in electronics I'd just laugh at them, and buy the next issue. But nowadays, when their nonsense is so much more quantifiable as nonsense, I begin to despair. :(
I agree, although with analogue signals, and particularly with below-spec cables, there is an improvement to be had from using at-spec or (maybe) above-spec cables.
Early days of digital TV, I had a digibox connected to an analogue TV with a Scart cable.
The original Scart cable, as supplied, was a bit thin, probably didn't have individual screening between signals. Quality was poor, shadowing on picture, occasional interference.
Replaced with a fatter (but not premium priced) Scart cable that had individual screening (between video and audio signals, for example). Interference went away.
I then wired my own Scart cable with 75 or 50 Ohm (actually can't remember the required spec, but I followed it at the time) cables for video and appropriate for audio. I got a noticeable improvement in video quality and sharpness.
Wanting to go one further, I then bought some "oxygen free" cables etc, getting obsessive about it all. Made up a new cable with the much more expensive wires. No difference.
My conclusion from all this - once you're at spec, you're not going to make it any better.
Ian
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I'm not a believer in the hifi voodoo con stories.
But interference on an ethernet link can corrupt bits and so make packet checksums fail. TCP is not used universally, there are other protocols that do not have retransmissions, so when packets get dropped because their checksums do not check out, then the packet loss is irrecoverable, without some possible kind of application-layer intervention, if available.
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I've always told customers never to run UTP next to mains, not touching in parallel. I think that's uncontroversial, standard wisdom, is it not?
If it's over the top, then I don't care as I just want to _err_ onnthe safe side, and not risk possibly getting any callouts because of network strangeness or mysterious slowness.
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Ridiculous hifi voodoo nonsense claims is an interesting topic, but off-topic for this thread. Should do a split as it's worth discussing. (The huge amount of money charged for such pack-of-lies-based products is big motivation. Two hundred quid for a mains lead, special feet under an amp, that kind of thing. Directional cables have also been mentioned. Utterly bloody ridiculous.)
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I call it 'Magic Science' !
I cannot believe people can still get away with it.
Just check the science on the web.
Very easy to debunk the nonsense.
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Neverthess, getting back to topic, I would be interested to hear of users' experience, and if people are up for a TCP + UTP + mains challenge experiment, then I would love to hear the results.
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If I use double shielded - SSTP or SFTP - cable, can I get away with letting it touch mains cables?
IEE wiring regulations used to forbid anything sharing a route with power cables, for the excellent reason of electrical safety !
I don't see any change in technology to nullify this sensible precaution, can anyone confirm it is still in force ?
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@JGO - I mind you, I am just talking about informal patch cables just laid out however so that mains happens to be beside ethernet cable sometimes. I'm not talking about a structured layout in ducts. When patch cables are lying around they tend to move about as the cats and the occasional human mess around with them. You can't always trust them to stay where they're put and to stay away from mains.
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Where do kitizens get their network cables from? Any good tips for web shops?
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For solid core cable on the reel, I do usually buy cheapest I can find, from a reasonably reputable supplier (say, the likes of screwfix or amazon), that claims conformance to the category I require (cat 5e or better is fine for domestic gigabit). The chances of lying about conformance is small, imho, so one cable reel is as good as another.
For made-up patch cables, I tend to look for branded names. Trouble is, even though the wires inside and twist rates might conform to category there is plenty of scope for manufacturing faults, and cheap and nasty RJ connectors that break. I have had a couple of Amazon cheapie patch cables that were DOA, no continuity on one of the wires when tested.
I seem to recall, when cabling my own home network, that the network adapters on most machines and OS's are capable of reporting how many bad checksums they've seen, though I can't remember off hand how you get at them. Once working I rarely saw numbers other than zero, even after running for days on end. Only exception was when a switch was slowly dying, and I saw error rates soar, which at least confirmed the counters do work.
The adapter on my windows XP, a Dell of about 8 years vintage, has a 'cable test' feature buried away somewhere in 'device manager'. It gives an indication of cable quality, and an estimate of distance to any fault. Again, proved useful when cabling my own, highlighted one dodgy IDC connection (my fault) that otherwise appeared to be working well.
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@sevenlayermuddle - I have always bought Belkin made-up Cat 6 UTP or STP patch cables, but the Cat6 STP ones are very stiff, almost unusably so because they can act as levers where they stick out from a network socket and end up yanking on the socket like a dentist using a lever to pull out a tooth. I also buy patch cables from netshop.co.uk. I only buy Cat 6, or nowadays Cat 6a SFTP cables.
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A TP-Link switch that I used to have had a cable test feature on it if I remember correctly.
Unfortunately the switch went more than a bit weird on me, so I've had to retire it and have gone back to the old Netgear switch that I was using before. Thank goodness I kept the old one around, as it's back in regular duty now, it's just getting a bit old.
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Most of my network cables run with, next to, on top of, cross over eg. all things you should not do :D and I NO have problems with my home network. :)
Re.
IEE wiring regulations used to forbid anything sharing a route with power cables
IEE regs is a recommendation only it's not enforceable. :o
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@tickmike -Well that's good to know from my point of view but not so good for you.
In that case if you can't move the cables which is often not practical then try double shielded patch cables (SFTP cables) from Netshop, Misco, Amazon or wherever. Belkin patch cables are good too. Use Cat 6 or Cat 6a cables if there is any chance at all of you going gigabit, and use ones with good quality metal plugs on the ends snd gold-plated contacts which eill stay clean. That should help a lot, but don't leave things as they are because these problems can be a nightmare to debug and cables only cost a few pounds.
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If it works leave it alone :hmm:
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@tickmike.....can you confirm or deny that you DO or DO NOT have trouble with your network..
and I have problems with my home network. :)
..The smilies in your previous posts may point to you not having trouble with your network.
My 2 lengths of cat5e cable runs alongside main cables for about 6 m (under the landing floor) and I have no troubles at all.
Ian
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What Spectral Bandwidth does Ethernet use ? Does pure 50Hz interfere with it ?
Or is it common practice to have a 1kW spark transmitter as backup for the data link and due to lack of filtering this leaks into the supply http://forum.kitz.co.uk/Smileys/kitzemotes/smiley.gif
What was someone saying the other day about REIN and facing responsibilities ? or does this only apply when other people are causing REIN ?
The point is that if crossing a 50Hz cable causes interference with one data link it may well cause it to others so the source needs dealing with.
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The point is that if crossing a 50Hz cable causes interference with one data link it may well cause it to others so the source needs dealing with.
I completely agree, the trouble is the interference may have a cause over which we have no control, and so may struggle too fix.
An example was a couple of decades ago. My Washing machine appeared to develop an intermittent fault, it worked some days/times but not others. Coincidentally, a bedside clock started to run fast, gaining several hours in the space of a few hours, but only at night. I eventually figured out both had a common cause, an overload of garbage on the mains wiring, that occurred when the street lights came on. An AM radio held near the wiring proved the theory to my satisfaction, and a bigger smoothing capacitor across the clock chip's 50Hz input pin restored clock function.
Getting the street lighting fixed was paramount, but you can imagine the obstacles I encountered trying to get the local power company and authority to even understand my accusations, let alone investigate them. It took months. Meanwhile pragmatic approach was the extra smoothing for the clock, and the washing machine was only used in daytime as I didn't fancy modifying its electronics.
Point being... I have never experienced mains interference on ethernet and suspect it is highly unlikely to occur. But if it does, getting it fixed may not be that easy, and ways may need to be found to live with it...
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I think that I clearly need some more reading matter on this. "What if anything does pure 50 Hz do?" that's a good question. I had only considered mains with lots of harmonics in it.
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@tickmike.....can you confirm or deny that you DO or DO NOT have trouble with your network..
and I have problems with my home network. :)
..The smilies in your previous posts may point to you not having trouble with your network.
My 2 lengths of cat5e cable runs alongside main cables for about 6 m (under the landing floor) and I have no troubles at all.
Ian
Typo :-[ I have NO problems with my home network.
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Getting the street lighting fixed was paramount, but you can imagine the obstacles I encountered trying to get the local power company and authority to even understand my accusations, let alone investigate them. It took months.
Looks like I have street lighting still upsetting my ADSL2 each day through the year, time changes as daylight hours change.
Any tips for getting it sorted.
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Any tips for getting it sorted.
Well in my case, it all predated DSL. The interference was extreme, knocking out a washing machine and a clock, let alone DSL.
The only real clue was that a street lamp right outside the house was flickering a lot, and sometimes on, sometimes off. It didn't bother me in itself but I had a hunch it was part of the problem, so I started pestering the local authority that it was a road safety issue that needed fixed. They responded and, co-incidence or not, the problems went away about the same time that the bad street lamp got fixed.
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Any tips for getting it sorted.
A well known method .......
Do you anyone with a Skip Wagon?
It only takes 5 minutes and is very effective.
:D :D
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Any tips for getting it sorted.
Well in my case, it all predated DSL. The interference was extreme, knocking out a washing machine and a clock, let alone DSL.
The only real clue was that a street lamp right outside the house was flickering a lot, and sometimes on, sometimes off. It didn't bother me in itself but I had a hunch it was part of the problem, so I started pestering the local authority that it was a road safety issue that needed fixed. They responded and, co-incidence or not, the problems went away about the same time that the bad street lamp got fixed.
I think it's the new street lights with 'Electronic ballast' giving out lots of 'mush' over a lot of frequencies because it seems to attenuate a lot of tones and I loose about 6 dB on my 'SNR Margin'
Any tips for getting it sorted.
A well known method .......
Do you anyone with a Skip Wagon?
It only takes 5 minutes and is very effective.
:D :D
Our village would be very dark, just might get a few complaints. ;D
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I think it's the new street lights with 'Electronic ballast' giving out lots of 'mush' over a lot of frequencies because it seems to attenuate a lot of tones and I loose about 6 dB on my 'SNR Margin'
In my own case, I always since suspected that the 'flickering' streetlight was not the cause, rather that it was falling casualty to the interference just as we my washing machine and clock. But in the process of making it work, the underlying problem got fixed.
I should add it was a large new build estate, with several hundred houses added over a three or four year period. It might be conceivable that actually the local supply had simply become overburdened and switching on of street lamps was the straw that broke camel's back?
Voltage was constant and healthy mind, it was only the 'unclean' 50Hz, after street lights came on, that was an issue. Not sure if that blows my theory of overstretched supply out of the water? ???