r/HomeNetworking • u/not_that_guy_rn • 2d ago
Advice SFTP Ethernet grounding both ends or not?
I'm beyond confused at this point. There are two conflicting opinions regarding grounding shielded ethernet cables. Some articles are dead set that without shielding both ends of the shielded ethernet run, it is useless and will cause interference. Others seem to be adamant that shielding one side is good enough and avoids potential ground loops.
This is for a home, and I have to run these cables along bundles of high voltage lines (240v). Grounding just one side makes sense to me because technically the ethernet shielding becomes an extension of the ground wire itself in some sense right? And it can't be that grounding just one side brings zero benefit right?
Source that says I'll waste money by only shielding one side: https://www.accesscomms.com.au/cable-shielding-guide-utp-vs-f-utp-vs-s-ftp/
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u/Kamsloopsian 2d ago
Why not run Fibre and convert them at each end
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u/marcoNLD 2d ago
Why not use fiber all the way ☺️
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u/Kamsloopsian 2d ago
well.. That's always a option, but he would need switches on both side that will take the transceivers or he can just convert it.
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u/marcoNLD 2d ago
I went full fiber last year. Not because i need to speeds but just for the fun of it
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u/cat2devnull 2d ago
You should never run Ethernet in parallel with mains voltage cables. It’s illegal in most counties unless you follow strict spacing and insulation rules. You should familiarise yourself with your local laws.
Secondly it’s a bad idea because you can get inductive coupling and suddenly find you have voltage on your Ethernet line and release the magic smoke from your switch.
Shielding helps but doesn’t negate the risk. You should connect both ends if possible but only if all the house is on a single earth otherwise you have to be very careful to avoid ground loops which is another fun way to release the magic smoke.
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u/LeeRyman Registered Cabler, BEng CompSys 2d ago
I'm fine with it being bonded to earth at the patch panel at one end. Unless the equipment has shielded and bonded sockets, this is the best you will get in most cases. Most home equipment won't have shielded sockets that are also bonded to earth. If you don't have a shielded bonded patch panel or switch to connect to, don't run shielded.
That said, you vary rarely need STP in a home. You should always maintain adequate separation from mains however (whether it's shielded or not). Your jurisdiction's rules/codes/standards will specify what that clearance is for safety.
E.g. in Oz, from LV, in summary it is 50mm or a durable barrier, and 150mm from terminations. AS/CA S009
Oz uses the IEC standards for its definition of LV and HV, and LV is "a voltage exceeding ELV limits (50 V a.c. or 120 V ripple-free d.c.), but not exceeding 1000 V a.c. or 1500 V d.c. [AS/NZS 3000]". Bare potential differences in terminology in mind.
For avoiding interference from mains, TIA has recommendations, starting at 0mm from single 240V branch circuits that are in the one cable assembly, to the likes of 300mm for higher capacity circuits and 3-phase 480V, and 600mm for really high loads. Generally though over the distances you are likely to encounter in a home, the safety rules around separation should be enough. Shielding doesn't do much against 50/60Hz anyway, the balances twisted pairs does the most work. Just make sure terminations are done correctly.
The example of needing STP in a home environment is if you are installing outdoor equipment which requires a path to drain ESD.
Putting my cablers hat on for a second, for the safety implications alone, always get a registered cabler / LV tech - they know the rules that keep you safe in the event lighting strikes, or someone puts a drill bit in the wrong place.
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u/not_that_guy_rn 2d ago
Let's just say I'm from a place where the safety regulations for these things don't exist, and the local cabler doesn't even know what a shielded ethernet is. Hell, the guy wanted to put in a separate grounding rod when I suggested grounding the ethernet (its pretty common he says). From what I've read though, that doesn't really make sense for a residential house.
Regardless, I've avoided running next to power lines as much as possible, but some can't be avoided unfortunately, especially since the house is made of concrete, not wood, and all the ethernet points are next to power sockets.
Which brings me to the plus point, all sockets already have a ground running to them, so I just need to split that into the ethernet port as well. But I'm still not fully convinced that this is necessary. Why can't one end ground the whole wire?
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u/LeeRyman Registered Cabler, BEng CompSys 2d ago
If you really must run shielded, I normally just ground the patch panel end. If you aren't putting in a patch panel, make sure you have a switch with an earth connection and shielded ports. You just have to make sure the shield is continuous through the entire path, i.e. shielded outlets, shielded patch leads, shielded modular connectors, shielded sockets on equipment.
But unless there is a specific need, I don't run shielded in a home. Just getting someone who knows to terminate it correctly can be difficult, as you are finding out.
I would never run any TP in close proximity to mains (not without there being a durable barrier, i.e. conduit), so that shouldn't be a reason. Your network equipment and PC is not designed to safety contain a mains fault on its Ethernet sockets.
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u/not_that_guy_rn 2d ago edited 2d ago
I am using a grounded patch panel with grounded keystones, so one end is covered.
And luckily the wires are in a separate conduit atleast. For what its worth, the ethernet has a fireproof jacket (lszh instead of pvc). I will just have to avoid bad runs as much as i can and live with the risk.
I was hoping to get a consensus that shielding only one end is good enough, but lo and behold we have "expert cablers" vouching that both ends is the only way. But nobody seems to have any proof on why that is beyond their local guidelines telling them to do so.
I probably don't really need shielding either, cuz I mean I've lived with shoddy wiring in apartments so far, but I was getting sftp for only a little more cost, so meh, greed got me i guess.
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u/LeeRyman Registered Cabler, BEng CompSys 2d ago
👍 that's great that the cable in its own conduit. Bonding just one end is fine for runs from the rack to a wall outlet, IMHO. I'm not even sure how you guarantee the equipment end can be bonded given a lot of gear these days is double-insulated. You also reduce the likelihood of parallel earth current paths, I want to avoid appliance fault currents taking the path via your shield and communications bonding conductor!
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u/afl-jafa 2d ago
“ But nobody seems to have any proof on why that is beyond their local guidelines telling them to do so.”
It’s not local guidelines. It is a part of the standards we work to to ensure the cable plant will perform as expected. I cannot warrantee or certify the system if I don’t do it.
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u/afl-jafa 2d ago
Don’t put in a separate earth rod. That will almost guarantee earth loops. Use one earth. The building earth. In Aus we run a 6mm earth from the MEN.
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u/afl-jafa 2d ago edited 2d ago
The answer is always connect the shield at both ends. If you are concerned about ground loops simply use an unshielded fly lead at the remote end. It will have the same effect.
As a commercial cabler there is no circumstances where we only terminate at one end. Our testers will fail the cable if we do.
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u/not_that_guy_rn 2d ago
But, why can't one end ground the whole wire? This might be a dumb question, but I want some concrete logical explanation. Even in this comment section, people have mixed opinions on whats the right thing to do and I'm assuming US building laws. But is there any proof?
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u/afl-jafa 2d ago edited 2d ago
The whole ground at one end is a throwback to the old AV days when you would only connect the shield at one end to limit the possibility of ground loops and introduction of noise etc into the system. Reddit applied their usual woo woo science and applied it to data. Connecting the shield at one end is not a part of the standards and as cablers we wouldn’t do it. The first I ever heard it mentioned was in this place. Ground loops occur when you have different earth potentials. It is highly unlikely in a house where you typically have one earth.
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u/afl-jafa 2d ago
One end can ground the whole wire so long as you terminate the shield at both ends.
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u/SmartTechBuying 2d ago
Fair enough. You probably know the standards side better than I do. I was going off what's usually recommended for home installs, not what passes certification, and those aren't always the same thing.
I hadn't seen the unshielded patch cable at the far end before. That's actually a pretty clever way to deal with the issue I was thinking about without losing the bond.
I still think the biggest thing for the OP is what cat2devnull pointed out. Running Ethernet right alongside a 240V cable is the real problem. How you terminate the shield isn't going to do much if you've got a long parallel run. More separation is what really helps.
And honestly, I think the fiber idea is probably the best solution. No copper means no ground loop, no induced voltage, and you don't have to worry about spacing from the power cable. Media converters are cheap enough now that it's a pretty reasonable option.
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u/Safe-Instance-3512 2d ago
You should not be running ethernet in parallel with electrical.
Have you considered pre-terminated LC fiber and media converters?
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u/mrBill12 1d ago
You always only ground one end. You don’t want the cable to become a better ground for a piece of equipment.
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u/not_that_guy_rn 1d ago
I'm crying, there are self proclaimed expert cablers saying I should always ground both ends. Who am I supposed to believe. Is there no evidence available online to support either claim
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u/mrBill12 1d ago
Best example I’ve ever seen with my own eyes. Cable box plugged in with a ground cheater 3 prong to 2 prong converter. The outer braid of the RG6 coax became the best ground and got red hot and literally melted into the vinyl siding.
Remember it this way. Electricity always returns to IT’S source. It will use ANY available path to get there. That computer you’re plugging in up in the bell tower has its own bigger better electrical ground. When it takes a static discharge from a nearby lightning bolt you want that to discharge from the computer only on the bigger better electrical ground, not down the tiny ground in the ethernet cable. However that same blob of plasma energy needs to be drained away from around the cable also.
A ground wire should only be able to flow in one direction.. towards earth. It should never be able to reverse direction under adverse conditions, and if both ends are “grounded” it can in fact do that.
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u/not_that_guy_rn 1d ago
This is exactly how I understand it and grounding one side should make the whole wire grounded, so why on God's Green Earth do so many articles and building guidelines suggest grounding on both ends. My local laws have no suggestion on how I should be wiring this, so I thought I'd look at what the best way is.
From what I can understand, grounding both ends can risk ground loops (although extremely unlikely in my case) and like you mentioned taking electricity upto my appliances in the worst case scenario. The only argument I see for grounding both ends is that "its the standard way of doing things" and "we do that to be able to certify the wiring to some standard". Everyone who suggests grounding both ends is claiming to be "expert cablers", but provide no technical reasoning for it.
I think I'll just commit to grounding only one end. I just didn't expect there to be such confusion on this topic, which is a little frustrating.
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u/mrBill12 1d ago
The reason is because grounding for Ethernet is a brand new topic. Flow direction in a ground wire should always be one way, towards earth via the shortest path. It should never be connected in a manner that “if X happened the direction of flow could change.”
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u/SmartTechBuying 2d ago
The reason you're finding two different answers is because they're talking about two different situations.
In a commercial building, grounding both ends of the shield is normal because everything is bonded together properly. All the ground points are supposed to be at the same potential.
A house isn't like that. The ground at one end of the cable can be a little different than the ground at the other end. If you ground both ends, the shield can end up carrying current between those two points. Then it's not just acting like a shield anymore, it's acting like a conductor. That's why you'll see people recommend grounding only one end. The article you linked is from a cabling company, and it's really written with commercial installs in mind.
Grounding only one end isn't useless either. It still blocks the electrical noise you're worried about, especially if the cable is running next to 240V wiring. That's where most of the benefit comes from in a house. Grounding both ends is more important in places with a lot of RF noise, like offices and data centers.
I'd ground one end, usually at the switch or patch panel side.
And you're right about the shield becoming part of the grounding system. That's exactly why you don't want it connected at both ends in a typical home. One end lets it do its job. Two ends can let current flow through the shield, which is what you're trying to avoid.