Grounding a shielded ethernet cable

[MECHENG84]

I’m about to run a 2nd router as an access point in my house. I’m connecting it to the source router via a shielded cat5e cable as it runs next to an aerial cable so I want to minimise interference, it’s about 20m long. I can’t seem to find out if all routers (or at least the routers/devices I’m using) will definitely ground shielded cables. The 2 items being connected are a BT home hub 5 and a coredy AC1200. I’ve contacted coredy but no response and BT also unhelpful. I have also heard that only 1 end needs to be grounded. Does anyone know if either of these devices will ground a shielded cable?

[anonymous-user]

Your cable will have aluminium foil shielding under the outer sheath. It may also have a drain wire (a thin silver wire along side the aluminium foil shielding).

Somthing like this , most likely without the individualt shielding of each pair.



If you have the drain wire, earth this at one end.

As you are not using pro or outdoor gear, your routers won't have an earthing point (metal screw into square metal plate, marked with the Earth symbol). You will need to find your own earth. Easiest is a copper rad pipe. (your routers are both powered by 12v power adapters, so are not earthed anyway!)

In my installation I have an outdoor AP (CPE) and an indoor router that is 50m away. I earth only the indoor drain lead. I extended it with a screw block and some standard single core cable to inside the mains trip switch box (consumer unit) and connected to the earth rail.

Your cable running along a TV antenna wire won't cause any issues, and a drain wire / earthing won't make any difference with RF interference - that's the job of the tin foil layer.. IF you run the cable outside then you need to seriously think about earthing one end of the drain wire so transient electricity from electrical storms has somewhere to drain. This is why you don't connect both ends - you want the spikes to go somewhere, not everywhere.

p.s. the grounding you speak of doesn't happen in the 8 pins of the network plug. It's in the drain cable as above.

Edited by anonymous-user on Thursday 25th July 15:48

[MECHENG84]

RogerDodger said:

Your cable will have aluminium foil shielding under the outer sheath. It may also have a drain wire (a thin silver wire along side the aluminium foil shielding).

Somthing like this , most likely without the individualt shielding of each pair.



If you have the drain wire, earth this at one end.

As you are not using pro or outdoor gear, your routers won't have an earthing point (metal screw into square metal plate, marked with the Earth symbol). You will need to find your own earth. Easiest is a copper rad pipe. (your routers are both powered by 12v power adapters, so are not earthed anyway!)

In my installation I have an outdoor AP (CPE) and an indoor router that is 50m away. I earth only the indoor drain lead. I extended it with a screw block and some standard single core cable to inside the mains trip switch box (consumer unit) and connected to the earth rail.

Your cable running along a TV antenna wire won't cause any issues. IF you run the cable outside then you need to seriously think about earthing one end so transient electricity from electrical storms has somewhere to drain. This is why you don't connect both ends - you want the spikes to go somewhere, not everywhere.

Thanks for this, Looked into it a bit more earlier and your comment pretty much confirms what I'd managed to find out. No metal around RJ45 jacks in devices so they're not going to earth the cable. The coredy is one of those little units that plugs straight into a 3 pin plug. Fortunately it's being plugged into a Twin socket, So I'm going to solder a wire coming off the RJ45 shield (rather than have to cut the end off and extend the drain wire then re-crimp) terminate the drain wire to the earth pin in a standard 3 pin plug and plug it in next to the coredy....if that makes any sense.

[anonymous-user]

You really won't need to do it for internal cables.

[NorthDave]

MECHENG84 said:

Thanks for this, Looked into it a bit more earlier and your comment pretty much confirms what I'd managed to find out. No metal around RJ45 jacks in devices so they're not going to earth the cable. The coredy is one of those little units that plugs straight into a 3 pin plug. Fortunately it's being plugged into a Twin socket, So I'm going to solder a wire coming off the RJ45 shield (rather than have to cut the end off and extend the drain wire then re-crimp) terminate the drain wire to the earth pin in a standard 3 pin plug and plug it in next to the coredy....if that makes any sense.

That has way more potential for issues than just not bothering.

The aerial lead will cause you zero issues. I think you are over complicating this and I would recommend no grounding at all over such a short distance (and indoors).

[TonyRPH]

Upon reading the OP this was my first thought.

[sjj84]

What are you running, NASA? Totally unnecessary, just run a cat 5 like everybody else, it won't cause you any problems.

[MECHENG84]

TonyRPH said:

Upon reading the OP this was my first thought.

Overthinking everything and expecting everything to fail or cause problems is a hazard of 15 years in my job.

This cable will technically be outside some of the route. It's coming from the loft, through the eves and down the side of the house and then through the wall into the dining room.

Though that wasn't my concern, more the ethernet cable causing EMI interference with the RF signal on the aerial. I'll just run the cable and see how I get on. I'll ground it at a later stage if I need to.

[MECHENG84]

sjj84 said:

What are you running, NASA? Totally unnecessary, just run a cat 5 like everybody else, it won't cause you any problems.

No this isn't for NASA my house, coincidentally though I've done work for NASA in the past and I do design everything even in my house as if it was for industry.

[Evanivitch]

MECHENG84 said:

Overthinking everything and expecting everything to fail or cause problems is a hazard of 15 years in my job.

This cable will technically be outside some of the route. It's coming from the loft, through the eves and down the side of the house and then through the wall into the dining room.

Though that wasn't my concern, more the ethernet cable causing EMI interference with the RF signal on the aerial. I'll just run the cable and see how I get on. I'll ground it at a later stage if I need to.

So then why would you take the risk of making unauthorised modifications to the build standard and invalidating the CoC?

[MECHENG84]

Evanivitch said:

MECHENG84 said:

Overthinking everything and expecting everything to fail or cause problems is a hazard of 15 years in my job.

This cable will technically be outside some of the route. It's coming from the loft, through the eves and down the side of the house and then through the wall into the dining room.

Though that wasn't my concern, more the ethernet cable causing EMI interference with the RF signal on the aerial. I'll just run the cable and see how I get on. I'll ground it at a later stage if I need to.

So then why would you take the risk of making unauthorised modifications to the build standard and invalidating the CoC?

It's my house so I can make whatever mods I wish to, I'm the boss! You can actually buy the RJ45 plugs that do what I want to do ready made:



The cable doesn't have a CoC.

It's about the physics of whether something will work or will not.

[Mr Pointy]

Of vastly more importance than grounding the screen is that you use an exterior grade cable & make sure there's a drip loop at the bottom end.

[MECHENG84]

Mr Pointy said:

Of vastly more importance than grounding the screen is that you use an exterior grade cable & make sure there's a drip loop at the bottom end.

I'm running it in conduit for the outside section, so not overly concerned about drip loop and using exterior graded cable, if it degrades and needs replacing in 5 years time then I'm not going to be too upset. it's a good point to make though.

[TonyRPH]

MECHENG84 said:

Mr Pointy said:

Of vastly more importance than grounding the screen is that you use an exterior grade cable & make sure there's a drip loop at the bottom end.

I'm running it in conduit for the outside section, so not overly concerned about drip loop and using exterior graded cable, if it degrades and needs replacing in 5 years time then I'm not going to be too upset. it's a good point to make though.

I have got four lengths of standard CAT5E cable strung between my house and garage (a 4M span) and they've been there for about 6 - 7 years exposed to all the elements, with no degradation, amazingly enough.

Conduit and exterior grade cable should last for ever on that basis!

[WinstonWolf]

MECHENG84 said:

TonyRPH said:

Upon reading the OP this was my first thought.

Overthinking everything and expecting everything to fail or cause problems is a hazard of 15 years in my job.

This cable will technically be outside some of the route. It's coming from the loft, through the eves and down the side of the house and then through the wall into the dining room.

Though that wasn't my concern, more the ethernet cable causing EMI interference with the RF signal on the aerial. I'll just run the cable and see how I get on. I'll ground it at a later stage if I need to.

If you want to overthink it use a proper AP rather than a router

[MECHENG84]

WinstonWolf said:

If you want to overthink it use a proper AP rather than a router

I did overthink about that. For my budget, the BT home hub (can't remember which version) has en extremely good wifi chip and broadcast range and is very easy to configure to use as an AP, I picked it up 2nd hand for £10. An equivalent dedicated AP with same specs was over £100 .

[MECHENG84]

TonyRPH said:

I have got four lengths of standard CAT5E cable strung between my house and garage (a 4M span) and they've been there for about 6 - 7 years exposed to all the elements, with no degradation, amazingly enough.

Conduit and exterior grade cable should last for ever on that basis!

Reassuring, I'm not using the outside graded cable but the fact you've got 6 -7 years with no conduit puts me in a good position .

[anonymous-user]

Someone will be here soon telling you to "use cat 6e - think of the future!" you might run a server farm - you never know! :-p

[eliot]

Shielded cable unnecessary and may cause problems trying to ground it. Twisted pair cables are inherently immune to interference.

What is far more important is making sure you are getting pure copper cat5 or 6 - the vast majority of cables on ebay are copper coated aluminium (CCA) which as the name suggests is made from aluminium not copper and isn’t certified for any CAT standard at all.

[Mr Pointy]

RogerDodger said:

Someone will be here soon telling you to "use cat 6e - think of the future!" you might run a server farm - you never know! :-p

Don't be silly.

It needs to be fibre

Edited by Mr Pointy on Friday 26th July 16:00