Fitting ethernet adapters across phases

[bernardgreen]

The TP Link provides a reference to earth so this isn't an issue.

The bridge cable between two PLC units will have no Earth reference unless there is an Earth reference in one or both the PLC units. Connecting mains earth of one system to the mains earth of another system can result in very high current through the cable linking the earth if there just a volt or two difference between the different mains earth. For this reason data links are isolated from the mains earth and earthed screen in cable are only ( should only ) be connected to earth at inly one end.

Regarding interference, thanks for all the concern, but there are no neighbours here,

An old document but the search and remove activity is still happening ( source is not public domain )
http://www.emcia.org/awareness/Pages/InterferenceExamples/HouseholdAppliances.htm

the TP Link devices are not illegal (afaik)

It is not illegal to own them but it is illegal to knowingly cause interference to radio communication systems. The word "knowingly" provides the authorities with the option to accept the offender's ignorance of the interference they are causing as good reason to not prosecute on a first offence.

 

[Mecca]

rsgaz, thanks. That does answer my question. (And it's good that you did that and then addressed another potential problem I wasn't concerned with so it's good to know about that too.) There is a phone line, and it may go back to the house. Do you mean that I should use spare conductors in that line to run data? Or would I connect the main house router to the guest telephone line using a device of some sort? I can easily run cable from the router to the guest telephone line master socket.

 

[Mecca]

The bridge cable between two PLC units will have no Earth reference unless there is an Earth reference in one or both the PLC units. Connecting mains earth of one system to the mains earth of another system can result in very high current through the cable linking the earth if there just a volt or two difference between the different mains earth. For this reason data links are isolated from the mains earth and earthed screen in cable are only ( should only ) be connected to earth at inly one end.

Got it.

 

[endecotp]

So far nobody has said 'OMG, you can't bridge two phases with a data link' so perhaps it's not something I should be concerned about.

It's not something you should be concerned about.

Just think of all those large businesses and data centers that are full of miles of ethernet cabling connecting thousdands of ports. Do you imagine they all operate on a single phase? Obviously not. The specs for ethernet specifically cope with this by requiring an isolation transformer. (In contrast to, for example, USB, HDMI and other short-range connections.).

Regarding interference, thanks for all the concern, but there are no neighbours here

Then you have less to worry about.

the TP Link devices are not illegal (afaik)

As I understand it, the allegation made against them is that they are only legal because the manufacturers exploit a loophole in the certification process; they demonstrate that the box itself doesn't emit much interference and say that the interference subsequently emitted by the unshielded mains wiring is outside their responsibility. It's not unlike the situation with diesel engines that don't exceed emissions standards in lab tests but do on the road.

This may change; OFCOM are to update the Wireless Telegraphy Act to alow them to require users of interfering devices such as these to stop using them:

https://www.ofcom.org.uk/__data/assets/pdf_file/0020/55307/annex6.pdf
https://www.ofcom.org.uk/__data/assets/pdf_file/0017/58220/statement.pdf

Their statement points out that, for example, in the past they could take enforcement action against a fluorescent light that was causing interference but not an LED light because that wasn't specifically mentioned in the regulations! Now the rules will apply to any "apparatus" at all.

Personally, as an electronic engineer, these products annoy me because my colleagues and I have spent a lot of time making sure that the things we design do comply with the rules. This is difficult and sometimes expensive. Seeing others get away with bending those rules is frustrating.

 

[endecotp]

There is a phone line

I'd try to use that if possible; phone wires are normally twisted-pair (in the UK) so they radiate less.

If you have 4 cores, i.e. if you don't need the actual phone, it might just work without any sort of adaptor at 100 Mbit/s.

 

[Mecca]

I'd try to use that if possible; phone wires are normally twisted-pair (in the UK) so they radiate less.

If you have 4 cores, i.e. if you don't need the actual phone, it might just work without any sort of adaptor at 100 Mbit/s.

Not sure if it's twisted pair. I might get an IT friend of mine in to verify it's OK and set it all up.

 

[jamesmcbride]

Something like this https://www.zyxel.com/products_services/VDSL2-Modem-P-871M/ will enable you to "serve" your own broadband connection over an existing telephone cable.

If there's a cable there at the moment though, are you sure that someone with sufficient experience isn't able to run a cat5 cable between the locations?

To put into context, I've just bought a brand new house and installed over 20 cat6a runs back to a central location with very minimal disruption. Certainly didn't cost me anywhere near £1000 even when you include my time.

 

[Mecca]

Something like this https://www.zyxel.com/products_services/VDSL2-Modem-P-871M/ will enable you to "serve" your own broadband connection over an existing telephone cable.

If there's a cable there at the moment though, are you sure that someone with sufficient experience isn't able to run a cat5 cable between the locations?

To put into context, I've just bought a brand new house and installed over 20 cat6a runs back to a central location with very minimal disruption. Certainly didn't cost me anywhere near £1000 even when you include my time.

This is all useful, thanks. Believe me, if you saw the route between router and the guest house you would understand the cost involved in ducting new cable. Three storey house, flint walls, decorative corbelling, antique coving, York paving around entire house, two drives to cross and a semi underground guest house...

 

[jamesmcbride]

This is all useful, thanks. Believe me, if you saw the route between router and the guest house you would understand the cost involved in ducting new cable. Three storey house, flint walls, decorative corbelling, antique coving, York paving around entire house, two drives to cross and a semi underground guest house...

Fair enough, If you've got a pair, twisted or otherwise, VDSL will probably be the way to go. You can still run voice over it if you need to and AFAIK (haven't tried it, I've only used the same each end) you can use a standard VDSL modem at the CPE end (openreach modem, bt homehub, etc)

I will echo other opinions on powerline adaptors - avoid at all costs

 

[rsgaz]

York paving around entire house, two drives to cross and a semi underground guest house...

Could a catenary wire go between, with some black external Cat5e attached? (spiralled around it to hold it on, never use cable ties,clips,etc)

 

[bernardgreen]

The specs for ethernet specifically cope with this by requiring an isolation transformer.

Invariably two layers of isolation using wound transformers.

Layer one is between mains and the ELV power supplies to the equipment. The transformers have inter winding screens or twin bobbins to ensure mains voltage cannot cross the isolation.

Layer two is between the ELV supplied equipment and the data lines to remote equipment. ( remote being miles away or the next rack )

With PLC units the first layer is often an SMPS which does not offer full isolation of mains to ELV circuits. In some cheaper / counterfeit units the 0v of the ELV is directly connected to Neutral, there is no isolation. If ( when ) the PLC cooks itself then internal damage can result in connection between the data socket and mains.

 

[endecotp]

Something like this https://www.zyxel.com/products_services/VDSL2-Modem-P-871M/

That will do up to 1.5km over a single pair. It's a good solution, and you could keep the second pair for the existing phone line.

But I'd definitely try just wiring the two pairs directly to an RJ45 plug and seeing if it works.