Can I link two ring mains by earth

[Duffledorf]

Hi

I have two ring mains that each have their own consumer unit, but connected to the same meter. I use an Ethernet over power unit that allows me to connect a computer to my router by plugging a unit into the mains at the router and another elsewhere in the house to connect the computer. however, this only works on the same ring main that is used by the sockets near the router. I have been told that these systems use the Earth circuit in the ring main for the Ethernet connection. In the room near the meter and consumer units I actually have an electric socket on each of the two ring mains, I was therefore wondering if it was safe to connect the earth of these ring mains using two standard 13amp plugs and cable connected to earth only.

I would be grateful for your thoughts.

Duff

 

[1john]

all of your CPC's (earths) are going back to a common place so therefore are all joined anyway.

 

[ban-all-sheds]

Not necessarily.

Although 2 circuits within the same house probably do...

Duff - a couple of questions.

1) What do the specs/documentation for these units say about how they communicate?

2) Why don't you put a proper network in?

 

[PrinceofDarkness]

If you have two Cu's, they will (or should be) linked by a common earth conductor, which should be enough for your needs.

The very idea of using a pair of 13A plugs with only an earth connection between them is quite daft.


Lucia.

 

[mikeyd]

I don't think homeplugs use the earth cable for data transmission. As I understand it the data is encoded on the live wires.

If your two consumer units are connected to the same phase then I would have thought it should work, but I wouldn't expect the signal to be as good as if they were on the same circuit.

 

[davelx]

The data is indeed carried on the live conductors and mine work fine between upstairs and downstairs ring finals.

What other equipment do you have plugged in - anywhere? In particular, do you have surge protectors, UPS's - or anything else with heavy filtering inside? Homeplug uses signals between 4.5MHz and 21MHz, so any heavy RF filtering can impact it.

Also if you have electrically noisy appliances connected this will greatly reduce the distance over which it will work.

 

[westom]

I use an Ethernet over power unit that ... . however, this only works on the same ring main that is used by the sockets near the router.

The communication must involve two wires - not just a ring's safety ground.

Numerous devices may 'eat' that ethernet signal. Apparently nothing on the local ring. Probably devices on other rings. One unit notorious from eating these signals are power strip protectors. Many eliminate the problem by removing plug-in protectors and installing one 'whole house' protector. For some reason unknown to me, Leviton units are most often recommended. You may need to install Kieson product.

It gets complicated. That signal eating device may not do so when adjacent to a power over ethernet box. But may do so when distant. Furthermore, it may eat those signals - but not enough to diminish the signal. Multiple devices in tandem may eat enough of the ethernet signal to sufficiently lower the signal to noise ratio.

Yes, signal to noise because some device increase the noise signal. Signal must be so many dBs above noise signals. So you many also be looking for noise generators.

Two problems. Devices that eat signals - lower the signal part of a signal to noise ratio. Or devices that generate noise - increase the noise part of that signal to noise ratio.

 

[Duffledorf]

Hi all

thanks for all the replies and input. It certainly seems that I was on the wrong track in thinking the earth circuit was how the signal was sent, so that invalidates my question anyway, but for clarification the unit is a Powergrid 902 which doesn't give any technical information in the operating instructions. I may be mis-describing the circuit, what I actually have is one consumer unit with a couple of ring mains in the old part of the house and a new consumer unit with ring mains for the new part of the house, the consumer units sit next to each other and the meter. The Powergrid doesn't seem to be able to jump between the two consumer units. The layout of the house makes it difficult to re-cable an ethernet network without major work and because of the layout, the router sits near the front of the house and only provides a weak wireless signal at the back in the new part, OK for audio files, but not for streaming video.

If you are saying that the signal should pass through the two consumer units anyway, I am not sure what would be 'eating' it, I don't have any surge protectors, UPSs connected anywhere, but it is the circuit with all the white consumer goods (fridges/freezers, etc).

My only other thoughts were that maybe I can connect some kind of wireless signal output at the far end of the working ring main to cover the rest of the house. Or instead of of linking the two sockets with earth, what if I had a powergrid receiver feeding into another powergrid sender on the other circuit (or is this another 'the quite daft idea').

Appreciate any further thoughts

Duff

 

[JohnD]

wireless router?

 

[Lectrician]

Or instead of of linking the two sockets with earth, what if I had a powergrid receiver feeding into another powergrid sender on the other circuit (or is this another 'the quite daft idea').

Appreciate any further thoughts

Duff

I think that would work - These devices are 'dumb' and act very simply as if it was a patch lead.

The speed of the connection is not normally the pull 100M, so there is little point in using them if wireless will work for you.

 

[westom]

Appreciate any further thoughts

Available are far more solutions that you want to read.

For example, those two rings could be powered from different phases. Some manufacturers make a device (mounted in the power panel) so that radio signals (and not AC electric) passes from one phase to another.

Wireless - if your WiFi computer does not provide signal strength in dBs, then that is also your problem. Five bars are a useless display so that bosses can think they know what is happening. To make Wifi work, have numbers in dBs.

Many good computer manufacturers provide a program so that computers can report the dB numbers for WiFi. Then you walk about (ie with a laptop) locating where WiFi signals are sufficient and diminished. IOW find what is 'eating' WiFi signals using same principles defined for that 'ethernet on power' solution. (BTW, microwave oven is a WiFi noise generator - as discussed in the previous post.)

For example, in one building. a concrete basement wall across the center of a house caused a massive diminishing of WiFi signals from one first floor router to a computer on the other side. Wall was not even in the direct path and still causes diminished WiFi signals.

In another house, the main heating/ air conditioning supply and return ducts completely wiped out WiFi reception.

In both cases, using dB numbers (always ignore those five bars) resulted in relocating WiFi antennas for reception everywhere in the building.

And then is another concept called access points.

First determine which rings share same power phase and which are on different power phases. Then determine if that causes 'ethernet on power' to appear on some rings and not on others. If yes, then move on to locate one of those signal bypass devices for the power panel.

 

[ban-all-sheds]

First determine which rings share same power phase and which are on different power phases.

It's very unlikely that they will be on different phases - 3-phase supplies for domestic houses are not very common here.

 

[Adam_151]

First determine which rings share same power phase and which are on different power phases.

It's very unlikely that they will be on different phases - 3-phase supplies for domestic houses are not very common here.

But not unheard of, and also in come parts of the country, split phase is quite common

 

[Monkeh]

And then is another concept called access points.

How is an access point 'another concept'?

 

[Duffledorf]

And then is another concept called access points.

Hi Westom

thanks for your input, I assume by access points you mean a wireless transmitter linked to the network?

does anyone know if it is possible to get a plug in wireless transmitter to take the through power signal generated by the Comtrend powergrid device and re broadcast it at another point in the house?

cheers
Duff