seeking how to couple mains circuits for powerline ethernet (EOPL, IEEE 1901)
 

Q1 Can someone tell me how to couple two circuits of my house mains for use of "powerline ethernet" (EOPL, IEEE 1901)?

Even the EOPL Networking vendors trumpet the statement, "coupling boxes must be on the same mains circuit." The coupling boxes adapt the signals from a network cable, typically UTP drop cables. The content is then modulated onto the mains power lines. The gremlin in this deployment appear when the circuit reaches its breaker panel leg and cannot find the other coupling box because it is attached to a circuit on the other panel leg.

It sounds to me like there is some sort of frequency pass-band filter that could enable the EOPL modulation to move from leg to leg without causing mains electrical troubles. Sadly, I've forgotten any knowledge I ever had about how to actually create something like this. I hope that there is some sort of existing product or known-to-work hack other there.

https://www.electronics-tutorials.ws.../filter_4.html

I vaguely remember solving this problem decades ago in the early days of home automation -- X-10(R) or similar. Another vague memory includes a "clothes dryer" plug and connector with some components that spanned the two power connections. This avoided the need to enter and tinker inside the mains panel.

NOTE: I'm working in the USA so our in-house outlets are 120 VAC to a panel that supplies 240 VAC as two separate "legs". The AC power is 60Hz. Half the breakers connect to one leg and one half to the other leg. The term "circuit" typically refers to the same panel "leg" when speaking about EOPL and similar.

Example Mains Panel Wiring

Thank you in advance,
~~~ 0;-Dan

Something like the following?

https://www.amazon.com/SEDNA-Power-P.../dp/B00VV7HYDC

If your carrier frequency is above 1 MHz then no cross-phase coupling is required. The impedance between the phases is low enough that the signal will carry over. The X-10 stuff runs at low frequency so some sort of coupler may be required.

There are no fixed rules, and I suspect vendors say otherwise so that their products are not blamed when used in situations with degraded performance.

The performance of powerline adaptors depends on (apart from the specification/performance of the devices) the attenuation and differential phase delay of the modulated carriers between devices, and the noise at those frequencies, on the path between the devices (mains wiring and connections).

All else being equal, the shorter the path, and the fewer joints in the cable (e.g. mains plugs, wall sockets, distribution boards, junction boxes, extension cables), the better speed you're likely to get.

In the UK it's common for different floors of a house to be on different fused circuits from the distribution board. I've been told by shop salesmen that powerline "just does not work" if the two devices are on seperate circuits, but it simply isn't true. There is still a path between them. Similarly, though it's recommended that the devices are plugged directly into the wall outlet, they will still (likely) work at the end of a long extension lead, it's just that the increased path length and extra junctions will degrade the signal somewhat, and thus potentially (but not necessarily) the data speed.

When talking about RF over copper, cable quality etc., a colleague of mine used to say "A piece of wet string will work if it's short enough". Well, maybe not, but you get the idea.

In practise, the only thing most folks can do when planning to use powerline is to suck it and see. Try it, find out if performance is good enough. Then experiment, keeping in mind that shorter path and fewer junctions are likely to be better. Also, keep it to two only if possible, as a third adaptor IME seriously degrades performance, as they have to share the available bandwidth, discriminate between each other, error correction working harder, etc.



Although USA domestic dwellings have a 120/240Vac supply, it's still single phase (AFAIK). Assuming OP is in a domestic dwelling, it's very unlikely he has a 3-phase supply, so at first look this device would not be suitable. Thinking more about it though, it may be the the case in USA (I don't know) that 120Vac outlets in different parts of the house are on different ends of the 240/120Vac transformer, in which case a coupler of some kind at the distribution board could help. Keep in mind that in USA you'd then be working with a 240Vac potential between the circuits, and with 3-phase in the UK, 440Vac. Advisable to use a qualified electrician IMO.

EDIT: I've read the OP in more detail (as I should have originally, apologies), and now think that something like the device michaelk linked to is highly likely in theory to help the OP get better point to point speeds between powerline adaptors on "Line 1" and "Line 2". That's assuming that the path loss through the coupler is lower than that through the transformer. A coupler designed for 3-phase would involve undesirable but unavoidable losses, and you'd be better with one designed specifically to couple between L1 and L2, with a single LC pass filter rather than three. I haven't seen one after brief search, but they may exist. It might be that the two paths cause phase cancellation, and you'd end up needing an RF choke or ferrite ring in the line from the transformer to get the benefit of the coupler. Again, short of a (moderately complex and so expensive) RF survey, I don't see a better option than to try it and see.

They work best if on same line. In the US we get 240VAC power in the form of two 120VAC lines. From there it goes up to a stepdown transformer. In my case it's a 8,000 volt line transformer to 240VAC.

Now the there are three scenarios. One is PL on same branch. Should tend to work at highest speeds. Now second is across the two. There are various paths that can allow this signal to get from one side to the next. Usually up to transformer but can travel across some few devices in the home.

Here is the last issue. Some house next to you is on same transformer. That means they can connect to your PL.


My house works off power line but I'm the only one on the transformer even if I sometimes have on different branches.

I found this, which may suit your needs. Key thing to note is that it couples PL signals between two mains conductors as opposed to three. As it doesn't divide the signal, it should perform better than a 3-phase coupler in your situation.

https://www.homecontrols.com/homecon...001_Manual.pdf

I do not know if UPB is compatible with Ethernet over powerline or what else maybe inside that particular coupler to know if it will work or not.