I wish for wifi access

and all because the OP has his isp router in another room

Having my router in one room and my Pi (and my Mac, but that would work by WiFi happily anyway) in another merely requires off-the-peg ethernet-over-mains beasts, both on the same phase. It was bridging between our LAN and a neighbour’s that wanted a link between phases. We’ve moved now so the whole set-up is gone, but I stand by my assertion that it was perfectly safe: the line between the properties was grounded at both ends through a dozen turns round a ferrite ring (so the signal didn’t leak down that way) and connected to our live wires inside the two properties through capacitors.

If I was wanting to do this – get powerline signals between two different phases – I would be

There are of course numerous options with a DIY approach that may or may not work, so for a change I will suggest the only sensible thing: buy one of those ready-made phase couplers, properly designed and tested for exactly that purpose, that can be safely installed by your trusted electrician.

ready-made phase couplers

Didn’t know any such thing existed! Ethernet-over-mains, yes, but phase coupler? Interesting. I thought our desideratum was pretty unusual. And with a low impedance (except at high frequencies) path to earth at both ends, I really wasn’t worried about my link to my neighbour’s house.

and all because the OP has his isp router in another room

It was I who mentioned having didn’t rooms on different phases. ;)

However, having seen the damage done by a lightning strike to the phone line ¹, I’m strictly WiFi here, even though the reception in the bedroom (technically about five metres away, but over a metre of that is solid stone wall) is lousy.

That being said, I recently gave myself 2×3 sockets in the kitchen by wiring two 3 socket extension leads to a three phase plug, and just tapping off different phases (write-up here).

¹ The phone runs parallel to high voltage (~11kV?) lines for about 300m, I suspect it might have been induced. I notice that the new fibre optic is going to be routed on the other side of the road, even though as far as I’m aware there’s no metal conductor and it doesn’t carry current!

Google found me: https://www.kemo-electronic.de/en/House/Home/M091N-Phase-Coupler-for-Power-Line-Products.php

Probably rather safer than DIYing it!

Probably rather safer than DIYing it!

Undoubtedly, but I really don’t worry about doing intelligent, well-informed DIY. I’ve seen “trusted” (& qualified) electricians do far worse than I’ve ever considered doing.

That’s a German source – so it’s probably good. I’d be more worried about a Chinese one than I’d be about something I’d designed and made myself…

Ah. That’s all very well for your situation, with the three phases colocated. Doesn’t do anything for my connection to my neighbour – I’m not running a live on a different phase from his property into mine to connect to that beast, thanks!

I’ve seen “trusted” (& qualified) electricians do far worse than I’ve ever considered doing.

My god, if this forum had an upvote facility, I’d hack it just to give you a billion upvotes.
The only piece of paper that isn’t mostly worthless is the insurance registration number.

Doesn’t do anything for my connection to my neighbour

For that, you probably want some sort of WiFi bridge. You can get things on Amazon that are outdoor mounted boxes with a parabolic antenna. You buy them in pairs and point them at each other… however it falls into the category of “Cheap Chinese Crap” so…

I discovered these yesterday while looking to see if I could get an outdoor WiFi repeater to give better coverage in the garden, with the specific requirement that there not need to be any wired connection (well, the Vonets can do it). A lot of Chineseries there, with some… interesting comments in the user reviews, like “must create an account to be able to use the thing” (WTF?) and “the IP address is fixed at 192.168.10.1” (WTF²?) and so on.

For that, you probably want some sort of WiFi bridge.

I really was quite happy with my bit of wire, safely earthed at both ends except at high frequencies.

If the capacitor to live at either end had gone short circuit, the corresponding RCD would have tripped. Never happened, that set-up ran happily for just over five years. Dismantled when we sold the house, of course – just over a year ago now.

Any electrician breaking out in a sweat over the capacitor hookup, please allow me to point you at the idea given in the scan at the bottom of this blog article: https://heyrick.eu/blog/index.php?diary=20180314&keitai=0
It’s a real scan from a real book.

ROFL

Electricians might break into a sweat, but if so, they just don’t understand either the set up, or some pretty basic physics. Either of which is entirely possible, nay reasonable: their training and qualification aren’t designed to prepare them for assessing such a design or implementation.

ROFL.
I don’t think there’s any training or course that would make that ever seem like a good, logical, nay even halfway reasonable idea.

Hmm, I wonder how it actually behaves. A small load to gently sizzle, or something that’ll blow fuses? I guess it might depend upon the water content of the sausage…

Indeed. I think we’re talking at cross purposes a bit. I meant my set-up, not yours.

I doubt yours would blow fuses (or trip MCBs or RCDs) – and as long as its done on a suitable surface, and switched on (and off again) remotely, a perfectly safe experiment to do. I don’t think I’ll bother though – although I’ve done equally weird things in schools and colleges as experiments and demonstrations for educational purposes.

Oh, right. I thought you meant the sausage thing.

My setup relies upon particular aspects of quantum fluctuations, best expressed as “this shouldn’t work, but…” and “this wire is in an indeterminate state until you touch it”.
Doesn’t do to peer too closely at the abyss.

I’ve seen “trusted” (& qualified) electricians do far worse than I’ve ever considered doing.

My god, if this forum had an upvote facility, I’d hack it just to give you a billion upvotes.

I’ll see your billion and raise.

please allow me to point you at the idea given in the scan at the bottom of this blog article:

What size sausage could a PP3 cook? Or do you think something like a cocktail sausage is more in the PP9 range?

Any electrician breaking out in a sweat over the capacitor hookup,

“electrician”?

please allow me to point you at the idea given in the scan at the bottom of this blog article: It’s a real scan from a real book.

There’s an obligatory Big Clive for that one: Turbo charging a 120V Presto hot dogger on 250V — and a quick hunt around his channel will reveal many other similar experiments, both with the hot dogger, some “special electrical forks” (IIRC) and a rather delightful set of eBay-sourced water boilers.

You posted two hours ago. I’ve spent those two hours watching his videos (and, wow, that ioniser with the mains on the output!).

So, we’re actually supposed to measure Power Factor in Frankenfurters? Good to know these things

When he said the PF was 1 because it is a resistive load, I very neatly lost my tea.

A little off topic.
Old hat. In the “National People’s Army” of the GDR, immersion heaters, kettles, etc. were forbidden in the living room.
Necessity is the mother of invention and so there was the model shown in the scan with the cutlery, forks for heating sausages and so-called “UFO’s”… Two washers or razor blades with a separating layer made of plastic (usually the transparent discs of the breathing masks) for heating water.

Youtube didn’t exist when I was there ;-)

P.S: The picture is from the Military History Museum and was confiscated in 1988 during a room inspection. ;-)

That’s not off topic at all, Raik! Spot on.

As for a sausage constituting a resistive load…hmmm…I’m almost tempted to do some experiments, but I suspect its characteristics are nearer to those of an electrolytic cell, which is most definitely NOT a resistive load…

Youtube didn’t exist when I was there ;-)

Our stuff was a bit more primitiv but…

https://m.youtube.com/watch?v=2Kynts3xoek

…for the “Frankfurter” and

an “UFO” or “Atomino” you find here

https://youtu.be/IZYZLq1s3ts

Round about after 45s.

For the kids…never imitate! ;-)