A quick European wiring puzzle with a simple answer

[Lucien Nunes]

Following from a recent thread mentioning some continental electrical practice, I made this mock-up of something you might see in an older installation in a certain West-European country. It's not standard practice now but is widespread enough to have a specific name. What is the name of this specific circuit arrangement in the local language? Not sure if we have any sparks from the country in question on here but please let the Brits have a try!

 

[DPG]

Making local sockets TNC?

 

[Lucien Nunes]

Yes, crazy though that might seem to us
And it's called?

 

[Vortigern]

Klassica Nullen Germany? I think this was done in Finland and Austria as well as visegrad countries about forty years ago.
Maybe klassische Nullung

 

[DPG]

Yes, crazy though that might seem to us
And it's called?

Don't know the name. Although I might if I heard it.

 

[Dustydazzler]

Quite a lot of older American / Canadian installs have a grounded neutral / neutral combined ground , basically a bootleg PME

 

[Lucien Nunes]

@Vortigern you win. Klassische Nullung. And very popular indeed in Finland until quite recently (was it 2001?) where a CNE conductor was often of larger CSA , I think they were the last to forbid it. And @Dustydazzler yes in the USA it's called a bootleg ground and is deprecated; their preference for grandfathered 2-wire circuits is to enforce retrospective 5mA GFCI installation and leave the EGC / ground terminal disconnected.

My mockup shows an example of an old installation with no CPC in the original black/grey section dating from the 1950s. In 1969 it became standard to run 3-core cable to new points, with a blue neutral and green/yellow CPC, but it was permissible to connect both to the existing grey neutral.

I first met this in 1987 when I was tasked with putting up a fluorescent batten in premises with a 2-core lighting circuit. The local electrician told me to link the CPC and N terminals in the fitting which seemed like the weirdest thing at the time but I got used to it. Couldn't resist checking as many upstream neutral terminals as I could in the available time, to ensure there wasn't something about to drop off and send the fitting live. The workmanship was good and I couldn't see any likely problems. No RCD of course then.

OK next.
Name and usual application of this (upside down) accessory?

 

[DPG]

@Vortigern you win. Klassische Nullung. And very popular indeed in Finland until quite recently (was it 2001?) where a CNE conductor was often of larger CSA , I think they were the last to forbid it. And @Dustydazzler yes in the USA it's called a bootleg ground and is deprecated; their preference for grandfathered 2-wire circuits is to enforce retrospective 5mA GFCI installation and leave the EGC / ground terminal disconnected.

My mockup shows an example of an old installation with no CPC in the original black/grey section dating from the 1950s. In 1969 it became standard to run 3-core cable to new points, with a blue neutral and green/yellow CPC, but it was permissible to connect both to the existing grey neutral.

I first met this in 1987 when I was tasked with putting up a fluorescent batten in premises with a 2-core lighting circuit. The local electrician told me to link the CPC and N terminals in the fitting which seemed like the weirdest thing at the time but I got used to it. Couldn't resist checking as many upstream neutral terminals as I could in the available time, to ensure there wasn't something about to drop off and send the fitting live. The workmanship was good and I couldn't see any likely problems. No RCD of course then.

OK next.
Name and usual application of this (upside down) accessory?

View attachment 93082

It's not one of the larger type of foreign telephone sockets is it?

 

[Lucien Nunes]

Connect telephones to that at your own risk. Likely to go up in smoke.
Note I've put the cutters there to hide some markings but I left an important feature visible.

 

[DPG]

I reckon you can see a strain relief boot and maybe a cable grip. So it's a trailing socket of some sort.

 

[timhoward]

Is it a transformer?!

And that wasn’t long enough so ding ding merrily on high to the new character limit….

 

[Lucien Nunes]

It's two things fitted together, lying with the back of one of them uppermost. There are mounting screwholes in that part.

 

[DPG]

Socket outlet and trailing plug?

 

[Lucien Nunes]

Yes, what kind and function?

 

[Mikegh]

Interesting and it seems an odd practice

You'd nearly have to a risk assessment for each case to see is worth connecting the return wire to exposed metal