A quick European wiring puzzle with a simple answer

Lucien Nunes · Dec 17, 2021

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!

[ElectriciansForums.net] A quick European wiring puzzle with a simple answer

DPG · Dec 17, 2021

Making local sockets TNC?

Lucien Nunes · Dec 17, 2021

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

Vortigern · Dec 17, 2021

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 · Dec 17, 2021

Lucien Nunes said:
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 · Dec 17, 2021

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

Lucien Nunes · Dec 17, 2021

@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 · Dec 17, 2021

Lucien Nunes said:
@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 · Dec 17, 2021

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 · Dec 17, 2021

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

timhoward · Dec 17, 2021

Is it a transformer?!

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

Lucien Nunes · Dec 17, 2021

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

DPG · Dec 17, 2021

Socket outlet and trailing plug?

Lucien Nunes · Dec 17, 2021

Yes, what kind and function?

Mikegh · Dec 17, 2021

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

Petej999 · Dec 17, 2021

Lucien Nunes said:
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!

View attachment 93075

Seen lots of stuff like this in the three years plus vI spent working and living in the former USSR during the mid 1980s

timhoward · Dec 17, 2021

Lucien Nunes said:
Yes, what kind and function?

Wild guess - back of a schuko socket?

DPG · Dec 17, 2021

timhoward said:
Wild guess - back of a schuko socket?

The wiring of the plug appears to come straight out of the bottom though. Cant picture what sort of plug that is.

Reminds me of one of the 8 pin Bulgin 'disco light' connectors - am I close Lucien?

Lucien Nunes · Dec 17, 2021

It's not Schuko but it's derived from that. It's not got 8 pins like the Bulgin but it has got more than 3.
Domestic / light commercial usage. Available in 16A and 25A versions.

timhoward · Dec 17, 2021

??
(cross post, sorry, I did post before I saw yours!)

Dustydazzler · Dec 17, 2021

3 phase and n

or

2 phase and n

Lucien Nunes · Dec 17, 2021

TP+N or sometimes cheekily 2P + 2N (not an official configuration but used today)

And it goes by the name of...?

DPG · Dec 17, 2021

I like the look of those.

timhoward · Dec 17, 2021

Lucien Nunes said:
TP+N or sometimes cheekily 2P + 2N (not an official configuration but used today)

And it goes by the name of...?

Perilex I think

Lucien Nunes · Dec 17, 2021

@tinhoward you win this round, 16A Perilex, often used as a cooker plug in domestic 3-phase installations that are common in mainland Europe. 3x16A = equivalent to 48A single phase so plenty of juice for any kind of cooker. Increasingly though, where you have a single-phase oven, and a hob that can use 2 phases out of 3, Perilex gets used on single-phase installations with two line pins and two neutral pins. A bit naughty, I've seen it done with either L1 or L3 as the second neutral, usually marked on the front in sharpie.

The 25A version is not as widely used, the two are distinguished by the orientation of the flat, central earth pin, horizontal = 16A, vertical = 25A.

I like them too although the contacts on some of the basic sockets are not as well engineered as many Schuko sockets of the same rating.

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