Anyone ever come across a neutral using the earth on purpose?

[captaincaveman]

Just interested in peoples thinking on using the neutral through the earthing system like I came across today. I've come across many wrong polarities tripping mcbs before but not this.
The outside front door light live conductor was wired into the lightswitch inside but the neutral was wired into the metallic switch earth terminal - thus using the earth as the neutral. Obviously the light bulb itself was stopping a short circuit which is why it had been used for considerable time without blowing the rewirable fuse I'm just wondering if there is a scenario, other than a break in the earth, where someone could get a shock through this setup? excuse my absent-mindedness as this job has been a nightmare!

• The bathroom timer fan permenant live was a cpc (from the kitchen downstairs!),
• The kitchen lights neutral was connected to / going through the socket circuit neutral!
• The garage power, spurred from an outside socket [unglanded / failing ip] which itself was a spur off a spur, failed IR tests. The outside socket was also feeding a dozen normal/indoor extention leads on the patio
• The outdoor lights (except the front door one, above) were using CPCs as live conductors and some of them were even cabled in what looks like data cable!

I could probably go on all night.... Some jobs just make you want to cry lol.
Incidentally, the customer admitted wiring the neutral into the cpc for the front door. In his words - "I just did trial and error until the light came on"
I need to start writting note for my memoirs lol

 

[Dave OCD]

Regarding the light switch, if it's a TNCS earthing arrangement then it would work fine without bothering any fuses, but it would become a problem as soon as an RCD is fitted, very very dodgy though.

 

[James]

I know a guy, obviously not myself who has used L1 and the nearest earth to power his laptop to program machines with no neutral available.
must have used a relative of the seal fairy!!

 

[plugsandsparks]

Come across this twice, once domestic and once industrial. The domestic one was spotted when i changed the board and upgraded to RCDs... lol - The industrial one was done by an installer of a induction furnace heater who could not wait for a TP+N supply to arrive and connected to a TP only using E for N... eeekkk, was not impressed with that one

 

[littlespark]

Must be done more often than we know about.

I’ve spoken before about my neighbours flooded house that ended up getting a new board fitted.
Original board, the lights were not on rcd. New board they were.
Whoever put the outside light up originally managed to shear the neutral with fixing holes… so quietly used the cpc for neutral. Would never have been know otherwise.

 

[SparkySy]

I have an engineering customer who had several machines that had been altered to allow for new drives and sockets for ancillary kit on them. They had all been wired 3phase and earth no neutral. The installer of said kit had done just this used the earth as the neutral.
Said machines have since had rectification but could have been bloody lethal!

 

[Lucien Nunes]

Anyone ever come across a neutral using the earth on purpose?

Yes. As mentioned above, it has sometimes been done when 230V electronics are added to an existing 3-phase 400V machinery supply that never had a neutral because it was only originally powering motors. Typically these would be on large TN-C-S or TN-S supplies with a reliable and substantial company earth.

I'm just wondering if there is a scenario, other than a break in the earth, where someone could get a shock through this setup?

No, this is the heart of the problem. One high-resistance connection and everything downstream of it becomes live.

On the other hand, it was standard practice in many places for a long time, to use the same wire as earth and neutral all the way to the load. That is TN-C, as opposed to TN-C-S where the earth and neutral separate at the origin. Poke around a German house that hasn't been rewired since the early 1960s and you will probably find sockets with a link between N & E, fed by a grey wire. Even where you find a later addition with a G/Y earth and a blue neutral, they might combine upstream*. TN-C was permitted in Finland until about 20 years ago IIRC, although they required a larger conductor for the CNE. The other thing about these European TN-C's was that rather than being sneaky unexpected bodges, they were designed-in; often recognisable by the wire colours, and fed from TN-C supplies. Electricians would be well aware of the hazards of a broken CNE and would take care to prevent it.

*This is what it looked like: A quick European wiring puzzle with a simple answer - https://www.electriciansforums.net/threads/a-quick-european-wiring-puzzle-with-a-simple-answer.198851/

If you go back to earlier UK regs it was actually permitted here as well, in the form of earthed concentric wiring. E.g. the bare metallic sheath of MI or Stannos was allowed to be used as neutral, subject to some specific rules.

Obviously the light bulb itself was stopping a short circuit which is why it had been used for considerable time without blowing the rewirable fuse

Just as it does when the current is returning via the neutral. A great added feature of the humble light bulb

 

[Risteard]

Regarding the light switch, if it's a TNCS earthing arrangement then it would work fine without bothering any fuses, but it would become a problem as soon as an RCD is fitted, very very dodgy though.

Also a breach of ESQCR.

 

[not a sparky honest lol]

Quick question, in Bulgaria the neutral us classes as an earth. I have two 240v sockets that don't appear to be eathed. Can I just connect a wire from the earth to the neutral

 

[not a sparky honest lol]

Also a breach of ESQCR.

The sockets are wired direct on a spur, not from a light switch as the bulgies usually do. All other sockets tested and eathed. But these two random ones are not. Any ideas or solutions would be appreciated.

 

[captaincaveman]

Quick question, in Bulgaria the neutral us classes as an earth. I have two 240v sockets that don't appear to be eathed. Can I just connect a wire from the earth to the neutral

No and why are they not earthed??? Presumably there's no CPC in the cable?