Neutral in the earth bar

Knobhead · Mar 30, 2012

I'm going getting my tin hat before E54 gets here!

View attachment 11508

SPARTYKUS · Mar 30, 2012

One point- i assume you mean neutral in CU...? Can't use this as its disconnected when you switch off unlike the TNCS main earthing conductor, you know Dave, the one they fit because the laws of physics suddenly changed (about same time as TNS started looking expensive).

Disagree re Tt best. TNS. I like the solid line back to the transformer....

Engineer54 · Mar 30, 2012

Geordie Spark said:
I've mentioned this before on other thread here, but I'll repeat it here:

When I was at college learning all about the 16th Edition, the lecturer told u that in his view it was acceptble to do this in the case of (say) a halogen security light where no earth / CPC was available.

He also said that - in his view - the TT system of earthing was better than TNS & TNCS because with TT YOU were in control of the earth rod, while with the other two you are relying on other folk to maintain it - or not.

If and only if, you can get your Ra down to TN levels. Really what's the point in being in control of a 200 ohm or thereabouts Ra??

Yet another lecturer that is probably anti PME that comes out with daft statements to his students!! Who in there right mind would choose a TT system earth over a TN-S earth, ....especially in the UK!! lol!!!

As for using the neutral as an earth on a security light, ....Acceptable, not in my world!!! If the cable doesn't carry a CPC, then bloody well install one that does, or don't install the light in the first place!! Where do these lecturers come from these days!!!!

SPARTYKUS · Mar 30, 2012

Engineer54 said:
If and only if, you can get your Ra down to TN levels. Really what's the point in being in control of a 200 ohm or thereabouts Ra??

Yet another lecturer that is probably anti PME that comes out with daft statements to his students!! Who in there right mind would choose a TT system earth over a TN-S earth, ....especially in the UK!! lol!!!

As for using the neutral as an earth on a security light, ....Acceptable, not in my world!!! If the cable doesn't carry a CPC, then bloody well install one that does, or don't install the light in the first place!! Where do these lecturers come from these days!!!!

LOVE IT.

Had a bit of experience with this "lecturer" syndrome recently (and lets not tar all with the same brush of course, like Electrical Trainee)

shower not working at a rented house for a company I do / have done loads for, weird fault as seemed shower was kaputt.

To cut a long story short, it was an intermittent fault - the plumber replaced the shower with a new one that also seemed knackered - called back and dis assembled every nut and bolt and cable from shower to (separate) mini CU in meter cupboard - as managedto catch fault during a fault situ - showing 32 Volts instead of 245 (sorry I mean 230 silly me).

turns out the nuggett had screwed the main RCD neutral connection onto the insulation of the solid neutral bar feeding it....hence the lack of excitement in the shower department. Further more he'd used a bit of 16mm T+E to feed this mini CU from the henley. Loads of brown and blue on show (oh naughty! just one single layer of insulation!).

The owner was very down trodden, he was an old friend who she told me "but he's a lecturer"

SPARTYKUS · Mar 30, 2012

SPARTYKUS said:
One point- i assume you mean neutral in CU...? Can't use this as its disconnected when you switch off unlike the TNCS main earthing conductor, you know Dave, the one they fit because the laws of physics suddenly changed (about same time as TNS started looking expensive).

Disagree re Tt best. TNS. I like the solid line back to the transformer....

E54

Thanks for saying "likes this":sunny:

Geordie Spark · Mar 30, 2012

Engineer54 said:
If and only if, you can get your Ra down to TN levels. Really what's the point in being in control of a 200 ohm or thereabouts Ra??

Yet another lecturer that is probably anti PME that comes out with daft statements to his students!! Who in there right mind would choose a TT system earth over a TN-S earth, ....especially in the UK!! lol!!!

As for using the neutral as an earth on a security light, ....Acceptable, not in my world!!! If the cable doesn't carry a CPC, then bloody well install one that does, or don't install the light in the first place!! Where do these lecturers come from these days!!!!

I agree with all you've said !!

It was interesting to note that when I did my 17th Edition at the same college, this bloke was no longer there ....

drew35 · Mar 30, 2012

It would trip the RCD if someone touched it and had connection to ground though wouldn't it?

i=p/u · Mar 30, 2012

that's why equipotential bonding conductors are bigger on a tn-c-s system..

SirKit Breaker · Mar 30, 2012

The light Class 2 fitting you are removing, is double insulated, and so basic and fault protection is provided by its construction, and no connection is required to earth of the fixed installation. No earth No problem.

You intend to fit a Class 1 fitting to the existing wiring. Class 1 fittings rely on an earth connection to the fixed installation for fault protection, you cannot get a connection to the fixed installation for fault protection if there isnt one there. If either Live or Neutral become disconnected the fitting could go live, and you would never know until you touched it. There is no earth fault loop to trip the breaker. No earth Big problem.

Cheers...........Howard

Geoffsd · Apr 1, 2012

Hasn't everyone missed the point of the original question?

If the neutral were connected to the earth bar at the CU the circuit would still not have a CPC and so, notwithstanding all the above arguments, would make no difference to the class 1 fitting.

Knobhead · Apr 1, 2012

Geoffsd said:
Hasn't everyone missed the point of the original question?

If the neutral were connected to the earth bar at the CU the circuit would still not have a CPC and so, notwithstanding all the above arguments, would make no difference to the class 1 fitting.

Now you read the original OP.

The theory and physics are perfectly sound. In fact in some countries it is used as normal practice.

Geoffsd · Apr 1, 2012

Tony said:
Now you read the original OP.

I see what you mean.

But when read in connection with the thread heading I didn't think making a connection between N & E at the fitting was
meant?

Knobhead · Apr 2, 2012

True, it is confusing.

There was a thread a while ago from a British guy in Bulgaria of some were like that (Outer Mongolia). Where using neutral as the earth was the “norm”. As I recall all properties were PME’d with a local spike. Then everything was wired in twin with no earth, the chassis of the appliance was connected neutral. For some reason no one was impressed, can’t understand why?:smilielol5: E54 may be able to remember what country it was he had quite a bit to say on the subject.

Engineer54 · Apr 2, 2012

Tony said:
True, it is confusing.

There was a thread a while ago from a British guy in Bulgaria of some were like that (Outer Mongolia). Where using neutral as the earth was the “norm”. As I recall all properties were PME’d with a local spike. Then everything was wired in twin with no earth, the chassis of the appliance was connected neutral. For some reason no one was impressed, can’t understand why?:smilielol5: E54 may be able to remember what country it was he had quite a bit to say on the subject.

Think it was either Bulgaria or Romania, an Eastern European country anyway!! lol!! As far as i remember he was talking about linking the neutral to earth at every socket outlet!!! lol!! I don't think the locals were even using earth rods/electrodes on there installations, they where just using the neutral, which is not PME at all, that's just using the neutral as as a combined earth and neutral conductor around the installation. ....Rather them/him than me!! lol!!