Did we ever arrive at an answer on this one ?

I remember we had a thread on neutrals burning out  on stuff like shower switches , Immersion heaters & sometimes storage heaters.

Did we decide there was a particular reason for it to always be the neutral ?      If so what was it ?  

Reason for asking ,  our erstwhile apprentice came over with a picture of a  control module from a DIY solar panel fitted to a narrow boat .    He wondered if the fault was caused by the  engine vibrations  loosening terminals , fair enough  assumption .      

I suggested it was a basic loose DIY connection but again it was the neutral  .  Melted plastic , heat damaged box terminal , melted insulation on cable etc. 

Speaking for myself  I've  replaced  a load of shower pull switches which all seemed to have burned out neutrals.   

Funnily enough I looked at a faulty shower switch this week and it was the incoming live which had melted the terminal ....

Deke, is the owner of the boat building the entire system from scratch, or a kit of parts? I only ask as if He is building from scratch, He could be contravening the Recreational Craft Directive, which if isnt followed to the tee, could render His boat as not being passed as safe for use on the canal system.

Andy  Guinness  

Come across loose connections on the phase conductor also.

Zeespark said:

Deke, is the owner of the boat building the entire system from scratch, or a kit of parts? I only ask as if He is building from scratch, He could be contravening the Recreational Craft Directive, which if isnt followed to the tee, could render His boat as not being passed as safe for use on the canal system.

Andy  Guinness  

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The guy is a Mr DIY  apparently , sent for the kit I believe .    I doubt he cares about contravening  any directives  TBH  .  

I think the answer is people don't regard neutral as being as important as line, so it doesn't get done up quite as tightly - that's my theory! 

binky said:

I think the answer is people don't regard neutral as being as important as line, so it doesn't get done up quite as tightly - that's my theory! 

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I would like there to be an actual scientific reason behind it, however I don't know one. Still, lots of people know far more than me, so hopefully I'll find out one day. 

However my opinion is one of, maybe people just remember it more, as conversations like these lodge it in peoples brains. An they just forget the burnt up line conductors. Or partially as you say, they get less attention. 

Also we test R1+R2 not R1+RN for most circuits, so lose conductors in the line or CPC are immediately picked up.

It could well be one of those things from the  Trade Mythology section . 

I'll list a few to remind us :-  

1)  You must not use tallow or lube to draw cables into conduit .    (  Correct but only applied in the days of VIR  where it affected the braid & rubber. ) 

2)  Its always the neutral that burns out .       (  Jury is out on this one )

3)  You can't pass a neutral through a switchbox  or use a connector in a sw/box.    (  Total nonsense  , been hearing it for years . )  

4)   Metal capping /sheathing must be earthed  .     ( Only ever seen it on B,ham City Specifications )  

5)   You can't pass  the uncut leg of a ring through a socket box.   ( Another  great myth I 've come upon a few times ) 

Evans Electric said:

Metal capping /sheathing must be earthed  .     ( Only ever seen it on B,ham City Specifications )  

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That is also a Jock thing.....and a continuity bond with two crimps across each join in it

Now you ARE kidding me !!!!

On saying that , we were once asked to bond , in the same manner as your sheathing .........that flimsy silver aluminium foil that encases insulation on large pipework , as in boiler rooms.      By a private consultant ...a crimp lug ..4mm G/Y ...& push a self tapper into the foil. :C  

Evans Electric said:

Now you ARE kidding me !!!!

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Nope 

I was there

Glasgow Council,clerk of works

I told him he was an ill informed ill educated

I would have expected no less my learned friend .  These  ideas are taken in by people in the trade, perhaps from other sparks ,  and they become real .   

A spark I worked with had one about running threads  on conduit  .    We were at the start of a new  build school  , made up some conduit  with giant double sets in it  so put a runner on the end ........the guy comes out with  .. " You can't do another runner now on this job "           Its a 6 month job  and  you can't have another runner on it ...wheres he get this from ?    

There used to be a thing , perhaps a hospital spec  that stated that ONE section of a conduit run should use  only one runner ..... but he had it in his head  it was one per job .     Like  the Runner Police   will go round checking    .( Perhaps its where the Bow Street Runners came from ) 

My mate , because of the firm he worked for for many years ,  maintained you couldn't fit a pendant in a kitchen  ( new housing )  must be a batten holder . 

Firm I started with used inspection elbows , bends & tees .  I  moved on halfway through  apprenticeship  and never saw the things  again  .    

It was in the M&Q regs that no more than one running coupler could be used in a run of conduit. If the conduit was being used as the circuits CPC. 

Something to do with those sections were more likely to degrade quickly due to the adverse environment and having either the galv protection or paint removed with the threading process. This rule was removed in the later M&Q ACOP. However a lot of places kept it in their site specification. 

Rob. said:

no more than one running coupler could be used in a run of conduit. If the conduit was being used as the circuits CPC. 

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Good point , it was always the earth path then .   The guy thought it meant for the whole place .    Bit like , you can only do one runner in your lifetime  . 

so in the days of steel conduit and singles with no cpc  what happened then? 

binky said:

so in the days of steel conduit and singles with no cpc  what happened then? 

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There was never any mention in the regs for this, at least since the 16th, an I'm fairly certain the 15th edition either. 

Like I mentioned, it was either other specifications that mentioned it, or just site standards. 

Rob. said:

It was in the M&Q regs that no more than one running coupler could be used in a run of conduit. If the conduit was being used as the circuits CPC. 

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Ye gods, only one running coupling in a conduit run? I do remember that stipulation RoB.

I took on renovating a switchroom in my spare time at work. All the 550V dependant manual Reyrolle HH gear had to go, replaced with two new GE MiniForm panels, one for 550V and a new panel for 433V.

All the original conduit was imperial and I only had metric conduit, adapters and running couplings were the order of the day. When stores sent me galvanised instead of black japanned conduit I just about blew a gasket. Quite a few spray cans of black enamel later things matched, it also meant that all running couplings were protected against rust. All modified runs were tested with a Ductor.

The switchroom renovation took a mate and I the best part of two years.

Tony S said:

Ye gods, only one running coupling in a conduit run? I do remember that stipulation RoB.

I took on renovating a switchroom in my spare time at work. All the 550V dependant manual Reyrolle HH gear had to go, replaced with two new GE MiniForm panels, one for 550V and a new panel for 433V.

All the original conduit was imperial and I only had metric conduit, adapters and running couplings were the order of the day. When stores sent me galvanised instead of black japanned conduit I just about blew a gasket. Quite a few spray cans of black enamel later things matched, it also meant that all running couplings were protected against rust. All modified runs were tested with a Ductor.

The switchroom renovation took a mate and I the best part of two years.

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 I re did the works site canteen/kitchen/mess in stainless conduit, had more than one running coupling there too! Still, not likely to corrode, even normal steel wouldv'e been protected by all the oil an grease the "cooks" used.

I know why it was stipulated, you know how long even well designed galv systems fared under some of the conditions on site. Less than a few years, an even spraying a coupling with galv spray it's still the weak point, spray is no where near as protective as hot dipping. 

binky said:

so in the days of steel conduit and singles with no cpc  what happened then? 

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What happened about the earthing ?      

The steel conduit was the earth ,  hence you find conduit installed by older sparkies is done up good & tight  ,  especially brass bushes .  ( Which were twice as thick as what you get today )  .

One  of the reasons that,   on a flush KO box ...   you get one fixed lug & one adjustable ,   the earth terminal  of a socket has that strap that  connects to the fixing  screw,  then the box lug .  At one time  when the socket was removed from the wall there would be no earth on the plate .   So an earth terminal was introduced on the back of the box  and  jumper wire  added. 

And consequently a green earth wire added with the red / blacks   .

Another thing  old sparkies do , including  me,  was  to  bump SWA locknuts  up tight with a  hammer / chisel  as the locknuts became thinner & thinner  and the grips kept shearing off them .    The armouring was always the earth  by the way . 

Evans Electric said:

 especially brass bushes .  ( Which were twice as thick as what you get today )  .

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Got my old Bush King out the other day......perfect solution to a tricky install situation.

put it away 2 second later. Bush flats were too fecking  small to fit. Just to satisfy my curiosity I found an old flange coupling and Bush complete with lead washer ( not see one for decades and I bet most newbies don't even know what one is!)

Fitted perfectly....more brass than a payday night out

surely these are made to a standard?....or has that gone by the wayside!

BE conduit W.T.A.F. IS that all about now!....it's not even paint on it, more like nail varnish!