Myths

[EFLImpudence]

As people seem to be in the mood for long discussions about any little thing, I wondered how and why some things become part of folk lore even though they are completely meaningless and unnecessary.
Could it be from such bodies as the recently mentioned safety charity and best practice guides whose authors presumably have to justify their existence?

A poster in a thread this morning with regard to earthing a back box mentioned the fixed lug 'rule'; i.e. if one of the lugs is part of the back box then earthing the faceplate is sufficient.


As the back box is not an exposed-conductive-part therefore does not require earthing at all, I wondered who it is that considers it their job to make up rules for implementing things which are not required nor necessary.

Perhaps the same happened regarding isolators and fuses for extractor fans (in the U.K.).

 

[ebee]

As the back box is not an exposed-conductive-part therefore does not require earthing at all,

Hmm well OK but often the surounding plaster and sometimes the wall can be very damp or even a bit wet in older homes.
Where I live there are a lot of early 1900s terraced houses, leaky roof/rising damp etc etc.
This can make the area around the back bow a bit conductive.
I would rather the back box was effectively earthed.
The fixed lug might help achieve this if the screw is tight-ish but often are slack, forgot to re-tighten after decorating etc etc and sometimes the screws are a bit corroided anyway so not the best way to ensure soundly earthed.
I always use an earthwire to the earth terminal on such boxes whether a seperate tail or a longer cpc doubled.
I think it is better practice.
In fact, I have said before, I once saw a place where many socket/switchplate screws had been replaced with nylon screws for some reason.

 

[ericmark]

When I did my apprenticeship we never had access to regulations, they were kept in office and we were never allowed to browse.

We were told so many half truths. The main problem is English. Take the earth to light fittings, I knew the rules changed in 1966, but the wording has changed.

Also meaning of words, a filament lamp in 1966 would not have referred to an LED filament.

 

[flameport]

Could it be from such bodies as the recently mentioned safety charity and best practice guides whose authors presumably have to justify their existence?

That's exactly where most of it came from.
The rest was from books that people wrote.
Those who wrote the books and worked for the organisations were in many cases the same people.

Then repeat over decades by those who accept such 'advice' as the truth, and it becomes 'the regs' even though it isn't and never was.

Other examples include 'ring mains' which were never called that, and light switches in bathrooms must be pull cords (this was never true).

 

[plugwash]

A poster in a thread this morning with regard to earthing a back box mentioned the fixed lug 'rule'; i.e. if one of the lugs is part of the back box then earthing the faceplate is sufficient.

That one is published in an IET guidance note.

 

[FrodoOne]

Also meaning of words, a filament lamp in 1966 would not have referred to an LED filament.

Why did you introduce that statement?

In 1966 it would have been most unlikely that
LEDs would have been "foreseen"
and
that the unforeseen LEDs could be made into "strings" to resemble an Incandescent Filament.

See https://en.wikipedia.org/wiki/LED_filament
"A LED filament type design light bulb was produced by Ushio Lighting in 2008, intended to mimic the appearance of a standard light bulb. Contemporary bulbs typically used a single large LED or matrix of LEDs attached to one large heatsink.
As a consequence, these bulbs typically produced a beam only 180 degrees wide. By about 2015, LED filament bulbs had been introduced by several manufacturers. These designs used several LED filament light emitters, similar in appearance when lit to the filament of a clear, standard incandescent bulb, and very similar in detail to the multiple filaments of the early Edison incandescent bulbs.

 

[ericmark]

Why did you introduce that statement?

In 1966 it would have been most unlikely that
LEDs would have been "foreseen"
and
that the unforeseen LEDs could be made into "strings" to resemble an Incandescent Filament.

See https://en.wikipedia.org/wiki/LED_filament
"A LED filament type design light bulb was produced by Ushio Lighting in 2008, intended to mimic the appearance of a standard light bulb. Contemporary bulbs typically used a single large LED or matrix of LEDs attached to one large heatsink.
As a consequence, these bulbs typically produced a beam only 180 degrees wide. By about 2015, LED filament bulbs had been introduced by several manufacturers. These designs used several LED filament light emitters, similar in appearance when lit to the filament of a clear, standard incandescent bulb, and very similar in detail to the multiple filaments of the early Edison incandescent bulbs.

The allowing of lighting without an earth wire pre-1966 was only for filament lamps, which is why I talked about filament lamps, when the rules changed if ever for discharge lamps I don't know? So it is unlikely we have ever been allowed pendent lamps using CFL or standard LED lamps since the war.

 

[Murdochcat]

Napit codebreakers book is to be trusted

 

[EFLImpudence]

It should not be necessary.

 

[ericmark]

Napit codebreakers book is to be trusted

Is it? Same as the best practice guide, it is what some one thinks should be done.

The big question is should one use two forms when checking the electrics, or try to combine into one?

When I did inspection and testing in collage I did three courses, one on regulations, one for installation, and one for equipment. I have not really understood why lighting is the odd one out, and is included with the installation rather than current using equipment, maybe as traditionally the current using equipment was just the bulb, and can't really see how you PAT test a bulb.

But I have seen so often where items which should go one the inspection and testing of in service equipment has been entered on the EICR in error.

 

[Murdochcat]

Napit codebreakers book is to be trusted

This is definitely a myth

 

[Murdochcat]

It should not be necessary.

Quite correct. But too many wannabe sparks use it as gospel

 

[BlueLoo]

As people seem to be in the mood for long discussions about any little thing, I wondered how and why some things become part of folk lore even though they are completely meaningless and unnecessary.
Could it be from such bodies as the recently mentioned safety charity and best practice guides whose authors presumably have to justify their existence?

A poster in a thread this morning with regard to earthing a back box mentioned the fixed lug 'rule'; i.e. if one of the lugs is part of the back box then earthing the faceplate is sufficient.


As the back box is not an exposed-conductive-part therefore does not require earthing at all, I wondered who it is that considers it their job to make up rules for implementing things which are not required nor necessary.

Perhaps the same happened regarding isolators and fuses for extractor fans (in the U.K.).

Rules are only needed where knowledge and application are missing.
These days, people think less and rely on others more so rules have to fill in the void.

 

[Murdochcat]

Rules are only needed where knowledge and application are missing.
These days, people think less and rely on others more so rules have to fill in the void.

I think the PowerPoint generation and schooling are to blame.

People get too used to bullet point teaching rather than reading the full regs

 

[CBW]

People get too used to bullet point teaching rather than reading the full regs

I could read a book cover to cover (when I can be arsed) but not remember a damn thing. Teaching methods had to address for the likes of me, unfortunately.