Sparkingchip:


However in 1882 I’m sure “Shall” would have been considered as a definite requirement.

Perhaps someone might have a look in a First Edition and see how often it is used?

Not once.


'Should' is used quite a lot - except in one Regulation which contains 'it is essential that'



Today, we use the BSI "Rules for structure and drafting of UK standards" - which broadly follow ISO/IEC Guide 2:2004. Using these rules, Normative provisions ("requirements") use"shall", and Recommendations use "should", and instructions use the imperative mood.


Importantly, though, the advised (informative) approach to coding relates not necessarily to conformity to BS 7671, but more the assessment of the safety of the installation, or part of it.


A good example would be a damaged fixed appliance or consumer unit, where live conductors are exposed ... only the selection and perhaps connection of these is covered by BS 7671 (the basic protection being part of the product or assembly standard) but the fact remains that part of the installation is unsafe.


Would you omit to code that because you can't find a "shall" requirement in BS 7671 (being very picky, the "shall" requirement for the basic protection of the product or assembly being outside BS 7671 per Regulation 113.1)?


By the same token, just because there is a "shall" requirement in BS 7671 doesn't mean you should apply a C1 or C2 just because there's a "shall" requirement.


Have a look at Page 476 of the 18th Ed (blue book) - you will see that even the guidance in BS 7671 itself says you can C3 a "shall" requirement - that of RCDs not present in older installations! (Item 2 under "Guidance for the Inspector")

Chris Pearson:

Simon Barker:

Sparkingchip:

Shall is, however, still widely used in bureaucratic documents, especially documents written by lawyers. Owing to heavy misuse, its meaning can be ambiguous and the United States government's Plain Language group advises writers not to use the word at all.

Wikipedia- Shall and will.

Whenever I have read or written requirements documents, "shall" has meant the same as "must" - it's a hard requirement.


"Will" is a statement of intent, and not a requirement.

Interestingly, ESQCR 2002 has over a hundred instances of "shall". Some could be substituted with "will" e.g.

1.—(1) These Regulations may be cited as the Electricity Safety, Quality and Continuity Regulations 2002 and shall come into force on 31st January 2003.


Others could be substituted with "must" e.g.

(4) A consumer shall not combine the neutral and protective functions in a single conductor in his consumer’s installation.

I am sure they used the word "shall" in "These Regulations may be cited as the Electricity Safety, Quality and Continuity Regulations 2002 and shall come into force on 31st January 2003." deliberately.  It's not a statement of intent - that's the date on which it definitely is going to happen.