17 th edition amendments

[Evans Electric]

I read that ammendments to the 17th are in the pipeline , forgot the date though. What the hell else can they come up with , surely this is not yet another money making scam by holding something back to generate another flood of payments.

Funny how , after the various let downs by the establishment during the last year, it becomes difficult to trust anyone these days.

 

[Jono Pashley]

So will it be a reprint of BRB with the additions or another sheet of paper to stick in the back...i see a excuse to boost BRB prices back up coming.

 

[green-hornet]

To be fair they did talk about a delay in publishing the 17th because of some insertions.

The Doctor has shown one such fault in the regulations on this very forum.

Teething troubles and the usual un-real world in which some office suits work in, mean there is always going to be some ammendmants.

One ammendment may be an inclusion into the book some cables that meet the requirements of not requiring rcd protection yet have to be put on a certificate as a deviation under the current regulations.

Yime will tell all as they say.

 

[the doctor]

The Doctor has shown one such fault in the regulations on this very forum.

Another one perhaps?

page 50 BS 7671

Table 41.5....

"Maximum earth fault loop impedance (Zs) to ensure RCD operation in acc.......for final circuits not exceeding 32A"

So then,

1 are distribution circuits not covered then?

2 what has the 32A maximum got to do with it

i reckon they have confused this table with table 41.1 on page 46 which deals with disconnection times for "up to 32A"

would you like more?

 

[a1]

Another one perhaps?page 50 BS 7671

Table 41.5....

"Maximum earth fault loop impedance (Zs) to ensure RCD operation in acc.......for final circuits not exceeding 32A"

So then,

1 are distribution circuits not covered then?

2 what has the 32A maximum got to do with it

i reckon they have confused this table with table 41.1 on page 46 which deals with disconnection times for "up to 32A"

would you like more?

Yes Please TD.

 

[green-hornet]

Ya got to love the doctor for finding them.

I see another book on the horizon

 

[a1]

Ya got to love the doctor for finding them.

Indeed

I see another book on the horizon

Yeah, "The real 17th Edition". By The Doctor.

 

[the doctor]

ok then.....

table 41.1 and the following two regulations list the disconnection times as

up to 32A 0.4 TN and 0.2 TT

over 32 A and distribution circuits 5s TN and 1 s TT

however, when you turn over a page you find the maximum Zs tables

41.2 0.4s for fuses

41.3 0.4 and 5s for breakers

41.4 5s for fuses

no mention of 0.2 or 1s disconnection, obviously another copy and paste from the old bookApplaud Smiley

more?

 

[a1]

more?

Yes Mate. keep Going.

 

[Nicky Tesla]

ok then.....table 41.1 and the following two regulations list the disconnection times as

up to 32A 0.4 TN and 0.2 TT

over 32 A and distribution circuits 5s TN and 1 s TT

however, when you turn over a page you find the maximum Zs tables

41.2 0.4s for fuses

41.3 0.4 and 5s for breakers

41.4 5s for fuses

no mention of 0.2 or 1s disconnection, obviously another copy and paste from the old bookApplaud Smiley

more?

you're supposed to use the graphs for this not the tables

 

[the doctor]

ok then.....

section 411.8 ( reduced low voltage) 110/55v tells us in the text that disconnection times are 5s on everything. this is repeated in the title of table 41.8 on the next page.......

however if you go back to table 41.1 on page 46, this table tells me that any circuit up to 32 A if not a distribution circuit must have a disconnection time of

TN 0.8s

TT 0.3s

this is shown in the first column 50V <Uo<120V ( your Uo of 55 fits here)

so then, what really is the disconnection time for a 110/55 jobbie?

table 41.5 is a new european table and 41.6 is an antiquated uk one- they should be making their minds up rather than plotting with another rip off ammendmentROTFWL

more?

 

[the doctor]

you're supposed to use the graphs for this not the tables

so then, if i should use the graphs why not scrap all the tables? :coat

 

[the doctor]

ok,

i always teach a 17th by teaching people to navigate by using the contents page on page 3 and the contents page on each chapter.

if you go to a typical chapter contents page like chapter 52 on page 96 you will see the sections are always in bold. this is most helpful

however if you go to chapter 44 on page 78 you will see it is confusing as

441 and 442 should be in bold , but they are not. this is confusing for my students

more?

 

[the doctor]

Ya got to love the doctor for finding them.I see another book on the horizon

funny you should say that green hornet......

sat in my HQ on "The 2391 doctor"Guiness Drink

 

[a1]

Yes Doc. Keep going until I tell you to stop.

:^O

 

[the doctor]

Yes Doc. Keep going until I tell you to stop. :^O

mmmm

if the scope of BS 7671 tells me that the book is only concerned with ELV and LV ie up to 1000V ac and 1500V dc why is there section 442 ( faults in the LV system due to faults in the HV system)?

dont see it is my problem to be frank, and we have enough to worry bout as it isApplaud Smiley

in definitions, i do not understand how a spur can be a branch from a ring or radial? they have backed this up in appendix 15:O

will think of more....

 

[the doctor]

in definitions....

they list four persons..

competent

skilled

instructed

ordinary

go read them and report back............

ok, i dont understand the difference between skilled and competent. sounds like the same bloke to me:coat

also the instructed person can only be instructed by a skilled person-not a competent one;\

and lastly the ordinary person "is neither skilled or instructed"- does that mean he could be competent! ROTFWL

the iee makes me ill:_|

 

[the doctor]

another,

708 is caravan parks and 721 is caravans. now you need to plug in the caravan to the pitch so the flex sort of falls into both camps:|

708 states the maximum length of flex as 25m (page 192)

721 states the maximum length of flex as 25 + or - 2m (page 213)

so i make that 23-27 metres then:^O

 

[green-hornet]

another,708 is caravan parks and 721 is caravans. now you need to plug in the caravan to the pitch so the flex sort of falls into both camps:|

708 states the maximum length of flex as 25m (page 192)

721 states the maximum length of flex as 25 + or - 2m (page 213)

so i make that 23-27 metres then:^O

If that came up in an exam it could be the difference between a pass or a fail.

Shocking how they could get contradictions on something that was supposed to have been deliberated before release.

I will be asking for a free copy of any ammendments as the fault is not my own but theirs.

 

[the doctor]

yes green hornet, truly shocking.

that is why "committees" never achieve anything, it can only be done by one person stating it, right or wrong

your government is a case in point......Applaud Smiley