4Mm Radial Off Ring Cct

[SLIPSHOD & SLAPDASH]

Just because they dont mention a larger cable does not rule it out.

 

[SPECIAL LOCATION]

is this still going on?

I have to say that philbas has sort of said in three line what I said earlier....

Not sure I should add to this after a fair amount of Dr Bells medicine, but we need to ensure the cable is protected we have 32A protection, 4mm is good for that, a balanced ring can handle that, what we have to ask is have we unbalanced the ring to much, only the man/women on the spot can decide that.

My longer version...

as wrote on post #24...

YES.... Dependant upon certain design criteria...

and

NO... based on certain design criteria...

BUT........................

as we have been told very little fact about the proposed design...

its damn near impossible to give an accurate answer....

Possibility this is due to the subtle difference between learning regulations and installtion..

without understanding design...

few hints...

i) proposed max demand or load of the new bit you want to add onto the installtiuon...

ii) suitable cable big enough to carry this load...

iii) suitable protective device for this cable...

iv) any relevant correction factors that will alter the above values...

and then we go into....

what is the load on the existing circuit that you want to extend...

how physically big is the existing circuit?

what floor area does it cover?

how many other radials are there branching off it?

where about around the ring are you looking at extending from, halfway..quater..third..fifth??

how long is your new radial?

what are your existing Zs vales.. what is your calculated prospective Zs..

what will you amended R1+R2 be

what will the new volt drop be?

etc..

etc..

I can think of numerous arguments to make if both acceptable AND unaccepatble..

but..

I cannot write out all the feasibilities or I will be on here all afternoon!

:C

Now unless the Op has come back and told us more facts....

wot I haven't noticed ...

you can argue infinitum till your brains expode....

At the end of the day its down to the design based upon the clients specific requirements...

and the condition of the existing installtion..

It may be YES..

OR

it may be NO!!!!

but without a few more facts...

we ain't got nothing to discuss!!!

:coat

 

[SLIPSHOD & SLAPDASH]

And its as easy as that, good night.

 

[SPECIAL LOCATION]

Appendix 15 shows,..

Some common options...

BUT..

not ALL options!!

Possibly going back to FUNDAMENTAL PRINCIPALS chapter 13....

thats notwithstanding the last paragraph of reg 120.3

Departures from BS7671!!

 

[philbas]

ok lets go back to Basics, the regs are a guide to how you MAY comply with the law, they are not the law, it is up to the parson on the spot to do a competent job and comply with the law, that can only be decided in court, be sure you can stand behind your decision

 

[apprentice87]

Hi Philbas,

My point exactly...

If you do things EXACTLY to the book, then you have nothing to worry about...

Do you really want to be in a court, with a jury comprised of ordinary people, with a prosecuting barrister asking in his most "superior" tone;

"Mr electrician, in my hand i hold a copy of the IEE wiring regs. Now, i will ask you again, did, or did not, your installation comply with the regulations" It will not do you much good to reply "errrm no, splutter splutter, but they are only guidelines, you can come up with your own "home brewed" solutions if you want"

What inferences do you think the jury will draw from that???

The highway code is only guidelines, but ignore them and see what happens....

In the front of the regs book it clearly states; "The regulations are non-statutory. They may, however, be used in a court of law in evidence to claim compliance with a statutory requirement"

So yes, the regs ARE only guidance, and yes, it may VERY WELL be possible [and technically ok] to come up with perfectly satisfactory alternative ways of doing things, but i personally, would much rather be in the happy position of being able to have the defence barrister be able to state that;

"We have commissioned a report from a consultant in these matters, and he and the HSE are both in agreement that john's installation complies with the IEE "guidelines" 100%"

Now what inferences do you think the jury will infer from that....

john....

 

[steptoe]

do yuo ever check your self Steps. If exporting outside of building ie to shed I can see an argument for this, or possibly within an industrial unit. But even large domestic property, properly bonded etc etc, I would be 'surprised' to get a problem. 90m2 isn't that big an area

in the same way you will get VD on your LIVEs then you will also get it on your CPCs,

you need to allow for this.

90m2 isnt a massive area, but it was mentioned about over this,

and Ive worked in some domestic that are waay larger than commercial,

in fact just been in a 3 storey house tonight would have a footprint maybe a 3rd of a football pitch!!!

spent 2 hours trying to identify a faulty stat, there are 19 of them.!

Earth potential will NEVER be constant throughout an installation.

All than can be achieved is that the potential relative to adjacent metalwork is kept to acceptable limits.

well, exactly as I thought,

someone with a bit [lot] more intelligence than me has actually put it properly,

[or you could put a rod in every room O) ]

a very good example of earth potential never being the same is -

does anyone remember the horse that got electrocuted at the racecourse?

you need to ensure your faraday cage remains intact, and , yes, IMHO, it can change, remember, not many people do bonding anymore,

due to some people needing to keep their jobs and have some self importance about themselves.

 

[kme]

Hi Philbas,

My point exactly...

If you do things EXACTLY to the book, then you have nothing to worry about...

Do you really want to be in a court, with a jury comprised of ordinary people, with a prosecuting barrister asking in his most "superior" tone;

"Mr electrician, in my hand i hold a copy of the IEE wiring regs. Now, i will ask you again, did, or did not, your installation comply with the regulations" It will not do you much good to reply "errrm no, splutter splutter, but they are only guidelines, you can come up with your own "home brewed" solutions if you want"

What inferences do you think the jury will draw from that???

The highway code is only guidelines, but ignore them and see what happens....

In the front of the regs book it clearly states; "The regulations are non-statutory. They may, however, be used in a court of law in evidence to claim compliance with a statutory requirement"

So yes, the regs ARE only guidance, and yes, it may VERY WELL be possible [and technically ok] to come up with perfectly satisfactory alternative ways of doing things, but i personally, would much rather be in the happy position of being able to have the defence barrister be able to state that;

"We have commissioned a report from a consultant in these matters, and he and the HSE are both in agreement that john's installation complies with the IEE "guidelines" 100%"

Now what inferences do you think the jury will infer from that....

john....

John.

As a general rule, we have discussions (electrically) over TWO things in here, I think.

1. Interpretation of a particular reg. , and whether a certain practice is excluded or not.

2. The correctness and feasibility of procedures which are NOT included in the book, but which may still comply.

As was said above - just because it isn`t there, doesn`t mean it isn`t right. The book isn`t meant to be an exhaustive pictorial guide on what can and cannot be done, I tend to think of it more as a "check valve" on inspiration - providing the facts required for ME to decide if the approach I want to take is compliant.

Further - as regards "defence in court". Don`t forget, this was the year when a judge decided to completely ignore 7671, as it has no standing in law. So that defence may or may not work. Blindly following a step-by-step "how to" is no substitute for a working knowledge, which is a defence I`d be MUCH happier with, than just being able to say:

"He has this particular book (even though it isn`t legal), AND he can read - so he MUST be ok then........

I`m not having a go. I`m just saying that, because lollipop circuits, or 16A mcb submains on rings aren`t shown, doesn`t make them non compliant. Site-specific influences will be the deciding factors, in every case.

KME

 

[SLIPSHOD & SLAPDASH]

ok lets go back to Basics, the regs are a guide to how you MAY comply with the law, they are not the law, it is up to the parson on the spot to do a competent job and comply with the law, that can only be decided in court, be sure you can stand behind your decision

Lets not bring religion into it

 

[paul b b]

I had an unbalanced ring last week, though that's another story!!

 

[SLIPSHOD & SLAPDASH]

I had an unbalanced ring last week, though that's another story!!

Thats my line :innocent

 

[binky]

I never mentioned 4mm radials, cannot see the relevance to the original post...

but this is exactly what we are dicussing '87 4mm radial spurred of 2.5mm ring

 

[Chr!s]

in the same way you will get VD on your LIVEs then you will also get it on your CPCs,

you need to allow for this.

90m2 isnt a massive area, but it was mentioned about over this,

and Ive worked in some domestic that are waay larger than commercial,

in fact just been in a 3 storey house tonight would have a footprint maybe a 3rd of a football pitch!!!

spent 2 hours trying to identify a faulty stat, there are 19 of them.!

well, exactly as I thought,

someone with a bit [lot] more intelligence than me has actually put it properly,

[or you could put a rod in every room O) ]

a very good example of earth potential never being the same is -

does anyone remember the horse that got electrocuted at the racecourse?

you need to ensure your faraday cage remains intact, and , yes, IMHO, it can change, remember, not many people do bonding anymore,

due to some people needing to keep their jobs and have some self importance about themselves.

LMFAO.

What a load of rubbish!!

If your point is designing to limit touch voltage your miles off.

 

[binky]

so what's your answer to the question then Chr!s?

 

[Chr!s]

so what's your answer to the question then Chr!s?

Sorry Binky, which Question?

 

[steptoe]

LMFAO.

What a load of rubbish!!

If your point is designing to limit touch voltage your miles off.

and when did touch voltage get mentioned anywhere but your post,?

I think you need to google a bit more.

 

[binky]

Sorry Binky, which Question?

try the original post, but as you seem to be nothing more than a wind up merchant, I somehow suspect nothing constructive is ever likely to come from you?

The whole point of the original construction of this forum was to avoid the negative over argumentative shite of other forums. I don't think you have quite got the hang of that yet?

 

[Chr!s]

and when did touch voltage get mentioned anywhere but your post,?

I think you need to google a bit more.

Okay, I apologise.

Though, you mention PD, Horse electrocuted, Faraday Cage, Bonding, hence why it's seems you are referring to touch voltage.

I'm all ears Steptoe, I'm interested in what it is your designing to?

 

[Chr!s]

try the original post, but as you seem to be nothing more than a wind up merchant, I somehow suspect nothing constructive is ever likely to come from you?

The whole point of the original construction of this forum was to avoid the negative over argumentative shite of other forums. I don't think you have quite got the hang of that yet?

Okay

1, BS7671 only provides several regs regarding Ring Circuits, it doesn't provide the design.

2, The onsite Guide contains a design for a ring circuit, certain parameters need to-be met.

3, In what the op is describing, it differs from the IET design, so you need to be competent to design such an arrangement.

4, Appendix 15 is informative, and states various other chapters of BS7671 that need to be met.

5, Is it possible, well there's no direct reg with respect to a spur, so providing you meet 433.1.103 which allows a reduced csa and the spur does not effect that and meets all other requirements of BS7671, then why is it not?

6, Is the op competancy, I'd say not, it's not rocket science, it's not that easy either.

7, Can you put a CU on Ring, well you won't be using 433.1.103.

 

[professional]

People need to be aware that if work is carried out that is not covered by the basic designs included in the OSG they need relevant DESIGN KNOWLEDGE.

What`s the problem? - surely all of you 5DW`s out there have the required design knowledge, if you did the extra 1/2 day, that is .....