Anyone seen this before

[morqthana]

And I could say the same to you about understanding.

Right from the very start the ONLY point I have made, and made with utter consistency, is that none of the objections matter wrt the existence of the regulations about needing DNO agreement, and that none of the objections matter wrt having to have that agreement in order to comply with the regulations.

 

[JohnW2]

And I could say the same to you about understanding. .... Right from the very start the ONLY point I have made, and made with utter consistency, is that none of the objections matter wrt the existence of the regulations about needing DNO agreement, and that none of the objections matter wrt having to have that agreement in order to comply with the regulations.

And, in turn, I have agreed with all those points.

However, I have also made the different/additional point that I believe there are good and important reasons (which "matter") why DNOs should not be creating regulations which make no sense in terms of the indisputable fundamental scientific principles which underlie everything which happens in their industry - behaviour which is bound to result in some people questioning whether one can 'take seriously' anything they say or do.

 

[ebee]

A bit like the conspiracy theorists really.
People tend to take no notice of them because of some of the insane theories they come up with by by misinformation or exaggeration to such an extent that when they might actually mention something which does ring true in full or in part we might might have a tendency to disregard it anyway because of who said it.

Laws are laws and rules are rules that must/should be obeyed whether we like them or not whether we think them sensible ( to every extent) or not.

A one rule fits all makes things easier for all concerned even when we realise it does not always follow logic in each and every variation and extremes.

The use of generalisations can be helpful even if not strictly correct every single time.
It makes life easier. But sometimes a bit perverse

 

[martygturner]

My two pennies worth is that the industry needs to make up "regulations" or advice as its known due to the intellectual calibre of those its intended to guide.

Sparkies have a book to read and digest, the big brown one, but then that's a bit complex as its already dumbed down physics to make it accessible, when you dumb something down and don't use first principles you always end up with a fudge.

Hint we gave up making laws after Einstein said that we lived in a relative universe. When you apply a fundamental principle, say resistance, you need to do the calculation from scratch based on the circumstances you are observing. But that's a wee bit complex for a person who has not been exposed to the theory of science... that's not really covered until your second year of a science degree, managing variables and outliers( diversions from an implied norm) accounting for influences beyond the measured ( that's a Z variable) etc etc. So the big brown book lies and says it has done this for you... when it cannot as it cannot possible account for all the variations and drifts to a position of "in most cases"... hence the must is should.

If that's not enough, then its dumbed again to the On site guide, which now becomes a rule of thumb.... which is good enough in 90% of cases

Eg whats the boiling point of water on my stove ...

sparkie answer 100 degrees C

A level physics answer : That would depend on the location of the stove used to boil water and the type of water being boiled. In general we say that water boils @ 100 degrees C @ mean sea level however it can boil at range of temperatures depending on the atmospheric pressure applied hence even at mean sea level it may or may not boil at exactly 100 degrees C as this is dependant on the atmospheric pressure at the time of the experiment. And as the mineral content of any water will affect its BP for the basis of this answer it will be assumed that the water in question is distilled... and on and on.

I will point out that to become a sparky you need only need 4 GCSE's at level 4 including maths and English to take the 1 A level equivalent C&G level 3.

If you want to interpret things at least get enough of a education to be able to do that.

 

[JohnW2]

A bit like the conspiracy theorists really.
People tend to take no notice of them because of some of the insane theories they come up with by by misinformation or exaggeration to such an extent that when they might actually mention something which does ring true in full or in part we might might have a tendency to disregard it anyway because of who said it.

That is obviously the concern I have voiced.

Mind you, the 'not making sense' does not seem to make sense There are obviously going to be countless employees of DNOs who do understand that an OPD will give protection to the entire length of a single cable downstream of it, regardless of that cable's length, so one can but presume that there must be some other 'thinking', that has so far escaped all of us, for the existence of the rule/regulation we've been discussing.

Even in terms of JohnD's valid comment that the longer the 'tails', the more likely is it that some will be concealed/buried does not really afford an explanation, since the DNOs fuse would offer no less protection than a consumer's fuse of same rating installed next to it!

 

[JohnW2]

My two pennies worth is that the industry needs to make up "regulations" or advice as its known due to the intellectual calibre of those its intended to guide.

Yes, that's fair enough, but is that not even more reason why they should not make up 'regulations' which appear to make absolutely no sense in terms of the fundamental electrical principles underlying the industry?

 

[EFLImpudence]

since the DNOs fuse would offer no less protection than a consumer's fuse of same rating installed next to it!

Or indeed one of a higher rating.

60A DNO fuse and someone has fitted 25mm² tails - because that's what it says in the OSG and people just do - so could have a 100A fuse.

 

[martygturner]

Yes, that's fair enough, but is that not even more reason why they should not make up 'regulations' which appear to make absolutely no sense in terms of the fundamental electrical principles underlying the industry?

That's the point, they do make sense when you base you regulation on another set of assumptions... in lots of cases. There is a degradation of confidence of that regulation as the basic assumptions are excluded, just instead the new regulation is presented without its assumptions leading to confusion as people try to reverse engineer the issue and its principles from the regulation, without those principles on which the regulation being stated is derived from.

For example do the IET include all its assumptions on the overall state of the grid.... or has it just decided to go its 230v nominal when we all know we can have a bit of a variation to that, I get 243v... who recalculates anything to take account of the actual voltage at a property ?

Its a common problem across all applied science.

From my own field,

The Environment Agency must have regard to the following maximum doses to individuals (dose constraint) which may result from a defined source, for use at the planning stage in radiological protection(Schedule 23, Part 4, paragraph 2): 0.3 mSv/year from any source from which radioactive discharges are made; or 0.5 mSv/year from the discharges from any single site.

Which is derived from a 1952 study when access to contaminated people rather than models was available to calculate the maximum yearly radiation dose.

Except this is rather b llocks, as the '52 study concerned itself with the maximum dose before death...so we have a regulation on the dose we can take without harm based on a study that look at the maximum dose for death...except where is the definition of harm ? is harm only an untimely death or is it cellular death ( burns etc) or is it generic mutations eg cancers ?

So its a regulation that makes no sense when looking at what its based on... but its still the best possible rule of thumb to not irradiating yourself at work, well we hope.

And that is the issue with the IET, it shows some of its assumptions and glosses over others or takes its own assumptions and reapplies these to new situations, but again its the best at present... in my case we would need conduct a study by deliberately irradiating people with increasing doses... or shall we stick with the best guess.

Basically regulation can be a right fudge up...

 

[JohnW2]

Or indeed one of a higher rating. 60A DNO fuse and someone has fitted 25mm² tails - because that's what it says in the OSG and people just do - so could have a 100A fuse.

As I said, I have that very situation here - 3 x 60A DNO fuses followed by 3 x 80A switch-fuses of mine (albeit a bit over 3m 'as the cable flies' from the meter!)

 

[JohnW2]

That's the point, they do make sense when you base you regulation on another set of assumptions... in lots of cases. There is a degradation of confidence of that regulation as the basic assumptions are excluded, just instead the new regulation is presented without its assumptions leading to confusion as people try to reverse engineer the issue and its principles from the regulation, without those principles on which the regulation being stated is derived from.

I still don't get it, in this particular case. What 'assumptions' could possibly result in a suggestion that an OPD which provided adequate overcurrent protection for a 2m or 3m length of downstream cable would not also provide the same degree of protection if the cable were 4m (or even 40m) long?

 

[martygturner]

nor do I but what were their assumptions ? Did they include a fudge of at 4m its assumed there are 4 x 90 degree bends in the cable because they assume 1 in 2m, did they assume that a cable of 2m will not require a thermal load calculation but a 4m one will ?

 

[JohnW2]

nor do I but what were their assumptions ?

As I've said and implied, I do not think that any assumptions could alter the Laws of Physics we are talking about - can you think of any?

Did they include a fudge of at 4m its assumed there are 4 x 90 degree bends in the cable because they assume 1 in 2m, did they assume that a cable of 2m will not require a thermal load calculation but a 4m one will ?

What do you mean by a 'thermal load calculation' (which you seem to imply is affected by bends in the cable)?

 

[martygturner]

No, they are separate but the could be together, as I have no knowledge of what assumptions they made..

Does 4m at 100 amps max cross a line somewhere where 2m does not in terms of bends, are they taking it that 2m has limited bend potential...

They could be taking it that a cable greater than 2m will have the capacity to be buried and therefore not visible, thus requiring protection...they could have just read across from their other regs, cables being buried at less than 50mm need additional protection, have they assumed that and are giving a back handed get out to use armoured to the CU...

Is it an IET thing or a cable manufacturing thing, has the spec for the cable changed.

That's the issue with reverse engineering an answer, unless you know what was in the mind of the designer and the assumptions they used...

Sorry missed the thermal load bit...we always calculate the maximum thermal load of a cable as its different to its carrying capacity, whilst you may squirt say 50amps down a 80amp rated cable and its stable with no thermal damage ever, pulse the same cable at say 90% its rating a few times and you get thermal hot spots appearing on the insulation. Again that won't be an issue under normal circumstances it cools back and hey ho no breakdown, but then you get to a large fault say now the cable is a 300% its rating whilst you wait for the failsafe to operate and you get degradation of the insulation. Unless you can constantly check the insulation resistance you could have a possible fault sat there waiting for the next event.

So the thermal load of the cable is calculated to give an indication of its lifespans in operation, not for its thermal help I am on fire but to asses its longevity and plan maintenance.

 

[JohnW2]

No, they are separate but the could be together, as I have no knowledge of what assumptions they made..

As I said, I can personally think of no assumptions that would result in their 'regulation' making sense.

Does 4m at 100 amps max cross a line somewhere where 2m does not in terms of bends, are they taking it that 2m has limited bend potential...

Again, I've never heard of bends in cables being considered in relation to current-carrying capacity (hence 'protection requirements').

They could be taking it that a cable greater than 2m will have the capacity to be buried and therefore not visible, thus requiring protection...they could have just rdea across from their other regs, cables being buried at less than 50mm need additional protection, have they assumed that and are giving a back handed get out to use armoured to the CU...

It doesn't really matter whether the cable is visible or buried, armoured or not armoured, of whatever length or even if 'bends' are somehow relevant because, regardless of all that, it still makes no sense to suggest that their fuse might not give adequate protection to a particular cable (any cable, installed in any way) but that a consumer's identical fuse immediately adjacent (electrically) to theirs would.

 

[morqthana]

And, in turn, I have agreed with all those points.

However, I have also made the different/additional point that I believe there are good and important reasons (which "matter") why DNOs should not be creating regulations which make no sense in terms of the indisputable fundamental scientific principles which underlie everything which happens in their industry - behaviour which is bound to result in some people questioning whether one can 'take seriously' anything they say or do.

I agree with everything you say about the general principle of it being desirable for laws/rules/regulations to make sense, as that tends to get the most, and least resentful, compliance, and tends to avoid laws/rules/regulations which have no beneficial effects,

But re all I've been trying to say here, all I can do is to give this example, of two people talking

A: "I'm going to do XYZ"
B: "You can't do that, it's against the law"
A: "That doesn't make any sense"
B: "Doesn't matter"

I would never think that what B was doing was taking a position in an argument about the "philosophy" of laws/rules/regulations having to make sense.

I would always think that what B was doing was pointing out to A that it didn't matter that he thought the law made no sense, he still couldn't do XYZ.

But it seems I'm the only one.