Hi Chris, its nothing to do with any countries typical ambient temperature, its simply a fixed testing baseline control point.
In the case of fuses (as that’s the thread topic) but also all electrical ratings (watts/amperes) the amp rating number is set when the item under test rises by 1’C and then stabilises from the 30’C baseline.
Sure, but I question the logic of FZ’s quote that, “the 30°C temerature the tests are conducted at is unlikely to be achieved in the UK climate”.
Well it depends when the standard was written. Also it depends on the definition of “unlikely”. On any given day then yes, it’s unlikely. If it means unlikely to ever happen, then of course it’s wrong. It has done, and will continue to hit those daytime highs from time to time during the year… Though again, as a percentage of time of the entire year, then it might still fall into “unlikely” territory. There’s a lot we don’t know.
Worth pointing out, the final paragraph of the page I lifted quotes from has a conclusion that states (paraphrased) that while a fused plug is, in their opinion, unnecessary, it’s a moot point because it’s the law and that’s all that matters.
OK gotcha, your post triggered a notification to me.
Would members please note that only discussion of plug fuses is OK here (within limits), and so only really applicable in the UK and a few other countries. Discussion of non-standard fuses inside equipment is strictly forbidden here.
Ha! Richard, I was wondering when you would step in.
I must admit I was testing to see if you are paying attention. 
Difficult to argue with this from personal experience. How many 13A plug fuses have you had to change in the last 12 months? How many would you have had to change over an equivalent 12-month period back in, say, the early 80s?
I suppose we have to discuss moving technology but bear in mind by law and legislation UK and some have to confirm for building regs and fire safety compliance and home insurance.
I’ve no qualms about home safety I’m a bit obsessed by it. 
Not sure if this is a joke or you are serious.
If you meant it seriously then just give some careful logical thought to what you have said and then ask yourself if it really makes any sense.
Some peoples problem with accepting that fuses are directional is based on the fact that it’s alternating current.
Alternating current is the current flowing from one direction , reaching a peak force, decelerating until it stops, and then reversing direction until it reaches another peak force at which time it slows down and again stops.
I don’t know why my fuse sounded different when plugged in a different direction. And that was the puzzling thing of this whole thread. 
Even the speaker cables plugged in the wrong direction sound different but at least I can offer an explanation for that - that the cable is formed in one direction therefore somehow gaining polarity.
It makes perfect sense to me. I am quite certain that fuses are not directional.
My physics is way out of date and probably very shaky now, but despite it being AC it still propagates in one direction, ie. from a point of higher to lower potential. So the view that wires of any sort cannot be directional with regard to AC doesn’t hold up even on the most basic elementary physics, never mind anything else such as the effects of insulation etc.
How so?
Every extruded item has a direction vector.
Has to mean something in the usability of the intended structure. 
Out of interest, how can you be certain that unconscious bias is not at play? Please don’t tell me it’s because you can hear the difference.
I have read articles that confirm this but not being an engineer i will refrain from offering an explanation.
We cannot be certain that unconscious bias doesn’t play a part. But then why is this argument only in the case of a fuse. Why do we not have the same attitude for speakers or amplifiers. Let me guess because they “measure” differently. Ok but how much of those measurements fall into our hearing ability spectrum?
And yet again if they fall into our hearing spectrum and the measurements confirm differences in sound how can we be certain that it isn’t unconscious bias. You see we can play this game all day but I prefer to enjoy the hobby rather than twist myself in loops.
I will continue by saying that we accept our multiple sense perception in everything else. Whether that is tasting food or test driving a car. But suddenly for hifi we should accept that we cannot introduce another sense other than our hearing ability to make a judgement.
I will strongly argue that double blind testing introduces a bias. As the listener will continue to second guess himself which leads to confusion rather than clarity. I’ve mentioned this before that dr Floyde toole of Harman suggests listening to a single speaker rather than stereo if one is to judge a speaker accurately. Not only this but it should be a double blind test. When hifi enthusiasts carry out this method of auditioning then I will stop with my agenda of refuting the ‘scientists’ or objective listeners amongst us.
That last comment is a little silly as there is no such thing as an objective listener. It’s all subjective but I mean to say listeners that only approve of measurements.
Ditto. Please don’t tell me it’s because you can’t hear the difference.
Moreover, why does this argument only work one way? ie. why are people who hear differences in cases like this mistaken due to the effects of unconcious bias, expectation bias or whatever? Why don’t the effects of unconcious bias or expectation bias or whatever apply equally to the people who say that others are mistaken due to this.
The reality is that if unconcious bias or expectation bias or whatever actually does play a part in our evaluation of what we hear then we are all equally subject to it.
Anyone who claims that fuses are not directional has no more validity than those who say they are. And no less.
The difference between my approach and the approach of the majority of people who cite ‘bias’ of one kind or another, is that I don’t try to persuade them that they can’t believe their own ears.