BS1362 includes 1A fuses.
PIV electrics
- Thread starter BRIGHTHOPE
- Start date
Of course, my mistake.
So, you cannot afford protection below a 1A fuse - plus its fusing factor?.
So, you cannot afford protection below a 1A fuse - plus its fusing factor?.
I don't think anyone is suggesting that the flexible cord of an appliance is not fully protected by the preferred value BS1362 fuses, so I don't see the relevance of that quote from the BEAMA paper.
As neither of you has given an example of an item where this would be beneficial, might a 3A or 1A fuse save me having to spend another 8 euros on a new glue gun?
I don't see how the type of fuse has any relevance.
I doubt it, for a number of reasons, one of which is that you'd have nowhere to fit it! At that price, it presumably contains only a heater so would be unlikely to benefit from a lower value fuse than is necessary to protect the flex.
I find that very surprising.
I would have thought that the possibility, even if only small, of reducing damage (including fire) would count as 'beneficial', wouldn't it.
Let's try a different approach ...
... I think (maybe wrongly!) that we are all agreed that appliances/equipment should have adequate (ideally 'optimal') internal protection against over-current. If that is agreed, then the question that you perhaps should be asking yourself is "Why?". If you, and the manufacturers don't believe that limiting the let-through current can/might reduce damage (and fire risk) why on earth would they/you bother about installing any internal protection?.
If it can be agreed that there is a 'good reason' for manufacturers to install adequate (or 'optimal') internal protection in their products, then all I'm saying is that if a load does not have such internal protection, or if it may not (i.e. one does not know for sure), then it seems to make sense to provide that protection externally - for the same 'good reasons' that manufacturers would/should install it internally (if they did).
As I've said, if one is sure that adequate internal protection is in place (as is probably the case with, say, a TV), then it doesn't matter what external protection, if any, is provided - were it not for the fact that, in the UK, we have to put some sort of fuse in a BS1363 plug, we would not need any fuse in that situation (assuming that the circuit as a whole provided adequate fault protection).
Kind Regards, John
Oh, it's an example of an 'item' you're after is it, rather than an example of when a low-rating fuse has done good?
The problem in terms of things I own is that, in many cases, I would virtually need a tin opener to ascertain whether they contain adequate internal protection - so, in such cases, I take the conservative approach of assuming that they don't.
Kind Regards, John
A further consideration is what is meant by 'adequate' internal protection. Is protection sufficient for 100% of cases, or 99%, or 90%? What if the appliance is such that any overcurrent sufficient to blow a fuse will have caused irreparable damage to the appliance?
Indeed - that why I have recently been writing "adequate (ideally optimal) internal protection".
Kind Regards, John
Well, neither you nor BAS has given an example of an instance where it would be harmful to fit a lower value plug fuse...
What do you consider to be adequate or optimal?
Ah.
It would - but you are continuing to believe that that is not already the case.
Yes, why wrongly?
Which items below 3A or 5A can cause enough overload to blow that rating of fuse?
Did you, yourself, not calculate that an extractor fan could not?
Why do you assume the ones that can (if there are any) don't have adequate protection?
Why what?
My, this getting convoluted.
So, you are now saying the manufactuer has already adequately protected their product.
The question is - does installing a lower rated fuse do anything beneficial on top of the internal protection?
Then why wouldn't they have installed it.
Are you saying that these things catch fire in the rest of the world but they just don't mind?
So, you think that despite it being needed some items do not have it and these things catch fire in the rest of the world but they just don't mind.
Therefore the fact that you would not need any fuse in that situation must mean that it is irrelevant.
Don't be silly, neither of us has said it would be harmful.
We are trying to get you and John to give an example of where it would be beneficial.
I'm saying that if one does not know for sure that there is 'optimal' internal protection, the conservative approach is to assume that it may not have such protection.
Indeed - IF there is internal protection .... and the answer is that installing a lower rated fuse will be potentially 'beneficial' IF the internal protection is 'sub-optimal' (i.e. higher-rated fuse than would allow functioning of the equipment), or non-existant.
Indeed, as I keep saying (initially on page 1), and as I said again in my last post (part of which you quoted), IF there is optimal internal protection then, as you say, external protection is irrelevant.
Kind Regards, John
'Adequate' is a matter of opinion, since it is 'sub-optimal'.
I would say that, as per the whole thrust of this discussion, 'optimal' refers to the situation when the rating of the fuse is the lowest (available) that allows the equipment to work.
When I suggested that I found it hard to believe that any LED TV would require a 10A (external) fuse, you told me that the manufacturer will know better than I what fuse is needed. However, you also said that manufacturers want to avoid warranty claims due to blown fuses, and therefore by implication are likely to err on the side of a higher fuse rating. If that is true of the plug fuse, I imagine it is even more true of internal fuses, since one of them blowing definitely would result in a warranty claim (whereas the owner might replace a blown plug fuse). hence, you seem to have implied that (because of warranty considerations), internal protection may often be 'sub-optimal'.
EFLI's 180W LED TV is an example. I know you'll probably tell me that the manufacturer knows better than I do, but I really do find it hard to believe that a 180W LED TV would ever blow a 3A fuse (and quite probably not a 2A or 1A one), even at switch-on, yet it appears that the manufacturer has installed an internal 6.3A fuse. If I owned that TV, and knew that it had a 6.3A internal fuse, I would regard that as 'sub-optimal' internal protection and therefore would put a 3A (or maybe smaller) fuse in the plug.
Kind Regards, John
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