What makes you think they are not appropriate values?
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5A BS 1363 plug?
- Thread starter ericmark
- Start date
About the assumption (that JohnW2 implied) that the fuse values were those to be used for the tests.
Both Table 2 of BS1363 and Table 4F3A of BS7671 giving the 'current rating'/CCC of 0.75mm² flex as 6A and the 'current rating'/CCC of 1.0mm² flex as 10A. Is it naive of me to therefore assume (in the way one would work in almost any design situation) that a 13A fuse was not 'appropriate' for protecting either of them?
Kind Regards, John
Yes, it is, since Table 2 also tells you that a 13A fuse shall be used. In 'almost any design situation' the first thing to do is to read the specification!
Those ratings wouldn't generally be allowed by better standards, such as IEC (BS EN)60204-1 though.
I was doing more than implying about BAS's expressed interpretation (which, as I'm said, I can't blame him for, given the title of Table 2 - with it's invisible, but apparently 'implicit', comma!):
Kind Regards, John
I can only agree with you in the sense that "that it what is says, and therefore I have to blindly accept it". I don't know if I'm just being dim, or what, but it seems extraordinary to me that a single Table should at the same time indicate the ('maximum') 'current rating' of a cable and an 'appropriate' fuse rating which is greater than that stated maximum current rating of the cable. As you know, BS7671 would not 'allow' 0.75mm² or 1.0mm² flex to be protected only by a 13A OPD, so why does BS1363? Physics is surely the same for all BSI-related committees?
Kind Regards, John
About the assumption (that JohnW2 implied) that the fuse values were those to be used for the tests.[/quote]
I didn't assume that.
I think it's you and he who are making incorrect assumptions.
I didn't assume that.
I think it's you and he who are making incorrect assumptions.
No, you don't have to blindly accept whatever you're told by a specification, indeed an engineering approach would be correct to question something that seems technically incorrect to you. However, you're making some assumptions again; Table 2 of 1363 does not indicate the maximum rating of anything. A rating is defined as "a value assigned by a manufacturer". (The term has other uses, but let's not go there.) What the Table is therefore telling you is that if you make a cordset that has say a 0,75 mm2 cable then you shall not rate it greater than 6A, you shall test it (in accordance with the standard) at 7A, and you shall fit it with a fuse 'rated' at 13A. It is not telling you what the CCC of 0,75mm2 cable is, and has no relevance to other applications of such cable, just as 7671 has no relevance other than in the context of electrical installations.
I hadn't seen BAS' explanation in the other thread, but I agree, except that the Table does other things than describe test conditions. The column headers are more informative than the Table title and explain (to me at least) my 'implicit' comma.
I hadn't seen BAS' explanation in the other thread, but I agree, except that the Table does other things than describe test conditions. The column headers are more informative than the Table title and explain (to me at least) my 'implicit' comma.
[give or take the abomination of formatting, which I've had to partially correct above!]
In that case, I'm lost - what did you mean when you wrote:
?
Kind Regards, John
OK.
Fair enough. I suppose that I'll therefore have to 'accept' that it is a pure co-incidence that those stated 'current ratings' in 1363 for those cables just happen to be identical to the CCCs for the same cables as specified in 7671.
I'm personally not convinced. BAS's interpretation (without assuming an implicit comma) seemed very rational. As he said, if one wishes to undertake tests at test currents of 7A and 11A, and IF one only 'recognises' the BS1363-specified 3A and 13A fuses, then it follows that one has to use 13A fuses for those tests, and that would be the case even if (as I believe to be the case) a 13A fuse would not be appropriate 'in-service' for those two cable sizes.
Kind Regards, John
There you go again. BS1363 is not stating current ratings for those cables. It is making a statement about what shall be done when a cable has that rating.
I know it is. However, I have limited sources of information about cable characteristics, and therefore rely on what BS7671 tells me about the 'CCCs' of the cables and hence, in turn, what over-current protection is appropriate for those cables - so, to me, the column in BS1363's Table 2 headed "Rated Current" (which contains identical figures to BS7671's 'CCCs') is effectively the 'CCCs' of those cables as I know them.
Furthermore, I'm a bit confused when you say that BS1363 "is not stating current ratings for those cables". If is not, then what does column which is headed "Rated Current" in Table 2 represent? Am I perhaps missing some subtle difference between 'Current Rating" and "Rated Current"?
Kind Regards, John
And again. BS7671 tells you what CCCs are acceptable for those cables when used under defined conditions, in an electrical installation. BS1363 is telling you that a cordset rated at 6A shall use 0,75mm2 cable and a 13A fuse. Life is not as simple as each CSA of cable having a single current carrying capacity.
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The first transatlantic transmission comes to mind "what hath god wrought" but be is 0.5mm², 0.75mm² or 50mm² the "XD RVV WGX3C PVC WIRE GP" written on the cable does not help.
I will guess it's an American standard of some type and some one in America would be able to tell us what it means. But we do not live in America.
So we have a cable marked 5A one end and 10A the other end and no idea as to when PAT tested it should pass or fail or what fuse should be fitted.
Before this post I have never looked at plugs to read the amp rating. The socket yes a cloverleaf socket is rated 2.5A so clearly needs a 3A or less fuse.
So naturally I would see the socket is rated 10A and fit a 10A fuse but until this post I would not even inspect the plug to see if there is a rating on the plug.
OK in future I will but if it requires two pairs of glasses to read it then forget it. Taking a photo then cropping and blowing up with Photoshop should not be required.
Asking my father-in-law he could see it was a 13A plug and also read the fuse which said 5A made in England but the moulded 5A and 10A markings he could not read.
be it clover leaf or figure of 8 we all know the rating even if we can't read it but with a 10A socket I would have expected the 5A marking to at least be in a different colour.
I will guess it's an American standard of some type and some one in America would be able to tell us what it means. But we do not live in America.
So we have a cable marked 5A one end and 10A the other end and no idea as to when PAT tested it should pass or fail or what fuse should be fitted.
Before this post I have never looked at plugs to read the amp rating. The socket yes a cloverleaf socket is rated 2.5A so clearly needs a 3A or less fuse.
So naturally I would see the socket is rated 10A and fit a 10A fuse but until this post I would not even inspect the plug to see if there is a rating on the plug.
OK in future I will but if it requires two pairs of glasses to read it then forget it. Taking a photo then cropping and blowing up with Photoshop should not be required.
Asking my father-in-law he could see it was a 13A plug and also read the fuse which said 5A made in England but the moulded 5A and 10A markings he could not read.
be it clover leaf or figure of 8 we all know the rating even if we can't read it but with a 10A socket I would have expected the 5A marking to at least be in a different colour.
I guess I'm just going to have to remain confused!
I'm not really sure what 'rated at 6A' (in relation to a cordset) really means if it doesn't mean that it is deemed 'unsafe' for it to carry more than 6A, in which case, I would expect the required protective device to reflect that. Nor do I really understand why the 'CCCs' (the maximum current deemed to be 'safe') of a flexible cable of a given CSA should be appreciably different if it is part of an electrical installation or part of a moulded 'cordset' - indeed, if anything, I would expect the CCC (hence In of required protective device) to be lower for the latter, given the sort of treatment it might receive in service.
There must be some logic, and maybe even empirical data, behind all this - but it currently just mystifies me!
Kind Regards, John
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