Why don't lamps come with a 1 amp fuse in the plugs?

[ban-all-sheds]

The 2metre unterminated one seems to be the only one 13 amp rated

There ya go.

 

[JohnW2]

You're all missing the point.

I don't believe that I am.

Yes - it does intuitively seem that a C13/14 or C15/16 pair could cope with 13A, but intuition (rightly, IMO) is not what standards are based on.

I agree totally, and have not suggested otherwise. I merely agreed with rocky (and you) about the intuitive view.

And the standard requires that it only be capable of carrying 10A.

I feel sure that no Standard would say quite that! It might well say it is 'rated' for a maximum of 10A and/or that it should not be used to carry a current of more than 10A, but it would be daft for a Standard to 'require' that it was "only capable" of carrying 10A. However, I presume we are agreed that it should not be used to carry a current greater than 10A, because (for whatever reason) it is not required (by the Standard) to be able to cope with more than that.

But what there must be is a requirement for them to not be used for a load which in normal operation is more than 10A, hence the rating given by the makers. ...

As above, totally agreed.

However, all of the above is different from a requirement that such a connector be protected by a 10a fuse (which is what Simon implied) - apart from anything else, as you say, it would be impossible to satisfy that requirement in most countries other than the UK. Even in the UK, I am not aware of any requirement that connectors be 'protected' by OPDs, and if there was a thought of trying to use a fuse to 'limit' the current that people could try to draw through the connector for an appreciable period of time to 10A, I need not tell you that the maximum permitted fuse rating would probably have to be 5A or lower.

People can/should be told that they should not use such a connector to carry more than 10A, but there is no practical or sensible way that one could use (in the manner that Simon seemed to be implying) a fuse in an attempt to 'enforce' such a requirement.

Kind Regards, John

 

[ericmark]

What seems common is to state the fuse protects the cable. As to the connector on the end of that cable to me they should also be protected by the fuse.

So a 2.5A connector even if moulded onto a 1.25mm² cable should still have a 2A fuse not a 13A fuse even though a 13A fuse would protect the cable.

The same other way around a 10A connector on a 0.75mm² cable the fuse should be still 6A.

I don't know why 0.5mm² cable is listed (3A) as Table 52.3 lists nothing under 0.75mm²?

OK maybe china still supplies 0.5mm² but it is not worth going into non compliant items.

To me the problem is a moulded plug and connector where there is no writing on the cable to show it's size. This is common with cables designed for computers the 13A plug with two 10A connectors is a common problem since there is resistance in the fuse it is impossible to test to find the cross sectional area of the cable inside without first measuring length and resistance of the fuse.

So if no cable size is printed on the cable then I suppose we should fit a 3A fuse. My kettle is what is called cordless and there is no cable size shown however I would always fit a 13A fuse even though really I have no idea of the cable size.

 

[JohnW2]

What seems common is to state the fuse protects the cable. As to the connector on the end of that cable to me they should also be protected by the fuse. ... So a 2.5A connector even if moulded onto a 1.25mm² cable should still have a 2A fuse not a 13A fuse even though a 13A fuse would protect the cable.

Quite apart from the fact that, as I have said, I am unaware of any actual 'requirement' to provide connectors (or anything else, other than cables) with over-current protection, I'm not sure how one would work out exactly how to achieve it - so I'm not sure that the figures you suggest are necessarily correct.

In the case of cables, the 'CCC' tables we use are constructed to take into account the known characteristics of the cable - e.g. that a cable is deemed to be able to safely carry 1.45 times its tabulated CCC for an hour. We therefore know that the cable will be 'safe' if protected by a Type B MCB whose In is no greater than that 'tabulated CCC'.

However, I don't know about you, but I haven't got a clue as to how long a connector can safely carry how much more than its 'rated current'. Accordingly, using your example, a 2A fuse (which would probably allow ~4A to flow for quite a while) might well, for all I know, not give adequate 'protection' to a "2.5A connector". If we are to be expected to use OPDs to protect connectors, then we would need to have knowledge of the 'over-current tolerance' of the connector, so that we could match it to the characteristics of an OPD - to determine what rating of OPD would be required to give adequate protection.

Kind Regards, John

 

[EFLImpudence]

I don't know why 0.5mm² cable is listed (3A) as Table 52.3 lists nothing under 0.75mm²?

Yes, it does - twice.

As has been said before, Table 52.3 is an enigma.

 

[ericmark]

A 2200W kettle is 10A and all the 3000W kettles I can find are classed as cordless so don't use a C15A IEC 60320 connector. The old

connector I can find no info as to rating. Although described as "Universal 13 Amp Round Pin Kettle Plug Element Connector & Cable Grommet".

As to fitting a 10A fuse in a C15A IEC 60320 connector attached to a 13A plug yes it would seem correct but if I was doing a inspection of in-service electrical equipment and a 13A fuse was fitted I would not change it or fail it.

So down to nitty gritty that's the real question. When doing a inspection and testing of in-service electrical equipment what would be the result pass or fail there is no other option either it passes or fails so with all which has been talked about what would you fail on an inspection and test.

 

[JohnW2]

To me the problem is a moulded plug and connector where there is no writing on the cable to show it's size. This is common with cables designed for computers the 13A plug with two 10A connectors is a common problem since there is resistance in the fuse it is impossible to test to find the cross sectional area of the cable inside without first measuring length and resistance of the fuse.

If you measured the resistance of the neutral conductor, you would avoid that (fuse) problem. Whether your meter would be able to measure the resistance of a metre or two of conductor accurately enough to enable you to distinguish confidently between, say 1.0, 1.25 and 1.5 mm² might be a different matter.

Kind Regards, John

 

[ban-all-sheds]

What seems common is to state the fuse protects the cable.

Yes.

From faults.

As to the connector on the end of that cable to me they should also be protected by the fuse.

Yes.

From faults.

So a 2.5A connector even if moulded onto a 1.25mm² cable should still have a 2A fuse not a 13A fuse even though a 13A fuse would protect the cable.

Would a 13A fuse not protect it from faults?

The same other way around a 10A connector on a 0.75mm² cable the fuse should be still 6A.

Why? Would a 13A fuse not protect the cable from faults?

I don't know why 0.5mm² cable is listed (3A) as Table 52.3 lists nothing under 0.75mm²?

Because it is made and because some appliances use it?

OK maybe china still supplies 0.5mm² but it is not worth going into non compliant items.

To me the problem is a moulded plug and connector where there is no writing on the cable to show it's size. This is common with cables designed for computers the 13A plug with two 10A connectors is a common problem since there is resistance in the fuse it is impossible to test to find the cross sectional area of the cable inside without first measuring length and resistance of the fuse.

So measure the resistance of the N or CPC.

So if no cable size is printed on the cable then I suppose we should fit a 3A fuse.

Why? How small would the cable have to be for it not to be adequately protected from faults by a 13A fuse? Or a 10A, if you insist?

My kettle is what is called cordless and there is no cable size shown however I would always fit a 13A fuse even though really I have no idea of the cable size.

I'm sure if you look under the base you'll find something which tells you what the load of the kettle is, and therefore will inform you of the wisdom of using a fuse <13A. Mine draws 12A at U0, so I'd be pretty foolish to not use a 13A fuse. And although mine was made in China it was for a reputable European maker, and bought from a reputable UK High St retailer, so short of cutting the plug off to measure the conductor size I've done all that I can to ensure that the cable is at least 1.25mm²

 

[JohnW2]

The old

connector I can find no info as to rating. Although described as "Universal 13 Amp Round Pin Kettle Plug Element Connector & Cable Grommet".

Although not the best of images, it is, indeed, clearly marked "13A" but I can't confidently read all of the BS number.....

Untitled

• JohnW2
• 9 Jan 2015
• 1

Kind Regards, John

 

[ban-all-sheds]

Whether your meter would be able to measure the resistance of a metre or two of conductor accurately enough to enable you to distinguish confidently between, say 1.0, 1.25 and 1.5 mm² might be a different matter.

It's about 6m&#937;/m difference between 1.0 & 1.5, so presumably about half that between 0.75 and 1.0, which is where the "OK for a 10A load" inflection point is, so yes, you'd need an accurate meter, a guarantee of clean connections, and without a reference cable to compare, an accurate thermometer too. Probably be just as accurate to measure the OD.

 

[JohnW2]

Whether your meter would be able to measure the resistance of a metre or two of conductor accurately enough to enable you to distinguish confidently between, say 1.0, 1.25 and 1.5 mm² might be a different matter.

It's about 6m&#937;/m difference between 1.0 & 1.5, so presumably about half that between 0.75 and 1.0, which is where the "OK for a 10A load" inflection point is, so yes, you'd need an accurate meter, a guarantee of clean connections, and without a reference cable to compare, an accurate thermometer too. Probably be just as accurate to measure the OD.

Exactly.

Kind Regards, John

 

[EddieM]

6 pages...

 

[JohnW2]

6 pages...

... and I suspect that this one might well make it 7
Edit: damnit - counted wrong

Kind Regards, John

 

[ban-all-sheds]

Nearly there...

 

[ban-all-sheds]

Not long now....