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

[JohnW2]

In the past I used 1A fuses for lamps and found whenever a bulb blew the fuse did too, doubling the cost, so I went back to 3A. With today's CFL and LED lamps one could I suppose reconsider.

As I've said, despite that being the context of the OP, I probably wouldn't personally use a 1A fuse for incandescent lighting, because of the 'risk' you mention. As I've said, my comments, and my personal usage of 1A fuses, mainly relate to 'small electronic devices' - and, unless you can point out something I haven't thought of, I really don't see any downside of that.

Kind Regards, John

 

[JohnW2]

Am i missing something or can anyone see a problem using the 10 amp 1.5 leads with moulded plug, cutting the socket off and using a 13 amp fuse

I can't see how there could ever be a problem in having 1.5mm² flex (or even a 1.25mm² one) protected by a 13A fuse, per se. So, provided that the manufacturer of the appliance didn't insist on a 10A fuse (and, even that not necessarily under Amd3!), and that you yourself did not see a reason why it had to be a 10A fuse, I can't see how there could be any sort of problem.

Kind Regards, John

 

[SimonH2]

for example the kettle lead is rated 10A.

Why is this when the cable is often 1.5

The C13/C14 connectors are only rated for 10A.
Additionally, the standard cable sockets are not rated for hot applications - that's why there's a version with a keyway in the bottom of the socket (between the L&N pins). The hot service lead will fit a standard inlet, but a standard socket won't fit a hot-service inlet (eg kettle).

 

[333rocky333]

Thanks john, most of our damaged leads are on commercial catering equipment originally fitted with 13 amp fuses when new.

I quess in the real world quite a few of these so called kettle leads with 10 amp plug fuses get replaced with the more easily obtainable 13 amp fuse anyway.

Recently ive seen a few melted moulded plugs though,
I would have thought moulded plugs were all made standard to take a maximum of at least 13 amp, even the ones on 10amp leads, surely they wouldnt rate some moulded plugs at 10 amp max would they.

 

[333rocky333]

The C13/C14 connectors are only rated for 10A.
.

Thanks thats the only reason I could see.
Seems odd to me why they are though.

 

[JohnW2]

for example the kettle lead is rated 10A.

Why is this when the cable is often 1.5

The C13/C14 connectors are only rated for 10A.

If the load is ≤10A and the nature of the load is such that it is "unlikley to create an overload" (i.e. result in a current >10A, other than true, very high, 'fault' currents), I would not have thought that would be a requirement to have a 10A fuse, even if the connectors were only rated at 10A, provided the fuse fitted (e.g. 13A) was adequate to protect the cable (which it would be for any flex ≥1.25mm²), would there?

Kind Regards, John

 

[JohnW2]

The C13/C14 connectors are only rated for 10A..

Thanks thats the only reason I could see. Seems odd to me why they are though.

As I've just written, I'm far from convinced that that, per se, is a reason for needing a 10A fuse. I also agree that it seems very odd/unlikley that they can't 'cope' with at least 13A!

Kind Regards, John

 

[333rocky333]

The hot service lead will fit a standard inlet, but a standard socket won't fit a hot-service inlet (eg kettle).

I never new that till recently, a socket on a lead for a plate warmer had melted and i tried to temporary use a computer lead

 

[ban-all-sheds]

I can get 10 amp rated leads in reasonable lengths but 13 amp rated ones are short and sparse, however they generally both are 1.5 cable.

Well - if the maker has used 1.5mm² cable which does comply with BS 6700 or the equivalent EN#####, then it would have to be limited to 60° operation and be used with an ambient temperature exceeding 45°C for it to be rated at only 10A.

So either they are not using proper cable, or they don't know what they are talking about.

Or their 10A rating for their integrated lead, with a BS 1363 plug on one end and an IEC 60320 connector on the other, correctly reflects the fact that only C19, 21 & 23 connectors are rated at more than 10A. The common C13 & C15 "kettle" connectors are only 10A, the C7 "figure-of-8" and the C5 "clover leaf" or "Mickey Mouse" are only 2.5A, and so on.

You say "we often get 13 amp fuse rated appliances, where the lead gets damaged" - to me that implies some kind of commercial environment, so given the amount of fake and dangerous tat coming out of China these days you ought to be doing due diligence on the actual cable used, checking for BASEC certification etc. Under normal circumstances 1.5mm² flexible cable is good for 16A.

 

[ban-all-sheds]

Recently ive seen a few melted moulded plugs though,
I would have thought moulded plugs were all made standard to take a maximum of at least 13 amp, even the ones on 10amp leads,

AFAIK there is no option in BS 1363 to make plugs which cannot handle 13A even if you state that they are so limited.

surely they wouldnt rate some moulded plugs at 10 amp max would they.

There are no limits to what the Chinese makers of dangerous fake tat will do,

 

[333rocky333]

Thanks Ban
The damage is wear and tear usually insulation accidentally severed, etc.
The leads I get are from RS components so hopefully not chinese tat.
I wouldnt chance ebay leads

http://uk.rs-online.com/web/c/cables-wires/electrical-power-industrial-cable/power-cable-assemblies/

The 2metre unterminated one seems to be the only one 13 amp rated and the one I tend to keep as stock

Its only special cases where the catering company cant attend for a few days, and where its a straight forward replacement, we dont make a habit of it.

 

[JohnW2]

Recently ive seen a few melted moulded plugs though, ... I would have thought moulded plugs were all made standard to take a maximum of at least 13 amp, even the ones on 10amp leads, surely they wouldnt rate some moulded plugs at 10 amp max would they.

I would have thought that, too, and I'm not sure what one would do to the design to cause them to melt at currents >10A!

What sort f current has been responsible for the melted plugs you have seen?

Kind Regards, John

 

[333rocky333]

The rating plates are usually missing or worn away on the equipment, as there in commercial kitchens but they tend to push the plug limit and come supplied with a moulded 13 amp plug.
A recent case was the manufacturer said the 13 amp fuse was too small and overheating and said cut it off and fit a 16 amp blue plug and socket, even though it was supplied with a uk moulded 13 amp plug/
However one melted on a hoover and theres been a few reports on here of 3kw heaters doing similar
I often wonder how they terminate the wire to the pin internally

Sorry for hijacking the thread eveares

 

[ban-all-sheds]

for example the kettle lead is rated 10A.

Why is this when the cable is often 1.5

The C13/C14 connectors are only rated for 10A.

If the load is ≤10A and the nature of the load is such that it is "unlikley to create an overload" (i.e. result in a current >10A, other than true, very high, 'fault' currents), I would not have thought that would be a requirement to have a 10A fuse, even if the connectors were only rated at 10A, provided the fuse fitted (e.g. 13A) was adequate to protect the cable (which it would be for any flex ≥1.25mm²), would there?

The C13/C14 connectors are only rated for 10A..

Thanks thats the only reason I could see. Seems odd to me why they are though.

As I've just written, I'm far from convinced that that, per se, is a reason for needing a 10A fuse. I also agree that it seems very odd/unlikley that they can't 'cope' with at least 13A!

You're all missing the point.

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.

And the standard requires that it only be capable of carrying 10A. Since these leads will legitimately be sold to literally (original meaning, not the recently approved hey-lets-give-in-to-the-ignorami-once-more one ) hundreds of millions of people who have no fuses in their plugs and who will legitimately use them on circuits protected by 16A breakers, there cannot be a requirement for them to be fused at 10A.

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. Who have no idea what their product will be used for when they make it - all they know is 230V±, 10A max, 70°C max conductor/contact temperature.

The move away from the use of "kettle connectors" for kettles to the use of powered bases on which they sit hasn't just had ease-of-use benefits - my kettle draws 12A (at U0 ), so it boils faster, and thus wastes less power, than one limited to 10A.

 

[ericmark]

I'm thinking that it might help the OP to explain how a fuse works.

I was reading the explanation and it struck me how different the inside of a fuse is. I remember opening a bottle fuse 25A and a 16A and swapping the foils as the 25A would not fit the holder and the freezer had a motor using 20A.

It is unusual to open a good sand filled fuse normally one only ever sees a blown fuse when it falls apart.

The foil had in the centre a series of holes so the part which would rupture was far smaller cross sectional area than the rest of the foil. This is some times seen with glass fuses where there is a necking of the fuse in the centre.

This reduced cross sectional area in the centre also reduces the heat the fuse casing reaches.

the pictures show some of the fuses where you can see what is inside. Materials also differ from lead to silver to copper all used in fuses.

The design of the fuse not only alters the graph as to how much current for how long makes it blow but also the heat radiated from the fuse.