Charlie Shiels elements or Argos kettle?

[LordEoin]

Surely that'd be the plug, not the lead

[JD]

You need proper kettle leads to stop them melting as far as I know

Almost true. Melting leads is not the problem but just a step on the way to the real problem.

Firstly, the word "lead" means the cable and plug. The plug is the means by which the cable is connected to the element and represents the last inch or less. Both cable and plug are equally affected by the conditions that apply when talking about "kettle" leads or "computer" leads.

Kettle leads are electrically the same as computer leads. Physically, they differ in that they have a little slot on one side that matches up with a little projection on the kettle socket. This slot is there to prevent computer type leads from being used where kettle type leads are required. Materially, they are very different.

First thing to know is that the flow of electrical current generates heat. If you use a computer lead and a kettle lead that are rated to carry the same current, then both these leads will be able to easily deal with THAT heat.
If both kettle leads and computer leads can carry the same current so why are they different? The issue here is not so much heat as temperature. Kettle leads are made of a material that  can tolerate high temperatures whereas computer leads are not so hi-spec. Why is this important?

Computers and their like, will typically not produce such concentrated heat as a kettle. The current they consume is used to do other work. This work takes energy and leaves a lot less energy that can produce heat. Any heat that is generated will not be generated that close to the lead and will typically be dealt with using some sort of cooling system. The result is that with computers, the cable will not be subject to that much heat over an above that generated by the passage of current alone.

Kettle elements are designed to use all the electrical energy in producing heat. This means the bit of the elements touching the water reaches 100^oC. The inner core of the element will be hotter again. The lead will be connected to the inner core and will be very close by. Significant heat will be conducted along the element to the lead. The lead will therefore be subject to more heat that that caused by the passage of current alone. Over the course of a typical kettle boil, in a normal kitchen environment, the leads will not be stressed too much and both types of leads will likely work fine. If, however, the lead can't cool itself, because the kettle is used too much and/or because the air around it is too hot, the lead will be stressed. In this scenario, a computer lead will soften and may even start to melt. Melting would be a problem in itself because it can lead to a short. A short is dangerous but will often be protected by your circuit breakers. Melting plastics, however, give off volatile gases and these can ignite. And this ignition will not cause a breaker to trip until the flames start to carbonise the case around it. At this point, the fire could easily be beyond control and your breakers tripping won't help you.

In a brewing scenario, we boil for an hour or more. This means the kettle element is being used for more that the typical 5 minutes it take to make a cuppa. Even kettle leads will be used beyond their expected use by this. This means that the risk of a problem is always higher. If you brew outside, you'll probably get away with it because the cooling of the ambient air will keep everything within tolerances. Even if you don't get away with it, the damage an outside fire can do will likely be contained. Indoors, I'm strongly recommending people use the proper leads. I can be wrong about this a million times and there will be no significant consequence. If you use the wrong leads, you can't even afford to be wrong once.

The proper leads are not that dear. Use the proper leads.
/J

[LordEoin]

rightio. I'll bow to witchcraft and magnets. better safe than sorry.

[Sorcerers Apprentice]

The confusion is between a C13 computer connector and a C15 kettle connector, the C15 is rated for 120c while the computer type C13 is only rated at 70c . The C 15 has a slot removed as JD has said already. Take a look at the link below.
http://en.m.wikipedia.org/wiki/IEC_60320
There are charts explaining the differences in the appliance coupler standard sheets
I imagine Charlie Shiels must sell these along with most electrical wholesalers

[LordEoin]

Ok, so it's all down to how hot the kettle end connector can safely get. Cool cool. will be replaced by next use 

[johnrm]

I just checked a random but standard computer cable.
The Cable is made up of 3 x .75mm sq
Googling tells me .75mm is good for 6A
Note also that the plugs on these are usually stamped with 5A and use 5A Fuses.
While we CAN shove in 13A, this is dangerous

Pop into Maplin...
IEC C15 10A Rating...
http://www.maplin.co.uk/p/maplin-10a-hot-condition-euro-line-socket-n08kc

Rough Service mains plug... (Oh all right, Giggity)
http://www.maplin.co.uk/p/13a-rough-service-mains-plug-black-nh65v

1mmsq can handle 10A
http://www.diy.com/nav/fix/electrical/electrical-cable/flexible_cable/Tower-Flex-Rubber-3-Core-DR103L25-Black-1mm-x-25m-9290536

1.5mmsq can handle 16A
http://www.diy.com/nav/fix/electrical/electrical-cable/flexible_cable/-colourderived%3Eblack/Tower-Flex-3-Core-D153BLL25-Black-1-5mm-x-25m-9290532

The Math is easy if you look at these numbers...
2200W / 220v = 10A
Or if you're lazy...
http://www.supercircuits.com/resources/tools/volts-watts-amps-converter

Useful explanation of stuff here...
http://kevinboone.net/cableselection_web.html

[LordEoin]

Wow, I've gone overboard so with my new 2.0mm sq wiring. Ah well... to be sure, to be sure! 

[LordEoin]

I bought a kettle lead in an electrical shop and it has  a 13 amp plug, .75mm lead, 10amp C13 (no notch) connector.