Melting point of silicone cable insulation?

I am in the UK.
What is the temperature of the melting point of insulation on mains flex which is made of silicone?
Does anyone have a comparable figure for PVC insulation?

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The rated cable temperatures for each (slightly below the actual melting/charing point), for typical versions are: PVC 105C Sil 180C Teflon 260C Glass 400C
The last is the most variable, with different types of glass insulation, pushing this up to over 700C. You also get glass loaded silicone, typically rated to about 200C. Silicone rubber, doesn't melt, it sort of 'chars'. All of these are 'continuous' ratings.
Best Wishes
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On Tue 10 May 2005 16:41:54, Roger Hamlett wrote:

Does anyone know how much temperature the mains leads with a woven cotton outer can withstand?
Is a woven cotton outer better or worse than silicone insulation?
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The cable is silicone. Nowadays, the woven cotten is just retained to stop it snagging on the cloths you are ironing, so the cable easily slides over the cloths and the edge of the iorning board.
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Andrew Gabriel

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Andrew Gabriel wrote:

Oh, is that what it is for? Thanks, I had wondered.
My thought had been that it was there to fray and generally become a mess quite quickly - so the owner had to go out and buy a new iron...
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Sue

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With me, it's normally some part inside the iron which fails before the cord. Actually, I have a couple of cords I cut off irons when the rust was being chucked out.
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On Sat 14 May 2005 15:20:36, Andrew Gabriel wrote: < writes:

I thought a side benefit of the cotton covering was that it did not kink so easily. Mind you, when it does kink then it really does kink.
However I figured from a "side comment" which I read in an electrical catalogue that the cotton probably had good heat-resistent properties too. I just don't know how the heat-resistent property might be quanitified.
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If you go back to days of old rubber insulation, cotten was used on any appliance which got hot, such as toasters, heaters, etc to help protect the old rubber which would burn. I think it's only still used on irons nowadays as the solicone insulation doesn't require any additional heat protection, but has a rather high friction coefficient with fabrics.
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Andrew Gabriel

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On Tue, 10 May 2005 16:21:28 +0100, the renowned Lars

You're premise is wrong. Silicone insulation doesn't melt- it chars. Operating temperature ratings are typically around 200-250C, IIRC.

Ratings typically run from around 80C to a bit over 100C. Burning moderate quantities PVC can be hazardous.
Best regards, Spehro Pefhany
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On Tue, 10 May 2005 11:50:45 -0400, Spehro Pefhany

^^^^^ As is the above apostrophe ;-)
Best regards, Spehro Pefhany
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Spehro Pefhany wrote:

Visiting too many premises has that effect on me too...
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Actually, visiting just one will do the job, I dissolve in
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The immersion heater cable you can buy is, I believe, 180C max operating temperature, but it's rubber (and I don't think silicone). I'm not sure these have a 'melting' point, as the rubber is thermosetting insulation, which will probably jusy go hard, and eventually char or burn.

There are different types of PVC. The Twin and earth normally used for wiring is derated to zero current at 70C ambiant, or designed to operate at 70C at max current (whichever way you want to look at it). IIRC, this allows for fault currents to raise the temperature another 90C to 160C (in the time it takes the protective device to trip), which is regarded as the max momentary conductor temperature allowed before the cable sustains instant permanent damage. So I presume it's above 160C but cable is not designed to operate that hot other than in occasional fault conditions.
Temperature affects the life in years of wiring too. At 70C, you can expect PVC wiring to last around 23 years, whereas at 40C the life is (calculated) at 1,498 years. See: http://www.iee.org/Publish/WireRegs/Commentary-UpdateApr04.pdf
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Two stories from ages ago... (60s)
My father was OEM sales manager for Pass and Seymour. They used to make things like big ceramic sockets for street lights. Some of his customers wanted high temperature pig tail wires on those sockets. For silicon rubber, the limit was not the insulation. The copper wire (fine strands) inside corroded too fast at temperatures which were fine for the insulation.
I spent a summer/co-op at GE's Engineering Standards Lab. They used to test parts coming in from vendors. Standard procedure was to give a sample part and the spec to a technician. Technician would read the specs and do all the the tests. My boss told me the story of a spec that (essintially) called for silicon rubber on flexible waveguide. Spec said roughly: bake at x C for 1 hour. No problems sould be visble on the furface of the insulation. x was big.
The technician turned on the oven, cut a couple of lengths of heavy wire off the spool, bent them into hooks and suspended the sample (2 ft long?) from the screw holes in the end bells to the rack in the oven. Then he set the timer for an hour and went to lunch. A short time later there was smoke all over the place. The solder holding the end bells on had melted. (I said x was big.) The silicon rubber had fallen on to the way-hot floor. Other than a bit of scorching where it had hit the floor, the insulation was fine.
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