Paul, No I didn't find it nec to 'encase the 2 turns' but you could, as this would keep the heat in a little better. Poss. use 'Glass' tape with a layer of 'ripstop' gaffer tape over it.
Geoff, Thanks for comments. Actually you only need around 300 mm, max of 350. This was found by practical use, outdoors. Anything longer was pretty useless, heat wise. I couldn't feel any heat in my hand/fingers at all. You just need to measure 300 mm + 10 mm for terminating each end. No DMM req'd.
HTH.
L.
see link;
http://www.iceinspace.com.au/forum/s...ead.php?t=1640