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I want to build a quick cheap heating pad using a non-coated electric wire (such as Nichrome, or Kanthal).

Would a high temperature resistant electrical tape could work as an electric insulator? (It would prevent shortcircuits from moisture)

The tape (or any other material suggestion) must of course let the heat pass through.

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  • \$\begingroup\$ Why don't you use the element from a kettle? \$\endgroup\$ – Andy aka Sep 30 '15 at 8:56
  • \$\begingroup\$ @Andyaka I only want to warm my bed not burn it, but that would be also quite interesting to sleep on such hard piece of metal ;-) \$\endgroup\$ – JinSnow Sep 30 '15 at 9:03
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    \$\begingroup\$ Our little conversation should inform you that your question will probably raise more questions than answers initially so, you should try and be as complete as you can and justify why you are unable to buy an electric blanket. \$\endgroup\$ – Andy aka Sep 30 '15 at 9:09
  • \$\begingroup\$ Buy a heating wire with shield. Connect the shield to earth and use ground fault disconnector for two terminals. Or you plan to kill somemoene? \$\endgroup\$ – Marko Buršič Sep 30 '15 at 9:46
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Kapton tape is good up to 400C. However it's not great when subject to wear (wikipedia):

Kapton insulation ages poorly: an FAA study shows degradation in under 100 hours in a hot, humid environment.[6] It was found to have very poor resistance to mechanical wear, mainly abrasion within cable harnesses due to aircraft movement. Many aircraft models have had to undergo extensive rewiring modifications--sometimes completely replacing all the Kapton-insulated wiring--because of short circuits caused by the faulty insulation. Kapton-wire degradation and chafing due to vibration and heat has been implicated in multiple crashes of both fixed wing and rotary wing aircraft, with loss of life

And of course connecting a homemade electric blanket to the mains whose insulation may wear out is a good way to accidentally kill yourself in your sleep.

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  • \$\begingroup\$ +1 for, "good way to accidentally kill yourself in your sleep." \$\endgroup\$ – Chuck Sep 30 '15 at 11:27
  • \$\begingroup\$ @pjc50 it will be powered by an AC computer charger (19V/ 3 A), thanks for your answer! \$\endgroup\$ – JinSnow Oct 1 '15 at 8:01
  • \$\begingroup\$ At 19V your insulation demands are much less critical. If designed for 2A operating current with a 2.5A fuse you almost have a safe situation. There is available insulated heating wire that would possibly solve your problem with the least fuss. \$\endgroup\$ – KalleMP Mar 10 '16 at 20:32
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Have you looked into heatshrink? They can withstand the heat, but it might not be the most cost effective solution depending on the length of the wire.

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  • \$\begingroup\$ I'm pretty sure that for the cost of several meters of heatshrink, you could buy a cheap electric blanket... \$\endgroup\$ – Someone Somewhere Jun 4 '16 at 11:25

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