Forgetting for a moment that wires can get hot, and that electrical tape can melt because of it: I've been wondering how much voltage/amperage it would take to spark through your standard house hold electrical tape. While the electrical tape is an insulator, nothing is a perfect insulator, right? It's just a matter of resistance, isn't it?
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\$\begingroup\$ When in school, I heard 3M electrical tape insulates to 1,000v per mil. That's much better than air. \$\endgroup\$– OptionpartyCommented Jan 16, 2015 at 0:26
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\$\begingroup\$ As a general rule, electrical wiring materials intended for household use are good to at least 600V. (Some industrial stuff, of course, is rated much higher.) \$\endgroup\$– Hot LicksCommented Jan 16, 2015 at 1:00
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\$\begingroup\$ And it's not a matter of resistance, usually, but rather (as mentioned below) "breakdown voltage" -- the voltage at which the electric field is strong enough to essentially disassemble the material. \$\endgroup\$– Hot LicksCommented Jan 16, 2015 at 1:03
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1\$\begingroup\$ (Some high-voltage insulators are actually built using materials that intentionally have a lower than possible resistance, so that the electric field will be uniformly distributed along the insulator rather than possibly building up in one place.) \$\endgroup\$– Hot LicksCommented Jan 16, 2015 at 1:06
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1\$\begingroup\$ In any case think about that the electrical tape it is not like the original cable insulator. See carefully if the temperatur rating characteristics of tape is for the material (PVC e.t.c) or to the glue. Many times glue melting in lower temperatures than the manufacturer states. \$\endgroup\$– GR TechCommented Jan 16, 2015 at 5:08
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1 Answer
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You're looking for the dielectric breakdown voltage of electrical tape. For this 3M brand it's 10kV.
So, if you get to about 10,000 volts, it'll spark through. For the equivalent thickness of air (0.216mm) it would only take 648 volts to spark.
Once it's been sparked through once, the insulating properties for that spot are probably greatly reduced. It'd require much less to spark through the same spot again.
The resistance is another matter. It's rated at 1e6 megohms, so some very very small current will flow at any voltage.
