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In Reply to: This is how I look at it. posted by cheap-Jack on March 27, 2007 at 08:25:44:
DCC (Double cotton covered) copper wire was all there was in the days before varnishing and plastic extrusion.I have some interesting old radio books showing how to wind 500V coils with DCC wire. ETC.
You may do what you wish, of course, but it doesn't help others to make questionable claims, and your 1 ohm figure is nonsense!
Follow Ups:
Hi.In the good old days, before the National Board of Fire Underwriters
(NBFU), UL & CSA stepped in with the electrical standards, you could use whatever you wanted. Who would give a damn?But if you use anything electrical, not rated by UL or NBFU or CSA (in Canada) today, you are asking for trouble in case of fire.
The answer is a value in ohms, perhaps with a explanation of measurement method.My example of how cotton WAS used simply illustrates that it cannot have a inherent low resistance.
Your lecture on fire hazards etc is not releavant and just a diversion.
Your lecture on fire hazards etc is not releavant and just a diversion.
Yup. He originally said "Its resistivity is 1,000R/cm, or 1 ohm per mm. Theoretically, it can't handle any voltage at all !!!!" Now he's just doing a lot of dancing around. Not worth the time.
se
Hi.Basing on 1,000,000,000R/cm3, I deduce electrical resistance per linear mm is 100R (cube root of the above figure).
You said I was wrong. So what is the correct insulation resistance per mm thickness of cotton ???
Basing on 1,000,000,000R/cm3, I deduce electrical resistance per linear mm is 100R (cube root of the above figure).
Uh, 100 is the cube root of 1,000,000,000? I think you need new batteries for your calculator.
se
Hi.My calculation based on cotton's 100 million ohms/cm3 is 100R/mm.
You said it was "nonsense".Now you come up with less than half of my calculated value, only 42R.
So your's a "Double Nonsense".I got the impression neither of both insulation resistance numbers is correct.
Insulation resistance is in the range of mega ohms. Under a test voltage 250VDC, min. insulation resistance is 250KR. For 500VDC, 500KR, & for 1KV, 1MegaR. If a cotton wire could handle up to 500VDC,
its insulation resistance got to be in maga ohm range.So how you arrived this lowly 42R?
c-J
So how you arrived this lowly 42R?
I didn't. Deep Thought did. And it's not 42R, it's simply, forty-two.
se
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