In sci.engr.lighting Franc Zabkar wrote:
On Thu, 08 Dec 2005 02:22:25 GMT, JS
put finger to keyboard and composed:

On Wed 07 Dec 2005 18:24:48, Victor Roberts
wrote:

But you must never use the cable whilst tightly coiled up
(unless you have deliberately overspecified its capacity). A
coiled cable has a much higher AC impedance due to induction and
can overheat alarmingly.
snip
I have often wondered about how much of an effect my very neat
coils of mains flexes for my PC was having! And I really do seem
to have a lot of devices which plug into the mains.

What about the magentic or ERF effects of a tightly coiled main
flex? Say, 12 neat-ish turns with a diameter of 5 or 6 inches
.... How much of a nuisance might such a thing be to electronic
equipment like my PC?

The magnetic field produced by any number of turns of mains flex is
zero. Think about it.

For differential mode current only.
For common mode signals, like RFI on all three wires, probably not.