Typically it's PVC and a low grade at that, and now it goes stiff in
cold weather, and it's starting to fray & split at the connection
What kind of clamp are you using at the box? I find that the kind where
two screws clamp a curved metal plate onto another curved metal plate
sort of works if you don't move the cable much. The kind where a metal
nut forces a rubber bushing around the cord has worked better for me.
You can also get this kind with a braided steel cable "finger trap"
trailing from the nut, to provide additional strain relief; the "finger
trap" goes around the cable and gets tighter as the cable is pulled.
This kind is often used where the cable has to support some weight, like
an operator control box that hangs from the cable. (These clamps are
as seen in the US; your country may vary.)
Is there any super-flexible cable, even if expensive, that will stay
that way even in cold weather, and is abrasive-resistant too?
In the US, "SJO" cable (Service, Junior, Oil-resistant outer jacket)
might fit this application. The outer jacket is typically black
neoprene rubber. A couple of web sites tell me that this has now been
superseded by "SJOOW" cable (Service, Junior, Oil-resistant outer
jacket, Oil-resistant conductor insulation, Weather resistant). Both
types are available in a variety of conductor counts and sizes from
around 18 AWG to 10 AWG, or roughly 7 A to 30 A at 120 V. The local
hardware store will sell me a 30 meter roll of 14 AWG 4-conductor SJOOW
Just going by the pictures, the H07RNF cable that Andrew linked to
looks like a UK equivalent of SJO/SJOOW.
I also have a standard household type extension cord that is made to be
flexible in cold weather. By comparison with cheaper PVC cords I have,
it *is* easier to handle, at least down to around 0 F (-18 C). Among
the markings stamped on its jacket are "SJTW FT-2 (-50C) (-58F) COLD
FLEX". It was made by Woods, which is now part of Coleman Cable.
If you're not in the US, maybe go to the local theatre, exhibition hall,
or concert venue, and ask where they get their stage power cables. Then
get in touch with that vendor and tell them what you need, including if
you need to use it outdoors - they will probably know the right cable
and be able to supply it. (Stage cables have to do the same job that
you seem to want to do: reasonable amounts of power, and get coiled up
and uncoiled all the time.)
Your friendly local airplane shop will have PTFE (Teflon) insulated
wires in various sizes, but I'm not sure if they have them as multi-wire
cables or not. One online shop sells PTFE wire in 10 AWG - 7.6 meters
for US$92. That's a single conductor; multiply by four for your