TOT: current carrying capacity of 0.75mm csa wire
wrights...@f2s.com
strand 0.75mm csa insulated wire get hot enough to burn nearby timber.
Not enough current to make it melt; just enough to get it very hot.
The wire in question was one conductor in a three core mains flex.
Ambient temperature was about 15C.
Bill
John Rumm
It will depend on how its mounted... in contact with a non insulating
building material like plaster etc will get its highest rating. Hanging
in free space will be a bit less, and buried in something insulating,
then much less.
0.75mm^2 is nominally rated at 6A. However I expect that is quite
conservative, and is probably not computed using the same 70 degree C
temperature budged allowed for flat solid core mains wiring cable[1]. I
would expect that it would carry 10A - 12A or so long term. That would
get it to 70+ probably but a tad less than the melting point of the
insulation.
[1] That being the maximum operating temperature that will still yield a
useful service life. The smallest house wiring cable is 1.0mm^2, which
in the most favourable conditions will carry 16A continuously without
damage at maximum operating temperature.
--
Cheers,
John.
/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
MartinR
wrote:
I once saw a 4 mm^2 equipment wire strung from a control panel to a
machine as a temporary measure, create a curtain of smoke as the
insulation disintegrated, followed by quite a nice pattern of red
heat, followed by a severance of the wire. It had got trapped in a
door on the machine and shorted to earth. Somehow someone had
forgotten to insert a fuse or circuit breaker and the 120A cabinet
isolator was not sufficient to prevent quite an exciting event.
Chris J Dixon
>I once saw a 4 mm^2 equipment wire strung from a control panel to a
>machine as a temporary measure, create a curtain of smoke as the
>insulation disintegrated, followed by quite a nice pattern of red
>heat, followed by a severance of the wire.
I have seen a similar effect with a much smaller wire, and the
smoke curtain, which followed the contours of the wire, was
remarkable, though the ensuing complete vaporisation of the wire
was pretty swift.
Chris
--
Chris J Dixon Nottingham UK
ch...@cdixon.me.uk
Have dancing shoes, will ceilidh.
wrights...@f2s.com
Thank you John.
Bill
bin me
<ch...@cdixon.me.uk> writes
>MartinR wrote:
>
>>I once saw a 4 mm^2 equipment wire strung from a control panel to a
>>machine as a temporary measure, create a curtain of smoke as the
>>insulation disintegrated, followed by quite a nice pattern of red
>>heat, followed by a severance of the wire.
>
>I have seen a similar effect with a much smaller wire, and the
>smoke curtain, which followed the contours of the wire, was
>remarkable, though the ensuing complete vaporisation of the wire
>was pretty swift.
>
>Chris
off for hours per day to preserve coal supplies. Our kit was battery
operated (very very large lead/acid batteries) so decided to install a
temporary battery charger for when the mains power was on to augment the
existing charger, to "help keep the batteries fully charged". Having
used the correct box spanner to loosen the terminals on the existing
charger output, one nut became stiff on its post bolt. I reached for my
hardy half-round nose pliers, but momentarily touched the other terminal
with them. This put a full short over the battery, not even a fuse in
the way to save the day. It wasn't the crack as contact was made, nor
the flame of the burning arc or the smoke, but the smell of vaporised
metal pliers certainly had me heading for the nearest toilet!
--
Alan