And the moral of this story.......
shortie - 29/1/05 at 05:15 PM
Make sure you unwind your extension lead before you plug in your 1KW heater!!! 
http://www.locostbuilders.co.uk/upload/Extension_Lead_01.jpg
http://www.locostbuilders.co.uk/upload/Extension_Lead_02.jpg
Seriously though guys I didn't even think about it and fortunately I have a circuit breaker fitted which tripped the power out.
When fully unwound it can handle something like 4000W but if you leave it wound on the reel it can only handle 720KW, given that the heater was 1KW it
fried!! Could have been much more serious.
Worth mentioning so that others know, I knew it but didn't even think about it when I plugged it in.
Rich.
[Edited on 29/1/05 by shortie]
scotlad - 29/1/05 at 06:04 PM
oops
Northy - 29/1/05 at 06:10 PM
I don't think "a bit of tape" will fix that one!
Peteff - 29/1/05 at 06:14 PM
How far was the heater from the socket if you didn't need to unroll the extension?
Ben_Copeland - 29/1/05 at 06:14 PM
Health and Safety states that you should unwind all reel cables anyway 
and take the knots out of cables too.
Lucky you had a trip switch
Northy - 29/1/05 at 06:15 PM
quote:
Originally posted by Ben_Copeland
Health and Safety states that you should unwind all reel cables anyway
Trip hazard! 
Ben_Copeland - 29/1/05 at 06:21 PM
Thats what i thought... but it's better than setting fire to ya place!
Northy - 29/1/05 at 06:22 PM
They'll shut ya down anyway the ba***rds!
shortie - 29/1/05 at 06:28 PM
Heater was about 3 metres away but there was still loads on the reel, not sure I needed the heater anyway as the cable provided a fair amount of
heat!!!!
CairB - 29/1/05 at 06:29 PM
quote:
....but if you leave it wound on the reel it can only handle 720KW, ...
720KW.. thats some extension lead
shortie - 29/1/05 at 06:31 PM
Oh yeah, should have said when wound on the reel it takes 720W not KW!
chunkielad - 29/1/05 at 07:45 PM
It's mad when those magnetic forces create heat and fry electrical components!!!
Oh and to stop the trip hazard with fully unwound reels, you need to use cable bridging (the rubber ramp stuff that goes over the cable run).
CairB - 30/1/05 at 10:21 AM
Just an observation...
I think that the phenomenon is mainly due to the fact that the current capacity of the cable is based on it's ability to keep the temperature of
the insulation down to an acceptable level. The rating will be based upon the cable being in free air at moderate ambient temperature. The current
capacity is derated when cables are grouped together or not in free air conditions or higher ambient temperature.
These factors also affect the rating and type of the circuit breaker / fuse due to the temperature rise that occurs due to the let through energy as
the device is tripping.
When cables are on a reel there is a double effect, one due to the extra insulation and the insulation is a heat source due to resistive heating.
The magnetic affect can be interesting though. I once had a screwdriver shot out from the centre of a coil when passing current. I'd left it in
the centre of the coil so that I wouldn't loose it.
Cheers,
Colin
NS Dev - 30/1/05 at 11:00 AM
We recently had to run an "extension lead" to one of the main drive motors at work, as the cabling/busbars had failed in a wiring duct.
The motor in question pulls 7000 amps and is a little over 1500KW (2000hp approx) and the size of a transit
van..........................................glad we didn't leave that lead rolled up!!!!
ned - 31/1/05 at 09:56 AM
my dad managed tha once, think it was with a welder with the extension lead still reeled up..
Ned.
Peteff - 31/1/05 at 11:27 AM
Not quite that large but we helped the sparkies to fit a machine at work once and it took 8 of us to drag the cable into place. Sounds like what you
need Shortie. You'd have to be blind to trip over it as well.
dern - 31/1/05 at 11:53 AM
quote:
Originally posted by CairBThe magnetic affect can be interesting though. I once had a screwdriver shot out from the centre of a coil
when passing current. I'd left it in the centre of the coil so that I wouldn't loose it.
I know your intent was to warn but I just
have to try that
Mark
James - 31/1/05 at 04:44 PM
quote:
Originally posted by dern
quote:
Originally posted by CairBThe magnetic affect can be interesting though. I once had a screwdriver shot out from the centre of a coil
when passing current. I'd left it in the centre of the coil so that I wouldn't loose it.
I know your intent was to warn but I just
have to try that
Mark
Isn't it know as a Rail Gun?
James