Oh Dear! Spotted at St Mabyn Cornwall
- Thread starter Dustydog
- Start date
- Mar 8, 2009
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See it many times on site, many still wrapped tightly on drums!. Used to try and 'broach' the subject to the users, many looked at you disbelievingly, and ignored it. Haven't bothered now for a few years, just makes you wonder what other 'suspect' practices they have particularly when you watch them unload everything from the floor of the van.
- Nov 16, 2015
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Yes , They are sharp kinks, look at the colour of the cable,
For the Newbies, if you keep cable rolled up like that then it will create a heat build up and a potentiale fire, also your compass on your bike will keep taking you back to the caravan and not to the pub, you were looking at on the map.
For the Newbies, if you keep cable rolled up like that then it will create a heat build up and a potentiale fire, also your compass on your bike will keep taking you back to the caravan and not to the pub, you were looking at on the map.
- May 7, 2012
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You see the tightly wrapped cables on most sites. Their is a slight fire risk but in general it is unlikely you will have the level of power going through for long enough for this to happen. Those sharp kinks are potentially a real problem though as it could split the insulation and leave live wires exposed or fuse the electrics.
- Jul 15, 2008
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.........I agree with Ray in that a coiled up purposed designed EHU cable carries very little risk as compared to an uncoiled one.
Purpose designed EHU cables are designed to carry 16 amps and the supply bollard will have an overload MCB which will trip at a value at or below 16amps.
There is a fire risk when non standard EHU cables are used which are rated below 16 amps and left coiled in use.
The is also a fire risk when any supplementary coiled extension cable is used anywhere that is overloaded by the appliance that is powered from it.
Sprocket's link points to a fire caused by a supplementary coiled extension cable being overloaded in an awning.
The caravan's fire alarm had had the battery removed.
Purpose designed EHU cables are designed to carry 16 amps and the supply bollard will have an overload MCB which will trip at a value at or below 16amps.
There is a fire risk when non standard EHU cables are used which are rated below 16 amps and left coiled in use.
The is also a fire risk when any supplementary coiled extension cable is used anywhere that is overloaded by the appliance that is powered from it.
Sprocket's link points to a fire caused by a supplementary coiled extension cable being overloaded in an awning.
The caravan's fire alarm had had the battery removed.
- Mar 8, 2009
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- Jul 15, 2008
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No.......it is normally uncoiled.
I have more than once left my EHU cable coiled in snow conditions when it has been snowed on.......the snow did not melt even though a full 16 amps was being used to keep warm inside the caravan.
On the other hand I once found Belinda Using a 1.5 kilowatt iron whilst plugged into a 1 kilowatt rated coiled extension lead at home and was mortified!
Soon put a stop to that!
BTW........ that 1 kilowatt coiled extension lead had 3 sockets so it had the potential to plug in 3 appliances at the same time!!
I have more than once left my EHU cable coiled in snow conditions when it has been snowed on.......the snow did not melt even though a full 16 amps was being used to keep warm inside the caravan.
On the other hand I once found Belinda Using a 1.5 kilowatt iron whilst plugged into a 1 kilowatt rated coiled extension lead at home and was mortified!
Soon put a stop to that!
BTW........ that 1 kilowatt coiled extension lead had 3 sockets so it had the potential to plug in 3 appliances at the same time!!
- Jul 22, 2014
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Gafferbill said:
A mains extension lead "rated at 1 kW" should have had a 3A fuse in the plug. Then the fuse would blow at about 3/4 kW. It would not matter safety-wise how many downstream appliances were plugged in; such safety should not depend on the end user.
FWIW, leads are not rated in kW (except possibly by non-technical marketing people), they are rated in amps. The Wattage they are transmitting is the amps times the voltage of the supply. If a lead were to melt transmitting 1kW if that were due to 230 volts times 4.3 amps, then it would also melt at a piffling 52 Watts if that were at 12 volts times the same 4.3 amps. It could however carry a respectable 50 kW if the voltage were 11,000v, which is why electrical transmission lines run at high voltages. Above 11,000v however you are into cable separation and glass insulators.
- Jul 15, 2008
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.......for the record.
The extension lead my wife was using is coiled in a plastic case, extends to 7 meters and the plug is fitted with a 5 amp fuse. It is rated at 0.6 amps and is fitted with a thermal cut out.
The casing is stamped with a warning......................
Maximum of 1 kilowatt cable fully coiled.
Maximum of 1.5 kilowatt cable fully extended.
The reason I was mortified with my wife's use of a 1.5 kilowatt iron was that she was using it coiled to provide a 1 meter extension.
The extension lead my wife was using is coiled in a plastic case, extends to 7 meters and the plug is fitted with a 5 amp fuse. It is rated at 0.6 amps and is fitted with a thermal cut out.
The casing is stamped with a warning......................
Maximum of 1 kilowatt cable fully coiled.
Maximum of 1.5 kilowatt cable fully extended.
The reason I was mortified with my wife's use of a 1.5 kilowatt iron was that she was using it coiled to provide a 1 meter extension.
I agree with Gaffer. The way that lead is coiled presents very little, if any risk. Problems occur when the lead is tightly wrapped around a drum,not coiled loosely by hand.And you would need to be using something like an immersion heater and kettle and toaster etc for a long period all at the same time, which would be impossible on a campsite.
Not that I'm condoning what is shown, but let's keep it in perspective.
Not that I'm condoning what is shown, but let's keep it in perspective.
- Nov 16, 2015
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Coiled power cables are always dangerous. ,
I put i a purchase order for the company, for a specific power cable, logistics accountants, changed these for cheaper items, labled as from Ireland, (lovelyPlace). Turned out Chinese fake, and almost burnt down the Aircraft hanger through not being unwinded from the drum.
I put i a purchase order for the company, for a specific power cable, logistics accountants, changed these for cheaper items, labled as from Ireland, (lovelyPlace). Turned out Chinese fake, and almost burnt down the Aircraft hanger through not being unwinded from the drum.
- Mar 14, 2005
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There are three main causes for heat build up in a coil of wire carrying an AC current. The first is the heating effect of the current passing acting on the ever present resistance in a conductor. The second is the the effect of the power factor of AC appliances, and the Third is the induction effect, which is usually related to high frequency electrical systems.
The induction effects are miniscule at normal mains frequency so for this purpose can be ignored.
The Power factor is consideration where there are large electric motors and a lot of old style fluorescent lighting more of an industrial problem than a caravan, so again this can effectively be ignored in this instance.
As most caravans present a majority resistive load, we can use simple Ohms law heating calculations.
Every electrical cable has some resistance. Resistance opposes the passage of a current, and in doing so the lost current is released as heat. The standard EHU cable has conductors of 2.5csa will have a resistive value of about 0.007Ohms per meter for each conductor.
From:
http://www.nktcables.com/dk/products/railway/railway/technical-information/~/media/Files/NktCables/Products/UK/Railway/technical%20info/Copper-wire-table.ashx
Because the same current flows in both Live and Neutral conductors you have to double the value to 0.014Ohm per meter of EHU cable. The earth conductor should not have any current flowing, so it will not produce heat.
As we are have Current and resistance, Ohms law tells the energy (heat) is the calculated by the Current squared times the resistance. If the cable was carrying its full rated current of 16A then we would get heat losses of 16A x 16A x 0.014Ohms = 3.584Watts per Meter
For a full 25M EHU that would be 89.6W. Do you remember how hot a 40W light bulb got well this is two and a bit light bulbs of heat. If this was tightly coiled you can imagine how hot it can get. But that is if it is carrying the full 16A, which most of the time it won't be.
The kinks in a cable can start to produce problems if the conductors have been constantly stressed they can start to stretch and loose csa which raises the resistance at that point. This can lead to a hot spot in the cable as well as the damage to the insulation mentioned by others.
The standard EHU cable uses PVC on PVC insulation and will be rated for a maximum surface temperature of 70C. BUT If a cable self heats and is produces 70C surface surface temperature, it must be significantly hotter inside, and that will be enough to deform the insulation and reduce its effectiveness, rendering dangers of electric shock as the insulation may have thinned.
I would prefer to see the coil in the picture spread out a bit more so it is better able to lose heat more effectively. The kinks should also be avoided to prolong the life of the EHU.
The advice about uncoiling cables is principally aimed at cables that are tightly coiled on a drum or more particularly in an enclosed drum, where there is little means to let the heat escape which can cause a temperature build up. This can start a cascade reaction because as copper heats up its resistance increases, which means for any given current more energy will be lost in the cable generating even more heat. The corollary of this is as the resistance rises less current will pass for a given supply voltage, but that is not an excuse to leave power cables tightly coiled when in use.
The induction effects are miniscule at normal mains frequency so for this purpose can be ignored.
The Power factor is consideration where there are large electric motors and a lot of old style fluorescent lighting more of an industrial problem than a caravan, so again this can effectively be ignored in this instance.
As most caravans present a majority resistive load, we can use simple Ohms law heating calculations.
Every electrical cable has some resistance. Resistance opposes the passage of a current, and in doing so the lost current is released as heat. The standard EHU cable has conductors of 2.5csa will have a resistive value of about 0.007Ohms per meter for each conductor.
From:
http://www.nktcables.com/dk/products/railway/railway/technical-information/~/media/Files/NktCables/Products/UK/Railway/technical%20info/Copper-wire-table.ashx
Because the same current flows in both Live and Neutral conductors you have to double the value to 0.014Ohm per meter of EHU cable. The earth conductor should not have any current flowing, so it will not produce heat.
As we are have Current and resistance, Ohms law tells the energy (heat) is the calculated by the Current squared times the resistance. If the cable was carrying its full rated current of 16A then we would get heat losses of 16A x 16A x 0.014Ohms = 3.584Watts per Meter
For a full 25M EHU that would be 89.6W. Do you remember how hot a 40W light bulb got well this is two and a bit light bulbs of heat. If this was tightly coiled you can imagine how hot it can get. But that is if it is carrying the full 16A, which most of the time it won't be.
The kinks in a cable can start to produce problems if the conductors have been constantly stressed they can start to stretch and loose csa which raises the resistance at that point. This can lead to a hot spot in the cable as well as the damage to the insulation mentioned by others.
The standard EHU cable uses PVC on PVC insulation and will be rated for a maximum surface temperature of 70C. BUT If a cable self heats and is produces 70C surface surface temperature, it must be significantly hotter inside, and that will be enough to deform the insulation and reduce its effectiveness, rendering dangers of electric shock as the insulation may have thinned.
I would prefer to see the coil in the picture spread out a bit more so it is better able to lose heat more effectively. The kinks should also be avoided to prolong the life of the EHU.
The advice about uncoiling cables is principally aimed at cables that are tightly coiled on a drum or more particularly in an enclosed drum, where there is little means to let the heat escape which can cause a temperature build up. This can start a cascade reaction because as copper heats up its resistance increases, which means for any given current more energy will be lost in the cable generating even more heat. The corollary of this is as the resistance rises less current will pass for a given supply voltage, but that is not an excuse to leave power cables tightly coiled when in use.
- Jun 20, 2005
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Many thanks to my learned forumites for all their words of wisdom and highly technical explanations.
For the sake of a newbie can I say as a rule of thumb , for me since 1978, the cable should be used in an uncoiled position. :kiss:
I'm happy to run a referendum :cheer:
For the sake of a newbie can I say as a rule of thumb , for me since 1978, the cable should be used in an uncoiled position. :kiss:
I'm happy to run a referendum :cheer:
- Jul 15, 2008
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I remember 1978.......the year my son was born
Virtually no one had a computer or a mobile phone.......and you had to wait in queues while people in front of you at a cash desk had their credit card put through a roller machine to produce a paper payment slip.
MCB's and RCBO's were not common and we all had to know how to fit fuse wire of the right amperage into a plug in ceramic holder.
Nowadays use a proper purpose designed EHU cable at a Local Authority licensed Campsite and there is very little danger from the cable overheating.
I never tightly coil my cable anyway even in storage, and I certainly would not wind it on a drum.
Virtually no one had a computer or a mobile phone.......and you had to wait in queues while people in front of you at a cash desk had their credit card put through a roller machine to produce a paper payment slip.
MCB's and RCBO's were not common and we all had to know how to fit fuse wire of the right amperage into a plug in ceramic holder.
Nowadays use a proper purpose designed EHU cable at a Local Authority licensed Campsite and there is very little danger from the cable overheating.
I never tightly coil my cable anyway even in storage, and I certainly would not wind it on a drum.
Raywood said:
Well said Ray. I have never seen 'tightly wrapped coils' on site, for it is impossible to do, and I defy anyone to manage it to the point where they could actually generate anything like enough heat for a fire. The only time this is likely is if the cable is damaged to the point where the conductors within could short, when it wouldn't matter if coiled or not.
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