Unrolling electrical hook up cables: safety concerns?

[redchad]

Question for everyone! We’re currently in Germany and have noticed that certainly the Germans but also Norwegian and Italian vans are all using roll up hookup cables as in the picture. Now at home were constantly warned about fully unrolling your cable as it could get to hit and burst into flames. So who’s right and who’s wrong as the Germans don’t seem concerned?

 

[bigtwin]

A coiled up mains cable has the current spiralling one way along the live wire, through the appliance, and back the opposite way along the neutral wire. The currents are equal and opposite, causing two equal and opposite magnetic fields, which cancel each other out. The net result is a very small, practically zero, inductance.

However a mains cable has a small but non-zero resistance. This resistance causes heat, distributed along the length of the cable. For example a typical 25m length of mains cable carrying 16A of current generates about 44W if 2.5 mm sq, and about 74W if 1.5mm sq. When the cable is unwound, this heat escapes and causes no problem. If tightly wound on a coil, the heat can't escape easily, and builds up. It can even build up so much that the plastic insulation melts.

A very good explanation of why inductance doesn’t cause a problem and it nicely supports statements I made earlier. There seems, however, some reluctance to acknowledge this.

Ian

 

[enark]

A very good explanation of why inductance doesn’t cause a problem and it nicely supports statements I made earlier. There seems, however, some reluctance to acknowledge this.

Ian

Cus you’re all ignoring the loading dynamics…..

anyway greater brains than ours have long decreed that mains supply cables for mobile field electrical systems are to be uncoiled prior to use - billy basic SOPs, probably at least dating back to WW2.

if your happy in your ignorance to use mains cables still coiled, no probs, just hope your not parked to close to me when it bursts into flames one dark night (when your heater/water heater/kettle/microwave may kick in).

 

[Dolmen]

Cus you’re all ignoring the loading dynamics…..

anyway greater brains than ours have long decreed that mains supply cables for mobile field electrical systems are to be uncoiled prior to use - billy basic SOPs, probably at least dating back to WW2.

if your happy in your ignorance to use mains cables still coiled, no probs, just hope your not parked to close to me when it bursts into flames one dark night (when your heater/water heater/kettle/microwave may kick in).

A bit over the top, don’t you think, out of the 100’s of thousands of nights spent each year by motorhomers on ehu it is difficult to find reports of any going up in flames so I wouldn’t worry about someone parking close to you, seems motorhomes have many more mishaps than coiled ehu cable. I do, however, uncoil because I know how much people fret over these sort of things.

 

[bigtwin]

if your happy in your ignorance to use mains cables still coiled,

I always uncoil (unless there’s a risk of frost).

Cus you’re all ignoring the loading dynamics…..

How dynamic are those dynamics that you’re referring to?

when your heater/water heater/kettle/microwave may kick in).

These?

Ian

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[The Wino]

As we don't have an electric kettle or an electric space heater or a toaster or a microwave and have never seen any MH out of the thousands I've seen with coiled up cables have a problem I'm wondering why I bother unwinding our cable other than to keep curtain twitchers quiet!

 

[scotjimland]

As we don't have an electric kettle or an electric space heater or a toaster or a microwave and have never seen any MH out of the thousands I've seen with coiled up cables have a problem I'm wondering why I bother unwinding our cable other than to keep curtain twitchers quiet!

leave it coiled then wait for the curtain twitcher to knock you up.. then point to end you haven't plugged in..

 

[Landy Andy]

As we don't have an electric kettle or an electric space heater or a toaster or a microwave and have never seen any MH out of the thousands I've seen with coiled up cables have a problem I'm wondering why I bother unwinding our cable other than to keep curtain twitchers quiet!

I’ve never been “warned“ about mine being still wound up. May even keep them away.

 

[autorouter]

Lots of people say they have seen lots of motorhomes using wound up cable and it's really dangerous but if it is why haven't lots of people seen problems because of it? Is it like reverse polarity something only Brits worry about and everyone else ignores seemingly without any great number of incidents.

Most people only use electricity at low amps, for a fridge for example. Or for high amps for a few minutes, like a kettle, microwave, hairdryer etc. A wound up cable is fine for low amps. There's no way it will get hot on a 5A supply, for example. The problem tends to arise if you are using a heater for a long period, as in winter with a poorly insulated van. And even if there is a problem, usually the plastic melts and the RCD or MCB trips before a fire starts up.

 

[cyberyacht]

Mine is in big loops, coiled like mooring ropes and hangs on a hook in the garage until required. A hangover from my yachting days. You wouldn't have time to put ropes on and off a drum.

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[Widge]

Most people only use electricity at low amps, for a fridge for example. Or for high amps for a few minutes, like a kettle, microwave, hairdryer etc. A wound up cable is fine for low amps. There's no way it will get hot on a 5A supply, for example. The problem tends to arise if you are using a heater for a long period, as in winter with a poorly insulated van. And even if there is a problem, usually the plastic melts and the RCD or MCB trips before a fire starts up.

Most people only use electricity at low amps, for a fridge for example. Or for high amps for a few minutes, like a kettle, microwave, hairdryer etc. A wound up cable is fine for low amps. There's no way it will get hot on a 5A supply, for example. The problem tends to arise if you are using a heater for a long period, as in winter with a poorly insulated van. And even if there is a problem, usually the plastic melts and the RCD or MCB trips before a fire starts up.

A heater in winter, is probably less of a problem becouse the outside temperature will be low, but maybe an A/C in summer when the cable is already upto 40 or 50°C might be different.

 

[nigel dewbery]

Question for everyone! We’re currently in Germany and have noticed that certainly the Germans but also Norwegian and Italian vans are all using roll up hookup cables as in the picture. Now at home were constantly warned about fully unrolling your cable as it could get to hit and burst into flames. So who’s right and who’s wrong as the Germans don’t seem concerned?View attachment 809153

Speaking as an electrician this depends on three things, the current being drawn, the size of the conductors within the cable and the ambient external temperature
My original cable was a 2.5mm 3 core which is rated at 30amps, I recently bought one(as a back up) supposeably the same and it was 1.5mm cable so only rated at 16amp
Needless to say the latter one I would uncoil in the uk whereas the former I don’t worry
On the continental 6amps I doubt worry but keep any coil out of direct sunlight

 

[sarumsteve]

Whilst we're yet to take our van abroad, I understand that many sites abroad offer lower current hookups (perhaps 6A) rather than the standard 13A we generally get in the UK. That may mean it's seen as less of an issue if they're not used to being able to draw as much current as some seem to use in the UK.

Some extension reels (normal household ones, not EHU specifically) have two ratings on them - coiled and uncoiled. Less current travelling through the cable means less potential to heat up to a dangerous level, so it could be argued that it's safe enough provided only a small amount of current is being drawn. However, use a heater/kettle/beefy battery charger etc and you could start to draw enough current to have an issue.

I'm not an electrician so it's just an opinion.... personally I wouldn't use one coiled up like that right next to my van - whilst the probablilty of an issue might be low, the impact of having an issue would be huge, especially if we were asleep at the time a fire started!

 

[sarumsteve]

I always unroll after seeing an unwound extension in a freezing cold building in january powering a kettle catch fire. Why take the risk?

 

[Adeydub]

I guess it's a case of...

do the right thing, wound cables can overheat, melt and catch fire...

you know it makes sense ..

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[Adeydub]

Depends on load, when cable is coiled it’s an inductor so magnetic fields act like a small induction cooker and therefore gets hot. Obviously as load ( current) increases it will get hotter especially with lower rated (thinner) cables

Very rare to burst into flames because of modern insulation materials but I have seen examples where cables have fused together and if there is something flammable nearby then there could be a problem

I think it’s a good discipline to just keep cable tidy and free of any tight coils, it also makes it much easier to coil up the cable when you’re packing up

 

[Ian Bosman]

Yes I get it but there all doing it.

View attachment 809163

it is all a matter of the current you are drawing, the larger it is the more likely to overheat but we all subject to the 16amp limit on ehu

 

[MikeMex]

I think I would position the reel away from the van, just in case.

Why risk it? Just uncoil every time and you minimise the risk. Any excess cable, just neatly lay it out 2 and fro in long lengths.

I think I would position the reel away from the van, just in case.

Why risk it? Uncoil every time and minimise the risk. Any excess cable, run in long lengths to-and-fro.

 

[autorouter]

when cable is coiled it’s an inductor so magnetic fields act like a small induction cooker and therefore gets hot.

So can you explain which bit in post #79 I got wrong?

 

[mikeg40]

I carry a 5m cable as well as a 25m one so I don't always have to unroll/re roll the longer one. I've seen the effects of using uncoiled - not worth the risk, IMHO

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[dawsey]

Interesting, as ever a lot of strong opinion, even after posts illustrating the typical lower rating of wound cables vs unwound and a decent explanation of the reason a wound cable is typically rated far lower (inability to dissipate heat) from autorouter.

The OP posed the question why do the German vans he sees often use would cables. The Germans, being Germans will just follow the instructions by the cable manufacturer, and ensure they limit draw to ~ 4A when using the EHU cable wound.

It is interesting when people say “but if there is an EHU I will switch my water to electric, switch my heating to electric, use my electric kettle and my electric cooker, switch on AC” etc etc. Presumably also acquire and use an electric canopy heater etc… Here we have the reason why campsite EHU charges have become so high - because of people like that who simply take the mickey.

Roll on metered pitches - this is coming because it has to, due to electric cars. The campsites will be very happy to charge for consumption, with those Germans with their ‘dangerous’ coiled cables considerately using site electric only for lighting and charging but now paying a fraction of what those with patio heaters then pay.

Something tells me that the use of patio heaters and the near continuous extraction of the full 10 or 16A will reduce when all pitches are metered, and we shall all be happily (and safely) using coiled cables….

 

[cyberyacht]

You can bet your life that, in the UK, the pitch fees won't come down significantly with the introduction of metering. They might knock a quid off and tell you they are doing you a favour.

 

[Jim]

with those Germans with their ‘dangerous’ coiled cables considerately using site electric only for lighting and charging but now paying a fraction of what those with patio heaters then pay.

What I know about Germans after living in Germany for almost three years is they are the pretty much just like us. Uncannily so, only our language separates us and much of that is the same. So many of them, just like many Brits, will certainly not be using gas to heat their water if they are already paying for an electricity supply.

IMO the only reason you see so many coiled cables over the water is because 6 amp supplies are so common, so coils are not an issue.

 

[ontheroadagain]

The extension cable that I use at home (not on motorhome) states 5A wound, 13A unwound, so it can be used wound up if the load is less than 5A.

 

[Widge]

The extension cable that I use at home (not on motorhome) states 5A wound, 13A unwound, so it can be used wound up if the load is less than 5A.

And if the ambient tempreture is probably no more than 30°C.

Also what about fault conditions, equipment doesn't always die, drawing no current, or short causing the fuse or breaker to go. A faulty leisure battery could cause the charger to draw a lot more current than you think it is for example.

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[herald_400rl]

My MIL rang a few years ago to have a look at her dryer as it kept "tripping the electrics". When I got there and she showed me what she meant, there was a 15m reel extension lead (the ones in the boxes) with about 2m unreeled to reach the socket. When the dryer had been on for a bit it "tripped" so she had to press the red reset button on the reel... the thermal trip... when I uncoiled it I had to use an oven glove as it was so hot toward the middle you couldn't touch it.

 

[Scubaclive]

cables are never rated for "coiled operation" in any chart I have come across

but happy to be corrected..

Printed in the cable reel
720w fully wound
3120w fully unwound

 

[SpeedyDux]

Also remember that what it is wound on will make a difference, if the reel has a big chunky metal axle that will also change the characteristics. Also a three way fridge will probably draw between 1 and 2 amps, add that to your charger, tv, notebook etc it is suprising how it all ads up.

I just have a couple of shorter leads that i just manually coil up, usualy one or both joined together is enough for most sites.

CAMC rules ban joining 2 EHU cables. That seems a bit too nanny-ish. You can use waterproof covers for the connection.

I see a few Members using coiled EHU cables each time I am on one of their sites. That safety problem tends to be ignored by Wardens.

 

[scotjimland]

Printed in the cable reel
720w fully wound
3120w fully unwound

View attachment 811620

please read my post again.. you may have misread..

I said cables, not cable reel..

cables are never rated for "coiled operation" in any chart I have come across

 

[Gromett]

cables are never rated for "coiled operation" in any chart I have come across

but happy to be corrected..

I don't think it is the cable that has the rating but the final product where the cable is used. Here is an example. you can see the rating next to the thermal cutout.
I just had a quick scan through and pretty much all of them on amazon have this.

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[scotjimland]

I don't think it is the cable that has the rating but the final product where the cable is used. Here is an example. you can see the rating next to the thermal cutout.
I just had a quick scan through and pretty much all of them on amazon have this.

View attachment 811629

I thought you would have understood what I said...

I was referring to Cables... not cable reels ..

manufactuers cable charts have rating information on installation methods .. but not for coiled use.. never seen that

I do not use Amazon as a source of technical information..