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?

 

[Folkranger]

Leaving it coiled doesn't generate any more heat, just the heat is concentrated and can't escape, so the temperature will rise.

If it's a chunky cable and they're only using a few amps, then the risk is low. But if you've got electric heating turned up to max, and then you're running an electrical cooking appliance... it's probably not clever.

I was under the opinion that coiled cables do generate more heat. After all that's how you make an electric fire element, you coil a wire tightly and put a heavy current through it. It heats more than the uncoiled wire ever could.

 

[scotjimland]

So they know that people will ignore the reeled limit, hence the thermal cut-out

yes, as we know they do... but as I mentioned before, 'some' may not appreciate or know how loads add up .. ignorance is not always bliss

 

[Folkranger]

The French seem to use coiled cables a lot.
I’m not an electrician but maybe the cable and the amount of power going thru it makes a difference as in some people don’t run high powered cooking appliances.
If you’re only running the fridge, the hot water (only turns on/off) kettle, most of the time it wouldn’t matter that your cable is coiled or not!
Our cable is always laid out flat…..when we use it!

In my experience the French have extension on extension run through multiple adapers and splitters using two pin plugs and often in reverse polarity so not a good example.

 

[Bodoge]

So that suggests only 4A when fully reeled.

Germans next door to us here in playa montroig have the same thick coiled up EHU Lead.

But they don’t wash, clean, shower in the motorhome. It’s also got those seasonal registration plates, so will probably going into hibernation from next month.

In my experience the French have extension on extension run through multiple adapers and splitters using two pin plugs and often in reverse polarity so not a good example.

In my opinion, in theory the French domestic electrical system is far better than the UK 13A + 3plate system, but as you rightly point out the French abuse the system same as the Brits in UK. Relatively speaking earthing in France is a new phenomena as before the white goods invasion most electrical appliances were double insulated. Having fitted many French switches and sockets, my opinion is that Barnie Rubble designed them.

^{_{Subscribers  do not see these advertisements}}

 

[gus-lopez]

Most Europe vans don’t have an option to run boiler on mains electric.

I doubt a german van would have anything other than the fridge & charger on electric.certainly no cooker or water heating

So that suggests only 4A when fully reeled.

I fail to see what you are all looking at? It states, & in english,
"1kw when reeled up"

It can't be 4kw as it is only 3kw when fully unwound?

 

[enark]

Inductance should play no part in this case. Inductance from the coiled L will be cancelled by the coiled N and anyway a metal core would need to be involved.

I speak from experience, trust me it does.

 

[scotjimland]

I fail to see what you are all looking at? It states, & in english,
"1kw when reeled up"

It can't be 4kw as it is only 3kw when fully unwound?

He said 4 amps .. when reeled up..not 4kw

 

[Widge]

I was under the opinion that coiled cables do generate more heat. After all that's how you make an electric fire element, you coil a wire tightly and put a heavy current through it. It heats more than the uncoiled wire ever could.

The reason an electrical element is coiled is becouse it would be about 10m long if it wasn't, not very practical to use.

 

[pappajohn]

I removed this from our house lighting wiring.
Cause....a loose connector screw.

^{_{Subscribers  do not see these advertisements}}

 

[Richard n Ann]

I speak from experience, trust me it does.

There is no magnetic field round a flex. That's why clamp meters register zero on a flex. Don't know what you experienced

 

[PP Bear]

Where/when were you working in Oman?

In the Army, so a number of times over the years, either training for desert warfare, or training the Oman Army in various tasks, so between 2002-2020.

Nephew is an Army Major and is now stationed with the Oman Army as well.

 

[Revolvor]

In the Army, so a number of times over the years, either training for desert warfare, or training the Oman Army in various tasks, so between 2002-2020.

Nephew is an Army Major and is now stationed with the Oman Army as well.

We were there much earlier -1979 to 1982 and then 6 months in Abu Dhabi. I worked for BAe as a service engineer for Rapier, operated by the Air Force, based near the airport at Seeb. I was there with my wife and daughter. Our oldest son was born while we were out there. Working hours were 6:00am to 1:00pm, 6 days a week, so we spent a lot of afternoons at the Officers Beach Club. I also joined the BSAC which had a branch based at the club.

In my spare time I renovated a VW bus, bought from a scrap yard. We turned it into a camper and then at the end of our contact we drove it back to UK. It took us 5 weeks, with a 5 and 1 year old.

We thought Oman was wonderful and enjoyed the opportunity to really off-road and explore. I loved the fact that if we were driving and say an interesting feature miles off the road, we could just turn off the road and drive there. We had full use of a Land cruiser with free fuel!

 

[NR]

100% uncoiled.

 

[enark]

There is no magnetic field round a flex. That's why clamp meters register zero on a flex. Don't know what you experienced

Seen many uncoiled cables melt and burst into flames. Agree with what you say regarding a clamp meter, but think you will find the coil increases inductance which therefore increases impedance which increases the heat produced…..hence fire.

experienced from twenty plus years of field electrical systems, not amateur motor homing, but the principle is the same.

^{_{Subscribers  do not see these advertisements}}

 

[Richard n Ann]

increases impedance which increases the heat produced…..hence fire.

Surely if impedance goes up current goes down?
autorouter what do you think?

 

[enark]

Surely if impedance goes up current goes down?
autorouter what do you think?

Of course it does, hence the increased heat…..guess you’re a sparky?

 

[Widge]

Although probably insignificant in a 20m extension cable it will have inductance and capacitance when used for AC.

Dont ask me to explain the science, but years ago my brother had to design a three phase amplifier for testing the big heavy duty armoured high tension cables used for underground three phase supplies, not unlike the three core extension cable but about 8cm in diameter. The CEGB had tried to develop their own using three high quality 100w transistor audio power amplifiers to drive the test signal along the cables, but the amplifiers kept failing.

They approached Radford Electronics in Bristol who at that time built high quality test equipment and audio amplifiers. My brother who ran the test equipment side of the company at the time, but also an experienced engineer diagnosed the problem, the cables (which were very long) had very high inductance and capacitance, which conventional transistor amplifiers do not like causing the failures.

His solution was to develop specialised valve power amplifiers to drive the signals down the cable, as a valve design can handle highly reactive loads much better than transistor amplifiers.

 

[Tombola]

It's a no brainer...unwind it.
We we're lucky. Be careful

We done the same with our hose once..then all inside of it froze solid middle of summer cos we ran it too long jetting the van.

 

[autorouter]

the coil increases inductance which therefore increases impedance which increases the heat produced

Inductance is caused by the buildup and collapse of magnetic fields. An ordinary wirewound resistor is made by winding a length of resistance wire round a bit of non-conductive ceramic. Because the current spirals one way, it acts as a coil, generates a magnetic field and has a relatively high inductance.

If you take the same length of resistance wire, fold it in half, and wrap it round the same bit of non-conductive ceramic, the two wire ends will finish at the same end of the ceramic bit. The current will spiral one way to the top of the resistor, and the opposite way back to the bottom of the resistor. The two magnetic fields will cancel each other out, so very little net magnetic field. Because there is no magnetic field there is no inductance. This type of resistor is 'non-inductively wound', and has a very low (almost zero) inductance.

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.

If you buy a complete coiled mains cable on a reel, it will have two amps ratings. Typically if it's 10A fully unwound, then its wound rating is about 4A. However if the cable and reel are bought separately there will be no warning about the problem, and some people find out the hard way that a wound-up cable can heat up, melt and possibly cause a fire.

^{_{Subscribers  do not see these advertisements}}

 

[Charente16]

We were there much earlier -1979 to 1982 and then 6 months in Abu Dhabi. I worked for BAe as a service engineer for Rapier, operated by the Air Force, based near the airport at Seeb. I was there with my wife and daughter. Our oldest son was born while we were out there. Working hours were 6:00am to 1:00pm, 6 days a week, so we spent a lot of afternoons at the Officers Beach Club. I also joined the BSAC which had a branch based at the club.

In my spare time I renovated a VW bus, bought from a scrap yard. We turned it into a camper and then at the end of our contact we drove it back to UK. It took us 5 weeks, with a 5 and 1 year old.

We thought Oman was wonderful and enjoyed the opportunity to really off-road and explore. I loved the fact that if we were driving and say an interesting feature miles off the road, we could just turn off the road and drive there. We had full use of a Land cruiser with free fuel!

You didn't mention the 'best thing' about Oman which is the people. Lived in the Gulf (UAE) for twenty - five years and the Omanis are the nicest people, even the gouvernment officials. Last job was the new Guest Palace for HH on the site of the old British Residency. Used to vist the various military clubs' and the Golf Course with a Pass from the Ruler's Office.

Happy Days.

 

[PP Bear]

All this talk of impotence and stuff like that, it’s just magic and you plug one end of the thingy in that thingy and the other end of the thingy into the van and hey presto, my coffee machine works…….but, always completely unroll the magic thingy first. Tis for that reason I carry 3 of the magic thingys, with 2 at 25 meters and 1 at 14 meters, for those closer magic receptacles.

 

[Revolvor]

You didn't mention the 'best thing' about Oman which is the people. Lived in the Gulf (UAE) for twenty - five years and the Omanis are the nicest people, even the gouvernment officials. Last job was the new Guest Palace for HH on the site of the old British Residency. Used to vist the various military clubs' and the Golf Course with a Pass from the Ruler's Office.

Happy Days.

You are right. I thought that after re-reading my post later.

One example was the Omani store man at our workshops who invited the whole team + families to his son's 1st birthday party at their house on a date plantation. He was worried about protocol regarding serving the food - normally it would be men first, but he decided on European women and children, then European men, then Omani men and last, Omani women and children.

On another occasion, my daughter had a medical emergency on a Friday, and the doctor said we had to fly back to UK that night! Our passports were in immigration having new visas, but the Air force arranged for a helicopter to fly to an immigration official's house to pick him up and take him to the (closed) office to retrieve them!

I can't see that happening with the UK passport office!

(The medical emergency was a false alarm when we got to a UK hospital the next day)

 

[Widge]

Inductance is caused by the buildup and collapse of magnetic fields. An ordinary wirewound resistor is made by winding a length of resistance wire round a bit of non-conductive ceramic. Because the current spirals one way, it acts as a coil, generates a magnetic field and has a relatively high inductance.

If you take the same length of resistance wire, fold it in half, and wrap it round the same bit of non-conductive ceramic, the two wire ends will finish at the same end of the ceramic bit. The current will spiral one way to the top of the resistor, and the opposite way back to the bottom of the resistor. The two magnetic fields will cancel each other out, so very little net magnetic field. Because there is no magnetic field there is no inductance. This type of resistor is 'non-inductively wound', and has a very low (almost zero) inductance.

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.

If you buy a complete coiled mains cable on a reel, it will have two amps ratings. Typically if it's 10A fully unwound, then its wound rating is about 4A. However if the cable and reel are bought separately there will be no warning about the problem, and some people find out the hard way that a wound-up cable can heat up, melt and possibly cause a fire.

But as i mentioned before, the max current rating is the maximum continuous current the cable can handle, while not exceeding the maximum operating tempreture, typicaly 70°C while being well ventilated in an ambient temperature of typicaly 30°C. Run a black extention across hardcore in full sun when it is 40°C in the shade, and the cable is probably upto 50 or 60°C before you even turn anything on.

 

[Dolmen]

I tend to uncoil simply to stop the busy bodies stopping to tut to each other as they walk past the van. My heavy duty 16 amp cable on a fairly big real has never generated any heat detectable to touch even when using electric heater and hot water, regardless what’s a little unravelling and rewinding to keep the peace. Less of a problem when travelling through Europe as nobody unwinds this spindly little cables they use.

^{_{Subscribers  do not see these advertisements}}

 

[The Wino]

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.

 

[Richard n Ann]

guess you’re a sparky?

Certainly not

 

[Widge]

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.

It is still not good practice, but for most campers, the camper on average dosen't draw very much, but using things like kettles toasters could quite possibly push the tempreture much higher than the safe operating tempretures but just for a short time, and although this may not cause a catastrophic failure, it is very likely to degrade the plastic over time shortening its life, most of these cases people junk the lead becouse you can visably see the cable is cracked or degraded, the unfortunate few find out the hard way when their cable fuses, and trips out the supply, you would have to be very unlucky for it to catch fire and set your van on fire, but for the sake of 5 minutes to unroll it or having a shorter lead available as well, why take the risk. I can quite imagine an insurance company refusing to pay out when they discovered it was a coiled cable stowed under the van that caused the fire.

 

[The Wino]

It is still not good practice, but for most campers, the camper on average dosen't draw very much, but using things like kettles toasters could quite possibly push the tempreture much higher than the safe operating tempretures but just for a short time, and although this may not cause a catastrophic failure, it is very likely to degrade the plastic over time shortening its life, most of these cases people junk the lead becouse you can visably see the cable is cracked or degraded, the unfortunate few find out the hard way when their cable fuses, and trips out the supply, you would have to be very unlucky for it to catch fire and set your van on fire, but for the sake of 5 minutes to unroll it or having a shorter lead available as well, why take the risk. I can quite imagine an insurance company refusing to pay out when they discovered it was a coiled cable stowed under the van that caused the fire.

I'm not saying people shouldn't unroll the cable if they want but how many incidents are there has anyone seen a motorhome fire due to an unrolled cable? By comparison there's a lot of angst today about reducing the speed limits in Wales when there are proven increases in fatal accidents at 30 compared to 20 and on an average journey the extra time taken would be about the same as unrolling a cable!

 

[tonyidle]

I don't really understand this rolling up of cables. I collect mine in loose loops allowing for its memory from being originally supplied on a coil. If I lie the loose coil on the ground it doesn't tangle when extended to the EHU point.

^{_{Subscribers  do not see these advertisements}}

 

[Ray-Vic]

This is no different to domestic or commercial cabling. Bury a cable in a wall or under insulation and it affects the rating. When calculating a circuit you consider the environment in which the cable is run.

Coiled cables in isolation are not necessarily a problem, you can buy coily extension leads rated at 13A, but when tightly coiled on a drum the cable isn't rated the same as when it's not.