Unrolling Mains Hook-up leads

[pepe63xnotuse]

armstrongpiper - 2016-03-30 4:17 PM

 

OK, some interesting views expressed, and thankyou. I think there's a bit of the 'Urban Myth' exaggeration involved, but no doubt it is preferable to have some ventilation around the cable especially if the current flowing is 'highish'.

 

Armstrongpiper

 

There didn't appear to much in the way of "urban myth" in the link supplied by paulmold :-S

 

http://www.bbc.co.uk/news/uk-wales-north-west-wales-15940837

[Cliffy]

 

 

I used to be sceptical about having to uncoil cables until on a very cold in Scotland we pulled in to the campsite at Avimore I quickly nipped out and plugged us in the EHU was right next to the socket on the van so I only unwound a couple of foot of lead. in the morning when we went to leave the cable spool was smoking, the cable was so hot I could not touch it, we had to wait an hour for it to cool down enough to put in the locker. When I got home I tried to uncoil the cable but it was almost a solid lump of rubber and copper.

 

I always fully uncoil the lead now when we are going to use the electric heater, boiler and hob.

 

 

 

[Colin Leake]

All you need to do is always start from one fixed point say by plugging the motorhome end in when you uncoil the lead. When you coil it back up do it in reverse starting from the other end. This prevents twists building up in the cable. I've been doing this for years with no tangles.

[Bulletguy]

Dave225 - 2016-03-29 7:15 PM

 

One thing I have noticed, and I always fully unwind it, is that trying to rewind it up again can be a pain as the lead coils itself up into loops which are fun to straighten.

 

However, I also suspect that part of the confusion can be laid at the doors of our EU neighbours who always it seems travel with leads on spools and rarely unwind more than what they need. Their cable is of a lower wattage than ours and seems more flexible. Certainly it is not as rigid as the orange one we use here. I have not heard of any major disasters with what they are doing so I guess it is an 'approved' method.

 

I've noticed the same too. EU motorhome folk use cable more like our domestic mains cable. Easily wound, easily packed. The orange EHU cable us brits use is much thicker, extremely heavy making it a maul of a job when packing away, and an absolute pain in the proverbial to coil successfully. Having a PVC means space is at a premium so there isn't anywhere to store a reeled winder which are too bulky. I tried a flat plastic thing off fleabay which would easily take domestic cable thickness, but NOT enough room on it for the orange cable.

[Derek Uzzell]

armstrongpiper - 2016-03-30 4:17 PM

 

OK, some interesting views expressed, and thankyou. I think there's a bit of the 'Urban Myth' exaggeration involved, but no doubt it is preferable to have some ventilation around the cable especially if the current flowing is 'highish'.

 

Armstrongpiper

 

Obviously I don’t know what provoked you to ask your original question, but I note that there’s a "MAINS HOOK-UP” article in the April 2016 Caravan Club Magazine (Pages 105/106).

 

This article includes a TOP TIPS list that begins “Never leave spare cable tightly wound on a drum” and there’s a photo of a fully unwound cable with the advice “Unwind the whole cable so that it sits loosely under your vehicle to avoid overheating”. Another photo in the article shows what’s clearly a long hook-up cable tightly wound on to the device in the attached picture.

 

I can’t see any ‘myth’ being involved here - a long length of tightly wound mains hook-up cable will heat up significantly if the current demand is high and unwinding the cable fully will prevent this.

[Bulletguy]

Derek Uzzell - 2016-03-31 9:20 AM

 

armstrongpiper - 2016-03-30 4:17 PM

 

OK, some interesting views expressed, and thankyou. I think there's a bit of the 'Urban Myth' exaggeration involved, but no doubt it is preferable to have some ventilation around the cable especially if the current flowing is 'highish'.

 

Armstrongpiper

 

Obviously I don’t know what provoked you to ask your original question, but I note that there’s a "MAINS HOOK-UP” article in the April 2016 Caravan Club Magazine (Pages 105/106).

 

This article includes a TOP TIPS list that begins “Never leave spare cable tightly wound on a drum” and there’s a photo of a fully unwound cable with the advice “Unwind the whole cable so that it sits loosely under your vehicle to avoid overheating”. Another photo in the article shows what’s clearly a long hook-up cable tightly wound on to the device in the attached picture.

 

So glad you posted that photo Derek as that's the identical plastic winder thing i bought off fleabay which is fine for short lengths of the orange cable, but useless for 'average' lengths (not sure what mine is) as it won't fit on! Domestic mains cable no problem....bags of room, but not the orange HU cable.

 

You are right about the heat though. I have a 50ft mains extension lead on a purpose made cable winder (see attachment) which i use for a garden vac. Leave a few feet wound on and it soon heats up. I completely uncoil mine every time which avoids that......but then it's not a problem as it's so simple and light in weight because its domestic, to wind back on the drum.

 

 

[Brian Kirby]

All cables heat to some extent when passing current. The closer the current to the rated capacity of the cable, the more heat will be generated. Usually, with an uncoiled cable in free air, and a load that is within its rated capacity, the heating will be imperceptible.

 

OTOH, when coiled on a drum, such as that shown in the post above, heat from each turn of the cable cannot be dissipated and, if being run at or near its rated capacity, will build up to the point at which either the cable catches fire.

 

The fail safe advice is, therefore, to fully unwind the cable.

 

If you know the wattage you are consuming, and that it is below the rating for a fully wound cable as stated on the drum, the coiled cable may become slightly warm, but that is all. Go over that limit and the risk of melted or burning cable rises in proportion to the current's proximity to the cable's rating. It would be unwise to assume that uncoiling a bit would allow increased current to be drawn. My understanding is that it doesn't work like that, because whatever cable is left on the drum still can't dissipate its heat.

 

There is no urban myth in this: it is fact.

 

The reason some have problems and others don't is in part luck, where the user's understanding of electricity is lacking but they have a heavy duty cable and light consumption, and understanding, where the user knows his/her consumption and its relationship to the safe capacity of the coiled cable. If unsure, or if you don't fully understand, simply uncoil the cable. A flaming cable drum under your van is not to be taken lightly!

[Will H]

OTOH ?

[Dr Dave]

Will H - 2016-04-01 6:12 PM

 

OTOH ?

On The Other Hand

[Will H]

Amazing. I've not studied sign language.

[Muswell]

.....and as the cable heats up the cable resistance increases, which in turn increases the heat generation.

[Derek Uzzell]

Will H - 2016-04-01 6:19 PM

 

Amazing. I've not studied sign language.

 

Nor GOOGLE apparently... ;-)

 

https://www.google.co.uk/?gfe_rd=ssl&ei=VXr_VoWMD5OFaMjQnZgF#q=otoh

 

For future reference

 

http://www.netlingo.com/acronyms.php

 

 

 

[Will H]

Derek,

 

Yes I did investigate Google. But why should I have to when highly educated persons (so called) cannot be bothered to write in simple English. I just don't get it !

 

I shall say no more

 

Will

[Will H]

Back to the original problem.

 

I see a vast difference in the winding of a close coiled cable in an enclosed plastic container compared to the open hand held flat cable holder as pictured. a while back.

 

I assume the open to air coiled cable is wound OBLONG wise not coiled in a true CIRCLE and therefore is less likely to be a problem. I can see that if the cable is lengthy it may end up being rather circular.

 

Can someone please confirm if there is a difference between circular wound and oblong wound wiring?

 

Will

[Brambles]

Will H - 2016-04-02 9:32 AM

 

Derek,

 

Yes I did investigate Google. But why should I have to when highly educated persons (so called) cannot be bothered to write in simple English. I just don't get it !

 

I shall say no more

 

Will

 

IMHO because other peeps who post on the thread are NOT PAID for contributing and GTTG. So yes, you should google words or abbs YDNU or at least AP.

 

[pepe63xnotuse]

As I posted very early in the thread, even our quite loosely coiled (hand-looped, circular, "lasso" style), got very warm (and that was just laying on the cold ground).

 

OT - I ended up using one of these-

https://www.cybermarket.co.uk/adam-hall-cable-drum-small-p-857948.html

(not from there though and not for 27 quid!?..I though ours was around 12-15?,,)

 

A bit bulky but it fit nicely into the lockers of the two *CBs we had

(*in fact in the smaller one, it was able to remain secured in the locker, with the cable just drawn off it..FULLY!).

[malc d]

Will H - 2016-04-02 9:32 AM

 

Derek,

 

Yes I did investigate Google. But why should I have to when highly educated persons (so called) cannot be bothered to write in simple English. I just don't get it !

 

I shall say no more

 

Will

 

 

You should appreciate Will that some people are so busy that they do not have time to type complete words.

 

( You can always ignore them ).

 

;-)

[Brambles]

"Can someone please confirm if there is a difference between circular wound and oblong wound wiring?

Will"

 

Not a big difference as the inner coils are still insulated against cooling by the outer loops of the cable.

PVC has quite a low conductivity of heat so just a cable with a few layers of other cable around it means it will get just as hot in places compared to the enclosed coil as you call it. Yes the 'enclosed coil' could get get warmer but does not negate the problem by having and exposed coil.

[Will H]

Thanks. I shall continue on my merry way doing as I always have by laying the cable up and down lengthwise at the side of the van, however odd it may seem to others watching.

[Brambles]

Will H - 2016-04-02 11:28 AM

 

Thanks. I shall continue on my merry way doing as I always have by laying the cable up and down lengthwise at the side of the van, however odd it may seem to others watching.

Not odd at all, seems very sensible to me.

 

[Bulletguy]

Will H - 2016-04-02 9:32 AM

 

Derek,

 

Yes I did investigate Google. But why should I have to when highly educated persons (so called) cannot be bothered to write in simple English. I just don't get it !

 

I shall say no more

 

Will

 

Will, you mean CBA......can't be ar*ed. :D

 

I agree though. I see these acronyms and 'text speak' (txt spk?) on other forums and it really annoys me! Even worse, it crept into daily life at work and my employer used to thrive on it. Trendy buzz words such as "incentivise" or "duvet days" also drove me mad. >:-(

[Will H]

Bullet Guy,

 

Your emphasis on the 'cannot be bothered' is not how I expressed it for it gives an entirely different meaning to the phrase as I published it, it may be your view but was certainly not mine. My view was a general one, I suggest your was not.

 

Its like a threat with a gun without bullets to one that is loaded and ready to kill.

 

Its time this was closed.

 

Will

[colin]

English is a constantly evolving language, don't like it? hard luck :-D

I regularly read hundred year old text both technical and non technical and how we speak now is very different. Last year I was reading Darwin and for the first few chapters had to reread several passages to understand it.

[Bulletguy]

Will H - 2016-04-02 2:20 PM

 

Bullet Guy,

 

Your emphasis on the 'cannot be bothered' is not how I expressed it for it gives an entirely different meaning to the phrase as I published it, it may be your view but was certainly not mine. My view was a general one, I suggest your was not.

 

Its like a threat with a gun without bullets to one that is loaded and ready to kill.

 

Its time this was closed.

 

Will

 

Blimey............take a chill pill Will.

 

Even emoticons are lost on you and any humour is just wasted.

[Brabander]

I would like to add my pennies worth.

I happily leave my 2.5mm2 cable wound on the drum for the simple reason that I never use the camp site's electricity for anything other than charging my batteries and supplying power to my 12V MH circuit. The current drawn is therefore unlikely to be ever approach 5 Amp at 230V.

2.5mm cross section PVC insulated cable is rated at around 27 Amp. Even if such a cable is installed in conduit within an insulated wall (ie very little heat dissipation) it is still rated at 20 Amp.

The problem with long cables on drums is that any heat generated is mostly dissipated to heat the adjacent cable thus creating a vicious circle.

Therefore, if you intend to use the common 13 Amp UK camp site power supplies to the full for cooking, boiling and space heating you are well advised to unwind long cables from the drum.

Another consideration is the voltage drop in long cables. This can be considerable and this can result in a substantial increase in the current drawn through the cable.

For example if your load is 13 Amp the voltage drop in a 40m long 2.5mm2 cable could be as much as 10V. If in addition the camp site is a long way from a utility transformer the voltage at the camp site may well be at the low end of the supply tolerance band. Suddenly a 3kW load may well generate a current in your cable of perhaps as much as 14 Amp!

As others have already pointed out as the cable heats up the resistance increases and the voltage drop also increases, back to the famous vicious circle.

 

On most continental camping sites the current available tends to be limited to 5 Amp and sometimes even 3 Amp. The voltage is also often around 220V ie the power available may be only 1kW or less!

Because of this you will see a lot of partially wound cable reels!

 

I have 3 lengths of cable in my motorhome. A large reel with 40m of 2.5mm2. A short length of around 5m loosely wound using the shoulder/elbow method and a very short length of a couple of meters.

I will use these short lengths in preference to the reel whenever I can.

Unreeling and reeling up 40m of cable every day is only for those who enjoy self punishment.