Mains Hook Up Cable

[Buffers]

I have seen mains hook up cable at 1.6mm which I understand is suitable for 10amp supply. I have seen 2.5mm which is good for 16amp supply.

Do you need to go above 1.6 mm

 

[Raywood]

Site supplies vary from 6 amps to 16 amps depending on age but any hook ups fitted now will be 16. The 10 amp cable will limit the sites you can visit so 16 should be a better long term buy whatever your short term plans. Do not use a 10 amp cable on a 16 amp hook up.

 

[ProfJohnL]

I have seen mains hook up cable at 1.6mm which I understand is suitable for 10amp supply. I have seen 2.5mm which is good for 16amp supply.

Do you need to go above 1.6 mm

Simple answer is YES.
The blue connectors on the EHU are rated for 16A, and the cable between them must also be able to carry that current with out danger. Its as simple as that so it should be a minimum of 2.5mm2 csa per conductor.

 

[chrisn7]

The outer orange insulation layer seems vary in diameter - is this a function of the conductor size within, or are the thinner ones just cheaper but same conductor size?

 

[ProfJohnL]

In general yes, the smaller the csa, will means the overall cable diameter is likely to be smaller. But that is not guaranteed or the way to select and buy a cables. You should be looking for the csa size on the description of the cable and that it complies with BS7671

 

[WoodlandsCamper]

A quick check on Towsure website shows they sell 2 kinds of hook-up cable, both rated at 16A with 16A connectors

Product code M45 - 1.5 mm core (quote - "For connecting caravan electrics to any UK 240 volt site hookup")

Product code M4525 - 2.5 mm core (stated as - "heavy duty")

I have 2x EHU cables, one kept in the van and one at home. The one at home is stamped:- "H05VV-F 3G2.5 to BS6500" so I'm guessing it has 3 cores each 2.5 mm[sup]2[/sup] cross sectional area. I will check the one in the van next time I go to storage.

If weight is anything to go by (thicker conductors and thicker insulation) then my 25m EHU lead weighs 4.5kg.

 

[ProfJohnL]

Ok I have just refreshed my knowledge on cables. Apparently BS6500:2000 Table 27 and BS EN 50525-2-11 Table 2 do rate 1.5csa pvc pvc 3 core for 16A. So 1.6csa cable should be fine for hook up. But 2.5 is still my recommendation.

It may seem strange to discuss the efficiency of a cable, but as identified in a previous thread EHU cables along with all normal domestic cables do have an inherent resistance per unit length. The resistance is inversely proportional to the csa of the cable, so the bigger (diameter) the cable the smaller the resistance will be. By the same effect the longer a cable is the bigger resistance the cable will exhibit.

So when ever a current flows through a conductor its resistance will sap some of the power and convert it to heat. So the lower the resistance the less power will be lost.

It is this power loss in a cable that leads us to the reason why its important to fully unroll EHU cables, because normally an unwound cable exposes the whole length of the cable so the small amount of heat generated can easily dissipate to the environment, but if a cable is wound then the heat cannot dissipate and it will build up and may cause the insulation to fail.

Just by way of comparison a 25M long 1.5 csa and 2.5cdsa EHU's

Resistance (1.5 csa) 13.3 (2.5csa) 7.98 Oms per Km per conductor
Don't forget that to complete the mains circuit you have live and neutral conductors so that doubles the length of current carrying conductor so we are looking at a 50M length of working conductor.

so the resistance per EHU will be given by

50x Resistance/1000 Ohms

for 1.5csa that is 50x13.3/1000 = 0.665 Ohms
for 2.5csa that is 50x7.98/1000 = 0.399 Ohms

These values may not seem very big but the heating effect is governed by current x the current x Resistance so at 16A or ( I squared R)

for 1.5csa 16x16x0.665 = 170.24 Watts
for 2.5csa 16x16x0.399 = 102.144 Watts

So to minimise these full power losses in the cable, it is better go fir the 2.5csa.

 

[DrZhivago]

The 10 amp cable will limit the sites you can visit .... Do not use a 10 amp cable on a 16 amp hook up.

That brought me up short. Just because a site offers 16A does not mean you have to take 16A. Not knowing much about caravan electrics (but I do know a bit about electrics generally), I would have thought that you should not be relying on the site's hook-up point circuit breaker to protect your cable.

If you have a cable that can only take 10 A then both : (1) the maximum current the van can draw (ie with everything turned on) should be less than 10A, and (2) the van should have its own 10A breaker or fuse.

The above statement could be given with 16A instead of 10A, or any other amperage in fact.

 

[Raywood]

The problem with using a 10 amp rated cable on a 16 amp site is you could accidentally overload it. If the caravan has electric water and internal heating and you have them on, the kettle, the fridge , and TV and anything else you are likely to exceed the cables rating. The Truma in our caravan can draw 9 amps on its higher setting so it takes very little if that is on to exceed 10 amps.
It sounds like a cheap bit of gear which I would not risk.

 

[ProfJohnL]

The problem with using a 10 amp rated cable on a 16 amp site is you could accidentally overload it. If the caravan has electric water and internal heating and you have them on, the kettle, the fridge , and TV and anything else you are likely to exceed the cables rating. The Truma in our caravan can draw 9 amps on its higher setting so it takes very little if that is on to exceed 10 amps.
It sounds like a cheap bit of gear which I would not risk.

Hello Ray,

What you write is correct, but I think the thread has been miss steered by the OP who told us he thought the 1.5csa cable was only rated to 10A. As I pointed out in my earleir post, the IEEE through British standards actually rate a 1.5csa for 16A.

Dr Zivargo has also correctly pointed out that if you only had a 10A cable it should be protected so it cant exceed 10A, but that is impractical for caravans which have the CEEform 16A connectors, and thus should only be used with cables with a minimum rating of 16A.

Any company selling a 10A cable fitted with 16A connectors at either end should be reported to trading standards for the very reasons that Ray points out, but I suspect that is not actually the case in this instance.

 

[KeefySher]

Applying simple sums is to my mind a good way to ensure piece of mind rather than elf and safe tea fears.

6A supply gives you capacity to use appliances up to 1320W (1.32kW).
10A supply gives you capacity to use appliances up to 2200W (2.2kW).
16A supply gives you capacity to use appliances up to 3520W (3.52kW)

The hook up cable should reflect the use, so 2.5mm2 will cover the higher loads possible if you consider caravans can have 3kW water heating capability.

If on a 6A supply don't leave the onboard water heater switched on, or at the same time as a low wattage kettle, hotplate, or hair dryer for example.

A domestic kettle and fan heater is often 3.5kW so leave them at home.

Pedants will doubtless comment on the above figures but based on supply voltage in the range of 220-240V, distance of cabling in a campsite setting, it is doubtful that 240 is actually possible.

 

[ProfJohnL]

Applying simple sums is to my mind a good way to ensure piece of mind rather than elf and safe tea fears.

Why the constant mockery of health & safety related posts? You are happy enough to take advantage of the safety afforded when its applied to restaurants, hospitals, the roads, cranes lifts, and virtually all other aspects of living in a society, etc, so why is it necessary to be so childish when its related to caravans?

 

[KeefySher]

Applying simple sums is to my mind a good way to ensure piece of mind rather than elf and safe tea fears.

Why the constant mockery of health & safety related posts? You are happy enough to take advantage of the safety afforded when its applied to restaurants, hospitals, the roads, cranes lifts, and virtually all other aspects of living in a society, etc, so why is it necessary to be so childish when its related to caravans?

I apply elf and safe tea to every occasion it is used as an argument to deminish people taking personal responsibility for their actions and the effects of those actions on others. If a salesman were to attempt to sell me a caravan, or a car or anything based on H&S, I'd walk away. An industry of elf and safe tea has grown up that is to my mind teaching people that systems, processes, technology etc will keep them safe; it does not. That the biggest cause of accidents and incidents are human factors often far removed from the event is not comprehended by the blind followers of H&S.

My challenge to you is tell me of a safety related incident that was not human factors related, often at arms length.
A few headline events to jog your mind, all root causal HF:
Piper Alpha.
Challenger.
Concord.
Hatfield.
Deepwater Horizon.

Are restaurants safer? Or are the additives in our food to enable it to travel in time and distance outwith it's natural cycle combined with resistance to and effects of chemicals in the food chain root causes of why there are elf and safe tea rules and regulations created to treat the effects not the cause?

Hospitals safer? Why are there more adverse effects since the banishment of cleaning regimes undertaken regularly by nursing staff and using bleach?

Roads safer? The advancement in surface materials, tyre performance, braking systems, suspension systems have not kept equilibrium with the development of the human brain and the medication given to drivers that slow brain function and reactions to treat conditions created by food additives and processing. A lot of academic research has been suppressed in this area.

Cranes safer? Probably are in terms of load sensors and interlocking, but not due to lifting plans and method statements which are a post incident tool for lawyers to earn fees.

Are societies safer that have elf and safe tea cultures? I'm not convinced from my global experience in truly intrinsically safety critical environments. My personal experience of fatalities and serious injuries, incidents and near misses is that of multiples (x10's) more here in the UK alone than in total in developing countries, or overseas per ce. I put that poor performance at the door of the elf and safe tea culture that has grown here.

If having an open debate and expressing educated facts and opinion is childish, the utopian society you paint in word is not one I'd be happy in tbh. Black humour is a proven tool in dealing with the effects of trauma, often associated with accidents and incidents

I'd like to understand how my simple sums applied to the hook up cable debate are in your mind, childish?

 

[Parksy]

I have seen mains hook up cable at 1.6mm which I understand is suitable for 10amp supply. I have seen 2.5mm which is good for 16amp supply.

Do you need to go above 1.6 mm

Above is the original query which ought to generate relatively simple straightforward replies.
Instead this thread is meandering down the well worn path which involves disputed facts, personal argument and insinuation.
Can we at least try to stick to the subject of the discussion just for once please?

 

[Raywood]

It has got amazingly technical when the simple answer for me is that if you have 16 amps available it makes no sense to use a cable rated at only 10 amps..

 

[WoodlandsCamper]

Yes, but the OP implied having a 10 amp cable fitted with 16 amp connectors - DANGEROUS. It turns out that 1.5 mm csa cable is rated at 16 amp and not 10 amp as previously stated.

 

[ProfJohnL]

I must appologise to KeefySher for my post which I realise was incomplete.

I was not disputing his breakdown of power usage in caravans, and in reality he is probably right about the the supply voltage being depressed at the end of a large caravan sites cabling.

What I do object to is the belittling of posters who correctly refer to the needs to comply with regulatory requirements. As a member of a 'free' society we do have a degree of choice in some matters but in others society has found it necessary to limit some activities or to ensure they are carried out with due care and attention to protect individuals and the rest of the public.Our freedoms come with some responsibilities and H&S is one of them.

We have all benefitted from issues of Health & Safety even though we may not realise it. Health & Safety would not be necessary if everyone acted sensibly, but sadly that is not the case.

No one has claimed that H&S is 100% perfect, but it is far preferable to the anarchy that would ensue it it were not present.

 

[WoodlandsCamper]

Perhaps Buffers may like to comment on the replies to his thread? :huh: