Static Caravan Supply

30 Apr 2012
Reaction score
United Kingdom
Hi there folks,

I've got a static holiday caravan which keeps tripping the farmers distribution CU when too much power is drawn (ie 2kw fan heater along with other standing current draws like fridge, lights etc) on examining the van CU it's got 45A breaker ELCB, 32A power & 6A lighting mcbs, his circuit is a 16A mcb and is over 30m away - similar for all the other vans on site.

I would like to change the 32A for something lower so only the van power itself trips (& leaves the lighting on) do they make a 20A version that I could persuade the farmer to change to, then I could put a 16A in the van, or is there something else semi adjustable I could fit in the van?

I've tried putting wattage labels on all the plugs & a couple of notices up but people will ignore them. Incoming is 20/15A armoured by the look, sorry I haven't got any photos as its in the lakes.

Thanks in anticipation
Sponsored Links
If it is the ELCB (RCD) which is tripping, this will be because of a fault, either in the circuits or an appliance, and not because of overloading.

You need an electrician to find and rectify it.
The farmer would be ill-advised and may be breaking the terms of his licence to change his breaker capacity; it's not just the carrying capacity of the cable to your van but the balance/power calcs etc.
The suggestion would be to put a 10A MCB in your van for the sockets and change the heater to 1Kw.
Sponsored Links
We would need to know the cable size to the van and the cable size feeding the submain of the farmers, along with the fuse rating for this submain (assuming it is one). Only then could we calculate to determine what size breaker could be fitted.

If you are not paying for the electric per unit, it can be fairly typical to limit you using an MCB. Archaic.
Even if you for a 20A MCB instead of your 32A it will still be able to draw more than 16A so wont help you there, you need to reduce your energy consumption, you could get some emergency lights fitted so your not in the dark when it trips.
I have a touring caravan, same issue, as I use some low ampage sites, some as low as 6A.
I bought an energy monitor, same as you use in your house, mounted the display in an easy to see location, a simple, passive way to monitor your energy consumption.
you could change the 32A for a 10A most tourers have a 10A for sockets, and a 6A for other stuff, fridge, water heater etc.
the biggest cause of trips I have is forgetting to turn the heating off when using the kettle.
viewer said:
The suggestion would be to put a 10A MCB in your van for the sockets --


timtheenchanter said:
you could change the 32A for a 10A

That is the best answer. There's no easy way around the fact that you can only have 16 amps and you don't want all your lights going out when you switch the kettle on. With a 10 amp breaker in there, the worst that will happen is that you'll miss five minutes of TV when you switch on the kettle and the heater at the same time. :oops: :oops: :oops:
Space cat - why are you so incredibly embarrassed by your reply?

Surely it would have been better not to post it if you are that ashamed?
Many years ago I was working on the building of Sizewell Power Station and I want sent to modify the supplies to the static caravans.

I was told at that time there had to be a 32A supply to statics but for touring vans there were no rules and the site owner could use a 5A supply.

I have not been able to find these rules and it may have been one of the old wives tales that do the rounds.

However static and touring do have different rules although we may call them caravans they are mobile homes and as a result things like ban on TN-C-S supply does not always apply to a mobile home.

I think the way it is sighted has a lot to do with what the rules are? Problem is with internet it is very easy to end up reading USA rules but it's all to do with if it's classed as a building or not as far as I can tell. Which is something to do with size and base where the unit is too big to be towed by a car then it's not classed as a caravan.

As to discrimination that has long been a problem and I had a very heated argument with my boss when I feed the 6A MCB for lights from the 16A MCB for sockets so limiting total to 16A.

The problem is a consumer unit is a type tested unit and one in theroy is not allowed to change it from manufactures design.

However the twin pole RCBO is very similar in size to a RCD and one could likely fit a 20A or 25A RCBO to replace the RCD so the total supply is limited. Although likely it will not strictly comply with regulations.

Motor overloads come with variable setting so one could set them at odd figures like 28A but again strictly unless you are an electrician they should not be used.

I had some odd system with my caravan where the water heater was wired from the air-conditioning terminals of the thermostat for the heater so water could only heat up when heater was not working.

My son with a narrow boat with a 4A supply used large batteries a 3 stage charger and an inverter to get around the low supply. Not ideal but it did work.

In my caravan the fan heater was altered to run at 500W and 1kW and the element in water heater was swapped from 3kW to 1kW all helped in stopping the MCB from tripping.

708.553.1.10 The current rating of socket-outlets shall be not less than 16 A. Socket-outlets of higher current ratings shall be provided where greater demands are envisaged.

Sounds great but in reality it depends on the supply in the first place and with touring vans it was traditional to have a 5A supply which was really only to run items like the TV lights were gas, so was fridge, and no one would consider using a standard electric kettle. There were special 5A versions designed for the 5A supply. In many cases it would have required a complete re-wire of the field to have up-graded including new step down transformer supplying the site.

I would think the easy way is to replace the fan heater with a proper Carver heater running off the gas and remove electric kettles and let them use the stove to boil water on.
Well, thanks everybody for your information and suggestions, it looks like I'll have to reduce the heater wattage (which I'd bought specially) & fit a 10A breaker.

Iv'e also got some LED & low wattage bulbs to install/change over, so hopefully that will help too.

Thanks again folks for the ideas.
For my caravan I rewired the fan heater. The two elements were put in series rather than parallel and the selector switch shorted out one element so instead of 1kW or 2kW I got 0.5kW or 1kW and in the main the 0.5kW was enough to heat the 16' tourer I lived in.

I did not like using a fan heater as if the volt drop was too high there was a slim chance that the fan motor would not run. In which case one prays the thermal fuse will do it's job. However the oil filed radiator was just too big in such a small van.

The problem is once one alters the design of any equipment one has to realise any insurer may refuse to pay out should it fail. So if you copied what I did and get it wrong then should the caravan burn down it's your loss.

Not an easy call. As we all know what ever the regulations say the site has a limited supply and can only give out what it receives. So I would look at Carver heaters to replace the electric one.
fortunately this year Easter was quiet and relatively warm. In previous years we have had up to 4 or 5 local caravan sites blowing main or even substation fuses with the heating loads.
It got to the point with one that they were one fuse operation away from a permanent disconnection due to them affecting other customers
However the oil filed radiator was just too big in such a small van.
What about those oil-filled tubular heaters they sell for greenhouses?
No longer use a caravan so not an issue now. However at the time found the tubular heaters were not oil filled. Just a heater in a tube. I was looking for two features.
1) The oil stays hot so it does not cool down too quickly when thermostat turns off.
2) Maximum temperature limited so could not get too hot.

The fan heater was small and that was an advantage but the voltage was very variable dropping to below 200 volts at times and I worried about the fan not starting due to volt drop and as a result it overheating. Had it happen with one fan heater in an office block and it needed fire brigade with breathing apparatus to put out the fire. Only damage to building was scorch mark on floor the fumes were from the fan heater its self.

There is a thermal fuse which should blow if fan fails but with the one in the office it was positioned to warm someone and not flat on the floor so fuse did not rupture in time.

As a result I consider fan heaters are for attended operation only. I would not walk away and leave one running. Even just for lunch.

I did have a gas heater but it was old type without a flue so caravan got damp using it. The modern types vent under the van with a balanced flue so don't get the van damp. However they cost a lot more than simple fan heater.

We were surprised at caravan prices. The fully winterised caravan of exactly same design as the summer holiday version cost twice the price. I had considered a static van but when the job finished the site would lose their all year round licence and revert to summer only so I would have lost half the value as no one would want a second hand caravan costing more than a new one for summer use.

The summer vans were really hard to keep warm. They just did not have the insulation fitted to all year round vans. So I used a touring van which since smaller was easier to heat.

Gas was a problem the fridge alone could empty a bottle in three weeks. So there was a general move to using as much electric as we could. Microwave cooking, deep fat fryers, and sandwich toasters were all the rage plus low wattage kettles.

I fitted a 80A moulded breaker to stop the 100A fuse from blowing at the distribution point the site had a split phase 100A supply. With around 100 caravans half being used through the winter by Sizewell workers.

The big problem was everyone wanted more power and all sorts of tricks were done to increase what they could draw. Scraping the 1 of the 16A MCB so it looked like a 6A and also messing with calibration screws on 6A ones. The owner had to go around with a fan heater 1 and 2 Kw testing to see where people had fiddled the MCB to get more power. People did not seem to mind live working how no one was killed I don't know. At that time no RCD's on the supply. Today one would not be allowed to supply caravans like they were then. Often just a box in centre of pitch put in a bag when no van on the pitch when van in place the van protected box from rain.

No one complained caravans were a cheap way to live on a building site.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links