Watts v amps?

[WinnieSophie]

Evening all.
Am I right in thinking that (with trauma ultraheat), if a campsite electrical connection is at least 10 amp then I can safely have the thermostat at 2000w? What about 6amp,can I only have it at 500w?
Bit confused.
I gather at UK sites it will be 2000w anyway??
Going on a short trial run to Suffolk on Monday, before crossing the Channel mid May, so need to know in case I trip all the fuses!!
Thanks.
Cath
Mean truma, I've got the trauma :blink:

 

[bertieboy1]

Dear Trauma,here's the truma,
Site don't rate their electrical supplies in Watts,they are rated in amps.
For ac electrical heating you can easily find out what the current will be by dividing the Watts by the voltage.
eg, for 2000W divide Watts by voltage - 2000/230 = 8.695 amps..As long as your load (in amps)is less than the rated supply you will be OK.

 

[WinnieSophie]

Thanks, think I've got it.

 

[Hutch]

Cath, it's very easy to overload the caravan power supply, eg, you have the heater on in the morning, because its nippy outside, maybe you have used the hot water in the caravan and that's reheating, the tV on to see the news and your using an electric kettle, click it all goes off, as you have suddenly drawn to many amps for the, say 10 amp power from the campsite power.
In France it is common on some sites to only have 6 amp power. You just have to be carefull.

 

[WinnieSophie]

Thanks hutch, think I was over complicating maybe. Will just be careful then how much I'm using at any one time.
Cath

 

[Dustydog]

Cath
The attached from The Caravan Club will you appreciate how may amps each item uses.

https://www.caravanclub.co.uk/media/1026258/hookinguptothemains.pdf

 

[WinnieSophie]

Thank you, that's very useful.

 

[RayS]

Some microwave ovens take more current owhen switching on than they do when running and you may cause a trip by using the microwave when you have heating etc switched on as well.

Suggest you make a card showing the amps taken by each appliance or device by dividing the watts shown for each device ( found on the duty plate or from the instruction book) by 230 volts ( ( in UK) and then , given the amps available at each site, you can work out what combinations are within this figure. Don’r Forget to allow for the fridge and the battery charger which is built in to the caravan electrical system.
If you take the caravan to Europe be aware that many sites offer only 6 amps and often at lower than UK voltage typically down to 210 or less in Spain. This increases the amps taken slightly but, for example you can only use the Truma Combi 6 system on the Electric 1 setting.
Also check whether the site supply breaker can be reset by you or whether it has to be done by the warden. If by you, switch off heating oven etc before attempting to reset.
If in doubt ask another camper, we’re a pretty friendly lot and happy to share such information

 

[ProfJohnL]

Some microwave ovens take more current owhen switching on than they do when running and you may cause a trip by using the microwave when you have heating etc switched on as well.

Suggest you make a card showing the amps taken by each appliance or device by dividing the watts shown for each device ( found on the duty plate or from the instruction book) by 230 volts ( ( in UK) and then , given the amps available at each site, you can work out what combinations are within this figure. Don’r Forget to allow for the fridge and the battery charger which is built in to the caravan electrical system.
If you take the caravan to Europe be aware that many sites offer only 6 amps and often at lower than UK voltage typically down to 210 or less in Spain. This increases the amps taken slightly but, for example you can only use the Truma Combi 6 system on the Electric 1 setting.
Also check whether the site supply breaker can be reset by you or whether it has to be done by the warden. If by you, switch off heating oven etc before attempting to reset.
If in doubt ask another camper, we’re a pretty friendly lot and happy to share such information

Sorry Ray,

The vast majority of the electric power in caravans goes into resistive heating elements, and motors, a reduction in Voltage has a corresponding reduction in the current or motor speed.

 

[Grey13]

Get someone to fit an amp meter in your van. Very simple and no power wiring interruption. Something like this sending the signal to a small panel mount current indicator. https://uk.rs-online.com/mobile/p/current-transducers/0198835/

 

[ProfJohnL]

Get someone to fit an amp meter in your van. Very simple and no power wiring interruption. Something like this sending the signal to a small panel mount current indicator. https://uk.rs-online.com/mobile/p/current-transducers/0198835/

The item you have suggested will only measure AC current, (see the data sheet) however there are non invasive products that do measure DC, but they are usually more expensive and need some form of power to operate. But either type is only the measurement probe the still need some form of display to make them human readable.

 

[Icaru5]

It is AC that the OP is interested in monitoring though Prof, hence probably the reason why Grey suggested that particular item.

@WinnieSophie - Many modern vans already have comprehensive current monitoring (both AC and DC) and current limiting as part of their integrated control system.

Out of curiosity, what make, model and year is your van ?

 

[ProfJohnL]

Thank you Icaru5,

I had forgotten the content of the thread was about 230V systems.

For private reasons I do not currently have a caravan.

 

[ericmark]

Technically watts = Volt x Amps x Power factor correction and with a heater the power factor is 1 so for real life we can consider that VA = Watts.

Now our systems are normally limited by miniature circuit breakers (MCB) which is two devices in one, so a B16 MCB will trip at between 3 and 5 times the rated current using the magnetic part of the trip, and this will happen in around 0.01 seconds. However the thermal part of the trip takes a lot longer, there are charts, but at 16A it should never trip and at 20A it will likely take at least 1/2 an hour, so if you have a thermostat switching off/on every 15 minutes then the MCB is looking at the average current rather than spot current.

So with a room heated set to 2000W (8.7 amp) it will normally take same average current as set to 500W (2.2 amp) once caravan is up to temperature. Where the problem lies is a kettle, water heater, room heater and battery charger all being switched on together so 2.7kW + 2KW + 0.75KW + 0.25kW all together = 5.7kW or 25A which will not reduce fast enough to stop the MCB tripping,

you have around 1000 seconds or 16 minutes and your just on the edge as to if kettle knocks off or the MCB trips first.

If the MCB is already warm it will take less time, so using the room heater at 500W means it is less likely to trip before the kettle boils at 18.3 amp it is still over 16A but time is more like 10,000 seconds or just under 3 hours, so kettle will have boiled and knocked off well before then.

Whole idea of MCB thermal part is to stop cables melting, so cables also take time to heat up, so as long as the MCB trips before cable melts there is no problem.

 

[Hutch]

Ericmark , thanks for a very long winded Expanation of how MCB's work , but you will only make WinnieSophie totally confused. The likes of others will find your post lovely prior to going to sleep.
PS, thats why we totally unwind the EHU cable so that we don't melt the cable or make compasses read wrongly.

 

[WinnieSophie]

Hi, it's an Abbey Expression 500 and it's a 2005 model
Cath

 

[Parksy]

Ericmark , thanks for a very long winded Expanation of how MCB's work , but you will only make WinnieSophie totally confused. The likes of others will find your post lovely prior to going to sleep.
PS, thats why we totally unwind the EHU cable so that we don't melt the cable or make compasses read wrongly.

Now now, play nicely Hutch
I take your point but if there's something that is of interest to other members they will read it.
If an item is too technical or of minimal interest to others they will simply scroll past to find something that they can relate to.
How do you know that Winnie Sophie isn't a nuclear physicist or a rocket scientist who enjoys caravanning? :lol:

 

[Grey13]

Prof. Time for glasses old chap. Topic is clearly 240 vac related and CT suggested ...sends a signal to a current indicator mounted in the van. As mentionef in my op. Anyway most on here will not be able to instsll such a system and would need a sparky to install.

 

[bertieboy1]

Parksy,
If Winnie was employed as what you mentioned she wouldn't have asked the question.

 

[ProfJohnL]

Prof. Time for glasses old chap. Topic is clearly 240 vac related and CT suggested ...sends a signal to a current indicator mounted in the van. As mentionef in my op. Anyway most on here will not be able to instsll such a system and would need a sparky to install.

Heres my pedantic bit....We now officailly use 230VAC in the UK.... However, as teh CT you have suggested makes no physical connection to the mains wiring, it does not need a sparky. But care must be taken to fully insulate all the wiring between teh CT and meter.

 

[Hutch]

Ericmark , thanks for a very long winded Expanation of how MCB's work , but you will only make WinnieSophie totally confused. The likes of others will find your post lovely prior to going to sleep.
PS, thats why we totally unwind the EHU cable so that we don't melt the cable or make compasses read wrongly.

Now now, play nicely Hutch
I take your point but if there's something that is of interest to other members they will read it.
If an item is too technical or of minimal interest to others they will simply scroll past to find something that they can relate to.
How do you know that Winnie Sophie isn't a nuclear physicist or a rocket scientist who enjoys caravanning? :lol:

Parksey because Cath , has asked a simple question , and not a requested a reply about MCB's and thermal problems has mentioned she has, a single wheel caravan. Read her lovely posts, just trying to help the lass out.

. EM. Tends to over complicate posts., seen them on other sites.

 

[Parksy]

Ericmark , thanks for a very long winded Expanation of how MCB's work , but you will only make WinnieSophie totally confused. The likes of others will find your post lovely prior to going to sleep.
PS, thats why we totally unwind the EHU cable so that we don't melt the cable or make compasses read wrongly.

Now now, play nicely Hutch
I take your point but if there's something that is of interest to other members they will read it.
If an item is too technical or of minimal interest to others they will simply scroll past to find something that they can relate to.
How do you know that Winnie Sophie isn't a nuclear physicist or a rocket scientist who enjoys caravanning? :lol:

Parksey because Cath , has asked a simple question , and not a requested a reply about MCB's and thermal problems has mentioned she has, a single wheel caravan. Read her lovely posts, just trying to help the lass out.

. EM. Tends to over complicate posts., seen them on other sites.

Chill out Hutch, I was only kidding, but I knew that you'd bite
Sorry, couldn't resist :lol:
Bad Parksy! :evil:

 

[Grey13]

Prof as always thinking intricate lrgal details. However my comment stands the average layman/ woman will not be able to get their heads around taking a 0 to 10 v dc signal and inputting it to an indicator then scale it to read correctly. Let alone figure out if it needs loop powering. My business sells these type of things and trust me even most electricians not familiar with instrumentation do not understand. What next Prof.

 

[Grey13]

General comment. Here we have an average caravaner asking about pitch supplies and how to ensure when she turns on the kettle it does not trip. Let me see....she hss been given more theory and superfluous bumph she does not need let alone actually understand. How about someone simply listing what each appliance uses then explaining that when adding the ones thst are on it must not ecceed the pitch supply trip value (10, 13, 15 16 amps). I am sure that will surfice

 

[Danddandy]

I found ericmark's explanation interesting and informative. Now I know why my kettle sometimes trips the power and sometimes doesn't .