EHU frustration

Hi all,

Its been a while since I have been on here but have been making the most of my little spare time and taking Holly "harmony" out and about after the initial problems I had with the zig unit and battery charging etc which i sorted out all has been great up untill this last trip.
Plugged into the EHU on site and carried on setting up the awning etc as usual, went to swith electric kettle on to realise all the power had tripped. checked in the van and our RCD was fine so went to the bollard, this had tripped. reset and 30 secconds later the same happened but this time the van 240v socket circuit rcd tripped before the bollard. after about an hour of shall we say rather colourful language I got the electric to stay on but only by leaving the 240 socket rcd switched off and just running the one that powers fridge/waterheater/battery charger because as soon as I switched the sockets back on the whole lot went.

Now I fully understand the whole overloading of site electrics and generally only try and use about 1600w at any one time HOWEVER whats confusing me is that both of the 240 sockets were switched off and nothing was plugged into them so nothing in theory should of made it trip out was it just an overly sensitive EHU bollard or could it be something more serious? It seems to be fine plugged into the mains at home but obviously if there is potentially something wrong with the mains sockets or RCD I would like to sort asap especially as will need electric to warm the awning up now its dropping colder.

Sorry for the essay but i like to give lots of information :-D

Cheers in advance

Neil

Hi Neil,

If you are using the same lead at home, and everything is working Ok the chances are that it was the site electrics that were at fault.

Although gremlins do some times appear if it had been Ok previously, and is Ok now Murphys Law ( sorry Murphy ) would dictate that it was the particular situation that caused the problem, the only difference being the site!

Best thing you can do other than have all the electrics checked is visit another site, and see what happens.

Stuart

stuartneale1 wrote:Hi Neil,

If you are using the same lead at home, and everything is working Ok the chances are that it was the site electrics that were at fault.

Although gremlins do some times appear if it had been Ok previously, and is Ok now Murphys Law ( sorry Murphy ) would dictate that it was the particular situation that caused the problem, the only difference being the site!

Best thing you can do other than have all the electrics checked is visit another site, and see what happens.

Stuart

Thanks stuart, Thats kinda what I was thinking but its going to be a week or so before im away again so looks like i had better sort some gas heating for the awning as a "just in case" thankfully i always travel with the gas kettle on board so never short of a brew

Hi there,

Two things to look at:

1. Was the water heater switched on? It pulls a fair amount of power and can trip an RCD quite easily, especially if there is also something else plugged in or even if the battery charger is running flat out.

2. We use a really heavy duty 20m cable because a long light duty cable will increase the amount of amps being pulled.

The other thing is that the amount of power promised by the camp-site is very often based more on hope than reality.

Hope this helps.

Best regards,

Dutto wrote:Hi there,

Two things to look at:

1. Was the water heater switched on? It pulls a fair amount of power and can trip an RCD quite easily, especially if there is also something else plugged in or even if the battery charger is running flat out.

2. We use a really heavy duty 20m cable because a long light duty cable will increase the amount of amps being pulled.

The other thing is that the amount of power promised by the camp-site is very often based more on hope than reality.

Hope this helps.

Best regards,

Hi Dutto,

Yes had the water heater on, the fridge on and the battery charger all running on RCD no2. I did switch the water heater off as from memory it pulls about 800 watt but even with that off the moment i flipped the RCD no1 for the sockets (even with them switched off and nothing plugged in) it tripped again after about 30 seconds :-( as you can imagine very frustrating, especially as the 2 other MH's on our part of the field were sat with there satelite systems watching xfactor lol

Regards

Neil

Neil,

If it was me and it stopped me having to watch "X-Factor" I would keep everything just as it is! ("Deal or No Deal" is bad enough!)

OK, going back to the problem:

1. It is quite common for one RCD to trip another when they are in series. (I had this problem with a 35amp supply to a garage. I occasionally tripped it in winter with heaters and a welder and it would trip the main RCD supplied by Scottish Hydro!) This means that if the one on the site tripped first then it could also trip the one in the caravan; and vice versa.

2. I noticed that you state that you need the 240V supply to put heat in the awning, and that everything worked OK if the socket RCD was left tripped. This indicates that there may be a bad connection on the socket circuit. If there is an outside socket the wiring to this one would be my very first "suspect".

Just to cheer you up I was once asked to share a free 3amp supply to my boat on the basis that the newcomer would only use it for fridge and charger.

First thing next morning bang goes the electricity. I walk the 75 metres to re-set the trip and returned to my boat; just in time for the newcomer to tell me it wasn't him and to hear my good lady shout that the electricity was off again.

On my THIRD walk back from the supply point I heard the familiar whirring of a hair-dryer running from the newcomers boat so I went back and disconnected his plug! The newcomer came out of his cabin as I walked back and we agreed that it was the right thing for me to have done!!

Best regards,

Ian

Dutto wrote:Neil,

If it was me and it stopped me having to watch "X-Factor" I would keep everything just as it is! ("Deal or No Deal" is bad enough!)

OK, going back to the problem:

1. It is quite common for one RCD to trip another when they are in series. (I had this problem with a 35amp supply to a garage. I occasionally tripped it in winter with heaters and a welder and it would trip the main RCD supplied by Scottish Hydro!) This means that if the one on the site tripped first then it could also trip the one in the caravan; and vice versa.

2. I noticed that you state that you need the 240V supply to put heat in the awning, and that everything worked OK if the socket RCD was left tripped. This indicates that there may be a bad connection on the socket circuit. If there is an outside socket the wiring to this one would be my very first "suspect".

Just to cheer you up I was once asked to share a free 3amp supply to my boat on the basis that the newcomer would only use it for fridge and charger.

First thing next morning bang goes the electricity. I walk the 75 metres to re-set the trip and returned to my boat; just in time for the newcomer to tell me it wasn't him and to hear my good lady shout that the electricity was off again.

On my THIRD walk back from the supply point I heard the familiar whirring of a hair-dryer running from the newcomers boat so I went back and disconnected his plug! The newcomer came out of his cabin as I walked back and we agreed that it was the right thing for me to have done!!

Best regards,

Ian

hahahah to be fair I kindof agree re Xfactor I have a small gas heater for the awning but travel with an oil filled rad as i dont like the bright hallogen heaters and the rad uses very low wattage compared to the heat output for a small awning (also safer than naked flames of gas)

I dont have an external socket on the van (tho i had thought of fitting one but no where suitable so scrapped that idea) so If i want to use awning electric i simply plug in to the factory fit socket above the side slide door. At this point tho nothing at all was switched on or plugged in to any of the sockets.

What your saying about the site RCD and van RCD makes sense as when i flipped the socket circuit it tripped both the van (sometimes the main rcd switch sometimes the socket one) and the bollard but not always, When i get a spare 5 min im going to undo teh sockets and just double check that there are no loose connections, although it could be as said just a very dodgy site supply (i hope so ) because as much as I have never been a fair weather camper its nice to get cosy on autimn evenings in me home from home :-)

Cheers

Neil

Neil,

I once had one of those "It must be the site because all I have on is my oil-heater." argument with a site-owner in France.

I had only paid for 5amps but I was so convincing that, rather than check his bollard in the pouring rain, the gentleman apologised profusely and moved my supply to a 10amp socket.

Ten minutes later I opened the cupboard under the sink and saw the red tell-tale light of the water heater!

I am proud to say that the very next morning I went and confessed to the site-owner before he got all his tools out to check his supply and even coughed up the extra €1!

Best regards and hope it was the site connection,

Ian

Dutto wrote:Neil,

I once had one of those "It must be the site because all I have on is my oil-heater." argument with a site-owner in France.

I had only paid for 5amps but I was so convincing that, rather than check his bollard in the pouring rain, the gentleman apologised profusely and moved my supply to a 10amp socket.

Ten minutes later I opened the cupboard under the sink and saw the red tell-tale light of the water heater!

I am proud to say that the very next morning I went and confessed to the site-owner before he got all his tools out to check his supply and even coughed up the extra €1!

Best regards and hope it was the site connection,

Ian

Thank god for honest happy campers eh :-) just sat n worked out the wattage re amps etc and if it was only a 5amp pitch (which wouldnt suprise me as they charged 10p for hot water in the toilet block) then i would of been very close if not over with just circuit 2 running (water heater/fridge/charger) so that could well be the answer :-)

mental note to ask about the amps when i book lol

cheers for the help :-)

Dutto wrote:
2. We use a really heavy duty 20m cable because a long light duty cable will increase the amount of amps being pulled.

Sorry Dutto but I have to disagree with that one.
A long light duty (i.e. thin) cable increases the resistance and leads to a voltage drop and less current on most types of load.
With the level of current usually drawn on site the effect is likely to be minimal unless the cable is really long.

I agree with all your other points though.

brodco wrote:

Dutto wrote:
2. We use a really heavy duty 20m cable because a long light duty cable will increase the amount of amps being pulled.

Sorry Dutto but I have to disagree with that one.
A long light duty (i.e. thin) cable increases the resistance and leads to a voltage drop and less current on most types of load.
With the level of current usually drawn on site the effect is likely to be minimal unless the cable is really long.

I agree with all your other points though.

I may be wrong but my logic is as follows:

If Amps = Watts divided by volts (which it does) and the normal supply of 240 volts drops due to a thin cable (which it does) then the Amps required to operate an appliance will rise because the Watts are fixed.

A 1,000 Watt electric fire at 240 Volts will pull 4.16 Amps. If the voltage drops to 200 Volts the same appliance will pull 5 Amps.

Your move.

Best regards,

Ian

Dutto wrote:
If Amps = Watts divided by volts (which it does) and the normal supply of 240 volts drops due to a thin cable (which it does) then the Amps required to operate an appliance will rise because the Watts are fixed.

A 1,000 Watt electric fire at 240 Volts will pull 4.16 Amps. If the voltage drops to 200 Volts the same appliance will pull 5 Amps.

Ahh but the watts are not fixed (I was careful to say on most types of load).

The thing that’s fixed(ish) about a heater is the resistance and when I say heater I include kettles, hairdryers, curling tongs etc - or any resistive load.

Since Current = Voltage / Resistance when the voltage drops so does the current.

The constant wattage theory will generally only apply to things with regulated power supplies such as TVs. I’ll admit that the current may go up a bit with this type of unit they tend to draw low current anyway so the increase is negligible.

Incidentally , I’ve just looked at the rating plate on my kettle. It says 220 to 240V 2520 to 3000W. more evidence for my assertion that the wattage isn’t fixed.

Next round!

Hi
We had a similar problem on our first trip last year (in a borrowed van),the power kept tripping. Eventually we unplugged the travelling electric kettle and everything worked. Plug in the kettle and before we could switch on power tripped. We stopped using the kettle and everything worked OK. On our first trip with our own van and using the same model of old travelling kettle the power tripped. We bought a new kettle and have had no more problems. Both these kettles worked fine when used at home.
Hope this helps.

Louise

Hi Louise.

Just love your logic. B r the maths ohms law and all that. Just get the kettle working and lets have a cuppa.

Cheers. Whisky.

The circuit breaker could be tripping for two reasons:

1) Too much power being used (the danger being that something could overheat and catch fire).

2) Faulty appliance (or wiring) causing some current to leak to earth (i.e. you could electrocute yourself if the leakage causes something to be 'live').

whisky wrote:Hi Louise.

Just love your logic. B r the maths ohms law and all that. Just get the kettle working and lets have a cuppa.

Cheers. Whisky.

Loved it



Ian and Brodco you may be able to tell us the square root of a banana, but you would probably have difficulty peeling it .


Only teasing Lads,


Andy

brodco wrote:

Dutto wrote:
If Amps = Watts divided by volts (which it does) and the normal supply of 240 volts drops due to a thin cable (which it does) then the Amps required to operate an appliance will rise because the Watts are fixed.

A 1,000 Watt electric fire at 240 Volts will pull 4.16 Amps. If the voltage drops to 200 Volts the same appliance will pull 5 Amps.

Ahh but the watts are not fixed (I was careful to say on most types of load).

The thing that’s fixed(ish) about a heater is the resistance and when I say heater I include kettles, hairdryers, curling tongs etc - or any resistive load.

Since Current = Voltage / Resistance when the voltage drops so does the current.

The constant wattage theory will generally only apply to things with regulated power supplies such as TVs. I’ll admit that the current may go up a bit with this type of unit they tend to draw low current anyway so the increase is negligible.

Incidentally , I’ve just looked at the rating plate on my kettle. It says 220 to 240V 2520 to 3000W. more evidence for my assertion that the wattage isn’t fixed.

Next round!

Loving this!

"............ when the voltage drops so does the current."

If you go to [You must be registered and logged in to see this link.] and feed in my example you will see that:

At 240 Volts a 1,000 Watt load will result in 4.1666 Amps and 57.6 Ohms resistance.

At 200 Volts a 1,000 Watt load will result in 5.00 Amps and 40 Ohms resistance.

If I maintain the 240 Volts but DROP the resistance to 40 Ohms resistance I get an INCREASE to 6 Amps AND an INCREASE to 1,440 Watts.

Whereas, if I DROP the Volts to 200 and RAISE the resistance to 57.6 Ohms I get a DECREASE to 3.57 Amps and a DECREASE to 694.4 Watts.

The key to the Formula used on the site I am using is that you only need TWO parameters to work out TWO OTHER parameters; and the TWO start parameters in my example were correct.

"It says 220 to 240V 2520 to 3000W. more evidence for my assertion that the wattage isn’t fixed."

Of course it isn't. The purpose of ANY Formula is that from two or more parameters another parameter can be calculated. In the example given:

o 220V at 2520 Watts gives 11.45 Amps and 19.2 Ohms.
o 240V at 3000 Watts gives 12.5 Amps and 19.2 Ohms.

In this case the resistance is fixed BUT THE AMPS THAT TRIP RCD'S CHANGE when the voltage changes!

Your move!

Best regards,

Ian

andygump wrote:..............

Ian and Brodco you may be able to tell us the square root of a banana, but you would probably have difficulty peeling it .

...............

Andy,

That is NOT funny!

I only found out two nights ago, by watching Caribbean Cooking on The Food Network, that I am supposed to peel plantains before cooking them!!

The ones on TV, gently fried in butter and oil, looked delicious; as opposed to the lumps of blackened mush that I have been fishing out of my curries for the last three years!

Best regards,

Ian

Peel bananas? No wonder I’ve always found them tough and chewy!
To business:
“Of course it isn't. The purpose of ANY Formula is that from two or more parameters another parameter can be calculated. In the example given:
o 220V at 2520 Watts gives 11.45 Amps and 19.2 Ohms.
o 240V at 3000 Watts gives 12.5 Amps and 19.2 Ohms”.

Ahh we agree on something excellent.

But look at what you’ve just worked out. 240v 12.5 amps 220volts 11.45amps – the current has dropped.
That’s my point. In your original example you’re assuming the load remains at 1000W when the voltage drops. It doesn’t because the resistance of the heater is nearly constant (we could go in to why that is if you like - oh eck).

“In this case the resistance is fixed BUT THE AMPS THAT TRIP RCD'S CHANGE when the voltage changes!”

Yes but I wasn’t arguing that the current didn’t change between using thick and thin cable. I was arguing that it didn’t go up when you use thin cable.

Seriously though I think we’re going way off topic. If we want to continue with this discussion I think we should open a new thread in the “Technical” section before we get kicked off by the moderators.

I’m kind of hoping you do. I love a good natured disagreement!

Don't be daft! You win!!

I knew I was going down in flames when I did the kettle on the website.

Best regards,

Ian

I am not going to get technical as I don't have the knowledge but in my experience here at Hendre Mynach Touring Park (10a system) when a customer complains they have no supply from the EHU (after we get the usual, it must be your bollard as it worked fine at home/ at the last place) I take my trusty test lamp (simply a bulk head light fixed to a EHU plug). 99% of the time the light illuminates immediately.

Then to help to try and sort the problem it is a trace through the electrics. I go and get one of our EHU leads, this often works suggesting it is their cable.

Or, go through the switching of things on to see what makes the RCD in the unit (caravan/ motorhome/ tent) trip out. Quite often it can be the water heater but sometimes something as simple as the kettle, especially rapid boil types.

Often, it is because something is on when the EHU is connected, whether it be a water heater or even just a light will cause them to trip.

Very often though, a lot of our problems arise after folks have set up and been there for a while and it is due to folks putting too much on at the same time. Microwave, heater, TV, playstation, then stick the kettle on.........PING! The abuse I get is very naughty as some folks think they should be able to use all the comforts from home in a field when on holiday

I can literally spend hours trying to help sort these problems out for people, even with no previous knowledge, just by process of elimination.

One such instance was a caravan whose 240v wouldn't switch on. Of course it was our supply at fault (he said, with a load of abuse) but after 40 minutes I suggested hooking up the car to caravan electrics back up. Starting the car, then go through the disconnect procedure slowly. Switch off engine, disconnect both cables, insert hook up........................IT WORKED!!!! I then had to spend a further 10 minutes listening to a load of suggesting that our system had somehow damaged his change over thingy............... and no thanks what so ever !!!!

Just thought I would give a brief view from the other side of the fence

Ian

Ian,

After living on a boat for eight years and in a motorhome for nearly a year we have a multitude of tales to tell and can appreciate very much what it must be like from your side of the fence.

How about:

1. The snotty sixteen-year old kid who unplugged our EHU so that he could charge his phone? (His father hit him before I could get there!)

2. The man who came along the quay with his EHU and in fifteen minutes tripped EVERY bollard? It was a "free" mooring and he was trying to run a self heating washing machine, deep-freeze, fridge and air-conditioner off it. We watched his progress and stopped him when he got to within 10 yards of where we were plugged in!

3. The lady who unplugged us because her EHU kept tripping and she wanted to "Test it on another bollard." In this case she was trying to run an oil-heater, a fan-heater, fridge etc plus 25 x 40 watt coloured lights strung out for Xmas!

I could go on and on and on!!

Best regards,

Yes with us living on a narrowboat for 8 years too, we had fun at jetties.................T'is funny how the next bollard along is the one to go checking out when theirs tripped out.

One night I too, spent ages going through my electrics cupboard, pressing buttons on and off, checking fuses etc with a torch only to find the muppet 2 boats along had uncoupled me to try his lead in mine, then continued to watch Corrie without any consideration.

He had positioned his lead in such a way that it ran in a groove where mine did, so when I looked out to the bollard it looked like all was well with my connection, trips up as usual !!!!

Needless to say when I questioned him he was quite unaware that my lead was actually doing anything or connected to anything so saw no harm in disconnecting it. When I asked him for a couple of quid to pay for the electric he had used off my card he told me to go away and stop being silly I nearly threw him in !

Chatting to the marina manager the following day, the chap wasn't even supposed to be there. He had literally come in off the cut thinking he could just moor up in someones spot and hook up free of charge...................

Hi everyone,

Have been reading the various comments with interest, having been a "Boy Sparky" for 45 years!
One thing it may be useful to clarify is the difference between the two possible means of protection involved in Electric Hook-ups and Motor home mains electrics.

Minature Circuit Breakers (MCB's) are designed to trip at a pre-determined current (load), ie 10amps, so if you exceed the limit, even by a small amount, out it goes, and has to be reset.

Residual Current Devices (RCD's) are designed to trip at a very low and pre-determined trickle of current away to earth, ie 30mA. You can overload the circuit all you like and they will sit there quite happily, as long as the leakage current is not exceeded.

MCB's protect the circuit, and will quite happily allow you to be electricuted. RCD's don't care about the circuit, they are there to protect people from being electricuted!

So, under the circumstances mentioned, if there is an earth fault on the wiring to a socket or device, even if the device is not switched on, an RCD, if fitted, will trip. So it may be a good idea to be clear what's protecting the EHU, from the pillar through and into the van wiring, and maybe that will offer a pointer.

Hope this helps

Jeff

Thats brilliant Jeff, thanks for that, I've just learnt something, very clearly put as well