Motorhome Electric Tripped again!! Any ideas

[Jabstatt]

Just a thought…..

I had a Bessacarr caravan and replaced breakers almost weekly for months.

Problem turned out, my diagnosis, was that the ambient temperature in the compartment which contained the breakers was getting over forty so reducing the trip level!

Easy solution once diagnosed.

Just a thought.

Tony

 

[autorouter]

I think the reason a 13A RCBO is chosen (rather than a 16A) is because it is supplying the UK sockets. The plugs will have 13A fuses in them. A fuse is obviously a single-pole protection device, so to pre-empt the fuse, a 13A breaker is used. That's because it will probably trip before the 13A fuse blows, and give proper 2-pole disconnection.

It's a good idea - except that some plugs have 5A or 3A fuses if they are supplying low-power things like chargers. There's no other reason. A standard UK domestic ring main with 3-pin 13A sockets usually has a 32A breaker on it. So using a 16A RCBO instead is perfectly safe as far as overcurrent protection is concerned.

 

[AdrianChen]

Carthago don't appear to have a set standard, mine had a 16 amp RCBO on the input with the output feeding the heater and the 13 amp MCB which feeds everthing else.

They knew you would rip it all out anyway!

That is how ours were arranged, but these two were the originals, both RCBO Suppose as you say it depends what's in the parts bin....

 

[RustyRuss]

Hi Glyn

Pretty much everything Lenny said plus I’d add a few comments.

The yellow breaker is a 13A RCBO curve type B.
It can handle 13A*240v=3,120w (or if your system is 230v then 13A*230v=2,990w), so capable of roughly 3kw before the “overload” drops it. From what you’ve said it’s unlikely that you’re exceeding the load limit.
The breaker also drops when there is a difference between positive and neutral exceeding 0.03A (30 milliamp), and this is likely what’s causing the drop…. if the RCBO is not faulty.

We’ve had to replace the odd faulty RCBO, MCB and RCD. Not common but it does happen. To avoid chasing your tail and before doing the tests Lenny has suggested I’d advise you to change the RCBO just in case. It’s the easiest starting point.

Screwfix have a few 16A to choose from, here is a search link:

https://www.screwfix.com/c/electrical-lighting/rcbos/cat7230024?curvetype=b_curve&ratedoperationalcurrentin=16_a

They are not the exact same form factor as your existing RCBO and higher load but they should do the job. You could also go to your closest B&Q or Toolstation. You’ll find very few options for 13A but if it was me, assuming the wires can carry 16A I’d be happy with that in my own van. Your 240v wires are almost certainly 2.5mm which is fine for 16A. You may need to get a small blanking plate as the Screwfix ones are narrower than yours.

I think RS-Online may have one very close to yours:

https://uk.rs-online.com/web/p/rcbos/1833539

You will need to get an RCBO SPECIFICALLY for a motorhome, I suggest a Moho dealer with a spares department. However I doubt very strongly that the problem is the RCBO, they trip because they have detected a fault, not because they are faulty. They are supposed to trip if they detect a fault. The fault is likely to be with something that has water involved, so perhaps your water heater. Specialist diagnosis is the best way forward in my opinion.

 

[AdrianChen]

I think the reason a 13A RCBO is chosen (rather than a 16A) is because it is supplying the UK sockets. The plugs will have 13A fuses in them. A fuse is obviously a single-pole protection device, so to pre-empt the fuse, a 13A breaker is used. That's because it will probably trip before the 13A fuse blows, and give proper 2-pole disconnection.

It's a good idea - except that some plugs have 5A or 3A fuses if they are supplying low-power things like chargers. There's no other reason. A standard UK domestic ring main with 3-pin 13A sockets usually has a 32A breaker on it. So using a 16A RCBO instead is perfectly safe as far as overcurrent protection is concerned.

Being rubbish on 230v AC, I wondered why the sparky that did mine used a 16amp RCBO on the feed to the 32amp Multiplus which was in turn feeding the 16 and 13amp RCBO's, I guess it was cable sizes and plug/sockets, and the potential for someone to use a 1.5mm² EHU?

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[autorouter]

The switch that keeps tripping is the yellow one in the picture below. I had the heating only on 2kw, so nowhere near overloading, any idea please, I presume the yellow switch is faulty and needs replacing??

That switch, as others have said, is an RCBO. That has two functions. It trips if the current (amps) exceeds its limit, which is 13A. It also trips if the leakage current to earth exceeds 30mA. The problem with RCBOs is you can't tell which of the two problems is actually happening.

Leakage currents occur where the insulation between the live or neutral conductors and the earth starts to fail. This can have many causes. Favourites are water getting into plugs and sockets, or heater elements failing and leaking current to the earthed sheath surrounding it. Other possibilities like a squashed cable under a sofa leg are less likely in a motorhome.

There's no easy way to check, without specialist instruments like an earth leakage meter. You could try disconnecting each circuit it turn, and waiting to see if it stops the tripping. If the original tripping is intermittent that could be a long frustrating job.

It's also possible you are simply exceeding the current (amps) rating of the RCBO. For example the heater rating of 3000W at 230v would be 13A, but the same element at 240V would take 13.6A, which might be enough to cause the occasional nuisance tripping you are seeing. The heater is rated at 3000W, but the actual rating might be slightly higher or lower due to manufacturing tolerances. If it was 10% higher then it would be taking 14A at 230V, and a bit more at 240V.

Might be worth taking up Nigel's offer of looking at it in their workshop.

 

[nigelivy]

Might be worth taking up Nigel's offer of looking at it in their workshop.

After talking to Glyn, I suspect that it is exceeding the RCBO’s current limit rather than an earth leakage in the system. We’ve got a plan to get Glyn into the workshop so we can take a look and get it sorted.

 

[Gromett]

You will need to get an RCBO SPECIFICALLY for a motorhome

I am sorry but there is no such thing. RCBOs are specified by trip current, current carrying capacity and number of poles (just to cover the basics).
There is no such thing as one specifically for a motorhome or caravan.

For Motorhomes and Caravans you want a dual pole so that both the live and the neutral are disconnected. This is to prevent issues where if the live is swapped in the EHU cable, the hookup point or back at the building.
If a trip happens in these circumstances and you have a single pole disconnect on the live. Then the live will still be connected to the neutral in the van and you stand a risk of still getting a full voltage electric shock.

As an example to clarify. If the Hookup cable is wired accidentally with live and neutral reversed everything will work normally. But if your van develops a neutral earth fault. In a single pole RCBO the trip will disconnect the live. This will leave the live connected (on the neutral connector) and potentially to earth meaning that if you step out of the van and touch the chassis there will be a direct route from live down to the ground and that wouldn't be pleasant for anyone. You would hope the posts RCD would then trip, but would you bet your life on it?

 

[xsparks]

It could just be low input voltage. Worth checking if you can.

 

[autorouter]

There is no such thing as one specifically for a motorhome or caravan.

In the UK, most RCBOs fitted into domestic and industrial consumer units are single pole switching. All the ones you can buy from DIY stores like Screwfix and B&Q are single-pole types. From an average electrician's point of view a double pole RCBO is special, for 'special situations' as it says in the regs. So I can see why an electrician would consider these double pole RCBOs to be just for motorhomes, caravans and campsites.

Outside the UK it's different, all the RCBOs, RCDs and MCBs are double pole. You can find them in any DIY store.

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[G1969]

From memory (highly fallible) we removed one of the two CBE chargers that was OE fitted. This left a spare white socket/plug that would be on the 13amp breaker - wonder if that is the cause if it’s found a way of touching something it shouldn't.....

That’s interesting as yes, both mine are left in situ- but disconnected (I think) see pic . I will leave it to the professionals ( Roger & Nigel) to sort/correct

for me.

 

[WESTY66]

That’s interesting as yes, both mine are left in situ- but disconnected (I think) see pic . I will leave it to the professionals ( Roger & Nigel) to sort/correct View attachment 1002159View attachment 1002160for me.

I think you need more blue in there

 

[Gromett]

In the UK, most RCBOs fitted into domestic and industrial consumer units are single pole switching. All the ones you can buy from DIY stores like Screwfix and B&Q are single-pole types. From an average electrician's point of view a double pole RCBO is special, for 'special situations' as it says in the regs. So I can see why an electrician would consider these double pole RCBOs to be just for motorhomes, caravans and campsites.

But if you go into an electrical wholesaler and ask for a motorhome RCBO they will have no idea what you are on about and probably suggest you go to a caravan dealership.
If you ask for a double pole RCBO they will know exactly what your are on about

 

[Raul]

Just caught up with this tread, pretty sure this is a overload, no earth leakage. An RCD of 30mA will not trip until exceeds its 1/2 Ind rating of current leakage. Thats 15mA of current and very unlikely, unless the water heating element is considerably shorting to earth.
The multiplus will easily overload the 13A rcbo, to test you can limit the multiplus at 12A or even11A from EHU, to allow for low incoming voltage as well. I bet it will never trip for months.
If it was a leakage, would trip as soon as you put load on it, in about 40-300 miliseconds.
Change the RCBO to a 16A. It is perfectly fine to feed a 2.5mm2 radial circuit in the van. We don't have ring mains in the vans, not allowed.

 

[Raul]

This is a good example of what you need.

https://www.cef.co.uk/catalogue/products/4946301-16a-double-pole-2-module-b-curve-10ka-30ma-type-a-mini-rcbo

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[autorouter]

I wondered why the sparky that did mine used a 16amp RCBO on the feed to the 32amp Multiplus which was in turn feeding the 16 and 13amp RCBO's, I guess it was cable sizes and plug/sockets, and the potential for someone to use a 1.5mm² EHU?

You have a 32A Multiplus - is that a Multiplus-2 8000? I feel an attack of inverter envy coming on... I presume it is paired with 48V batteries. It would be limited to 16A in the same way that I sometimes set my Multiplus-2 3000 to 5A or 6A when on a site with low amps hookup. A standard motorhome inlet plug and socket is designed for 16A, so best not to exceed that.

You could fit a round blue 32A inlet, which looks very like a 16A but is slightly bigger. You could then plug it into a 32A supply if you can find one. Maybe one or two on a big marina site, or on a town centre aire that is used for markets and fairgrounds. But they are quite thin on the ground. You'd need an adaptor to plug into a standard 16A hookup. Or fit both a 16A and 32A inlet, with a transfer switch to select the one you want.

 

[Raul]

autorouter, the 32A is on all multiplus 3kva, the 2kva is 35A, the 5kva is 50A and from 8kva up, all are 100A.

 

[AdrianChen]

You have a 32A Multiplus - is that a Multiplus-2 8000? I feel an attack of inverter envy coming on... I presume it is paired with 48V batteries. It would be limited to 16A in the same way that I sometimes set my Multiplus-2 3000 to 5A or 6A when on a site with low amps hookup. A standard motorhome inlet plug and socket is designed for 16A, so best not to exceed that.

You could fit a round blue 32A inlet, which looks very like a 16A but is slightly bigger. You could then plug it into a 32A supply if you can find one. Maybe one or two on a big marina site, or on a town centre aire that is used for markets and fairgrounds. But they are quite thin on the ground. You'd need an adaptor to plug into a standard 16A hookup. Or fit both a 16A and 32A inlet, with a transfer switch to select the one you want.

No its just the common 3kva - but could be paralleled with a second.....

Yes that was on my mind a 32amp cable for the odd occasion with marinas, but not sure it's worth the effort really. Even most marina berths are 16, we had a 32 purely by chance on the last mooring I had but it did make me think....

I would carry two leads with appropriate ends. I have all the hardware in my old boat and standby generator "box of bits", sitting next to my offcuts of wood that may come in handy....

Just thinking about what I would do if I put a serious amount of lithium on board....

 

[mikash]

No its just the common 3kva - but could be paralleled with a second.....

Yes that was on my mind a 32amp cable for the odd occasion with marinas, but not sure it's worth the effort really. Even most marina berths are 16, we had a 32 purely by chance on the last mooring I had but it did make me think....

I would carry two leads with appropriate ends. I have all the hardware in my old boat and standby generator "box of bits", sitting next to my offcuts of wood that may come in handy....

Just thinking about what I would do if I put a serious amount of lithium on board....

A while back I humoured myself for a bit by looking into what it'd take to build a "quick charge" kit for (ab)using type-2 EV chargers. You could get single phase 32A from those too with a cable with some smarts you can buy off amazon, but back then I couldn't figure out a cost effective setup for 500A+ worth of chargers. Obviously need big enough pack to handle the current too. Still, the thought of pushing 250Ah+ into your batteries during a 30min grocery run is kinda cool