Dandy Wiring

I mentioned in a previous thread the need to find the end of the grey 12S cable in my Dandy Destiny before completing the conversion to the 13pin towing socket standard, as the previous owner had warned me that it was not wired correctly.

I found it quicker than expected at the weekend when trying to fit a packing crate into the under-sink cupboard. It wouldn't fit due to a false back in the cupboard that took around 6" off the depth. I quickly removed the panel at the back and found this -

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Not a pretty sight With the very poor termination and lack of any strain relief on the cables it's surprising they've lasted this long without problems.

The green and white cores have been used (pins 4 & 3) have been used for battery charging / 12 volt supply from towcar, which is fairly standard for the year of manufacture, however the fridge is wired to brown and black (pins 5 & 7). Pin 5 is not used in the 12S connector and the supply to the fridge should be on the red wire (pin 6). Oddly, the red wire is terminated (sort of) in the connector block, but not used for anything.

As I was re-wiring everything, I removed the fridge to check what was behind there. The connections to the water pump were also very poorly terminated and had clearly been crimped with a sidecutters or pliars.

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Needless to say there's not a fuse in sight

I rewired what I could although I later found that the supply to the light in the toilet compartment and the one beside the door has been taken by splicing into the grey 12S cable somewhere along it's length between the hitch and the under-sink cupboard. That's buried in the wall somewhere so I didn't investigate further at this stage.

Next step is to make up a control / fuse panel to properly terminate and protect the supplies to the various equipment and then I can complete the wiring to the 13-pin plug. I also plan to fit a car radio head unit and some 12 volt sockets.

I'll update the thread with any more 'interesting' discoveries I make.

12 volt electrics does not appear to have been one of Dandy / Riva's strong points so it's well worth checking out the wiring on any Dandy for loose / exposed terminations. It's also very worthwhile to fit at least one fuse in the supply from a leisure battery. If there's a short circuit and no fuse protection, the wiring will act as a fuse and melt - most likely setting fire to the camper in the process.

Wow!!

The frightening thing is that this is probably Riva's wiring when the unit was originally manufactured in 2007. Standards should have been good by then. Obviously their electrician had a day off or hadn't been paid, so someone else did it. Dare I ask whether there is a NICEIC certificate for it. I do have one with my new Bailey caravan.

People just do not realise that 12volt electrics from a car or leisure battery are more dangerous, from a fire point of view, than 240volt household electrics as therre is more current (Amps). At least in a house there is a fuse in the electricity board cut out.

As far as I can see, all the wiring is stranded conductors which is correct. Household wiring with solid conductors must not be used in Dandys as they are subjected to vibration whilst towing.

Just my way but i wouldn't run gas pipe like that over heat the electric and what do you get

Similar looking connection block in the same place on our 2006 Dimension. It was wired differently again! - Lights, pump and fridge all wired to the green/white of the 12S wiring. The red/black for the fridge were unused.

I'm planning to fix things.

Steve

navver wrote:The frightening thing is that this is probably Riva's wiring when the unit was originally manufactured in 2007. Standards should have been good by then. Obviously their electrician had a day off or hadn't been paid, so someone else did it. Dare I ask whether there is a NICEIC certificate for it. I do have one with my new Bailey caravan.

Yes, I'm fairly certain that it hasn't been touched since build as the previous owner had rewired the 12S cable at the hitch end rather than look for the termination in the camper as he thought it was probably behind the fridge and didn't want to remove it. I don't know if it was cost-cutting in the dying days of Riva but I doubt that any qualified sparky has been near the wiring. There are certainly no certificates in the comprehensive documentation pack that came with the camper although, while I haven't investigated the mains installation fully, it does appear to be to a much higher standard.

People just do not realise that 12volt electrics from a car or leisure battery are more dangerous, from a fire point of view, than 240volt household electrics as therre is more current (Amps). At least in a house there is a fuse in the electricity board cut out.

Absolutely. I'm not sure what the point of the exercise in this video is but it gives an idea of the effect of a short circuit on a battery. A typical leisure battery will have a capacity at least five times greater than this one.

mike wrote:Just my way but i wouldn't run gas pipe like that over heat the electric and what do you get

Yes, I though the routing of the gas pipe was a particularly nice touch

Sounds like there may be a problem with wiring in the later Destiny's ..... that's a worry, perhaps people who have one should check just to be on the safe side.

I largely completed the battery / fuse box / motor mover controller installation at the weekend. A bit of a squeeze in the bottom of the undersink cupboard but storage space is precious and this is all I was allowed. Some nonsense about having to also store pots and plates and food and curtains and other such fripperies

The grey box houses the control relay/contactor to switch power to the motor mover in place of an isolation switch, a main switch and individual fuses for the other 12v circuits and a neat digital voltmeter that cost the princely sum of £1.56 on ebay (including postage from Hong Kong!)

I just need to extend the top shelf out, add a direct vent tube to the battery and probably improve the general ventilation of the area, although the "never mix gas and electricity" folk will have fits of apoplexy whatever I do


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Is that nut or wing nut on top of the battery part of the battery terminal. If so you may want to shroud it in case she drops a saucepan lid between it and the gas pipe.

I love the contactor enclosure and volt meter. That will be really useful to check on the charge level.

navver wrote:Is that nut or wing nut on top of the battery part of the battery terminal. If so you may want to shroud it in case she drops a saucepan lid between it and the gas pipe.

I love the contactor enclosure and volt meter. That will be really useful to check on the charge level.

I was going to point something out but now can't find what I wanted to illustrate.

Is that nut or wing nut on top of the battery part of the battery terminal. If so you may want to shroud it in case she drops a saucepan lid between it and the gas pipe.

I was going to say that as previously discussed the 240V supply was earthed but that that any ELV (12V) circuit must be isolated from the caravan (Dandy) body.

Being no electrician and not being able to knowledgeably read the nature of 17th edition instructions I've gone for the more prescriptive [You must be registered and logged in to see this link.] However reading this I can't find the mention of isolating the -ve side of the 12V supply.

My original point was that I think we had questioned whether most battery chargers are isolating transformers. Here I think I've found the guide that the transformer must be isolating. (and I suppose ergo that the -ve of the 12v supply must be isolated. I'm just wondering where we picked it up initially?) [You must be registered and logged in to see this link.]
Can't quote from this look at the piece above 608-08-09.
Come on gentlemen this is where I need the help of sparkys who know what they are talking about.

Battery covers always seem good to me. How close did you get to the battery for fuses? Did you fuse supply and return on the battery?

I will extend the shelf out to cover the battery terminal (probably by fitting a hinged section to allow for future access) This will prevent the terminal being knocked when items are pulled in and out.

The 12V system is isolated from chassis 'earth' as required by regulations. I think the relevant section of the 17th Edition is A721.515.2 - The [12V] installation should be so installed that the protective measures of the [mains] installation for basic protection or for fault protection are not impaired. It should be ensured that the protective conductors of the [mains] installation are not loaded by the operating currents of the [12V] installation. (I've substituted '12V' and 'mains' for the correct ELV and LV terms used in the regs to make it easier to read)

If both systems were connected to the chassis, 12V operating and fault currents would flow in the parallel earth wires of the mains installation, potentially overloading them. Similarly, in the event of a fault, mains fault currents could flow in the 12V wiring.

I've taken a 6mm sq. wire from the 'battery +' and 'battery -' terminals to the first two fuses in the holder, so it's a short run (~70cm) of unprotected wiring. It should really be double sleeved but as there is nothing for it to chafe on, I've left it as is. The third fuse is the battery charging input from the towing vehicle and the remaining 5 fuses are individual 12V circuits within the camper. I need to make up a label as it won't be long before I've forgotten this

That book is out of date. Section 6 is now Inspection & Testing. Electrical Installatons in caravans & Motor Caravans are now section 721.

If the 12v is earthed it is a PELV system (Protective Extra Low Voltage)you rely on the 240v systems protection to protect you if there is a fault. Basically the earthed metal (chassis etc) is common between 240v & 12v systems so a fault in the 240v would put 240v on the 12v system via the earth.

If it is a SELV system( Separated Extra Low Voltage) you are isolated and insulated from earth.

Reg 414.3 says sources for SELV & PELV must be a safety isolating transformer to BS EN 61558-2-6
or several other sources they quote such as battery, generator, electronic equipment with conditions ensuring no contact with higher voltages.

the remaining 5 fuses are individual 12V circuits within the camper.

Can't remember what you have said but imagine you are looking at non EHU useage. I might push myself to wiring up the radio separately then maybe due to a (misplaced?) sense of convention from house use splitting the sockets and the light fittings but two other circuits as well. I'm impressed but what are all the 5 fuses for?




Thanks gentlemen for the tech input. I'm just left wondering where I gained the knowledge that the low voltage sytem must be isolated originally?

So the question still stands are most battery chargers isolating transformers? Should I be expecting to see BS EN 61558-2-6 on the back of a charger? As the British Standards no is an EN one that is a European standard? What would I expect to see on a European produced product? (just noticed an European sounds wrong)

As I doubt either of you gentlemen are quoting this from heart are you using that old fashioned media of books or is there a better or newer caravan wiring guide on line?
As an aside what happens on motorhomes where on vehicles you have the convention of the body being used as part of the wiring.

I'm using BS7671:2008 Incorporating Amendment No 1:2011 Requirements for Electrical Installations IET Wiring Regulations Seventeenth Edition.

This is the current wiring regs available only from the IET formerly IEE for a considerable sum. Luckily I have a copy for work.

Not sure what most battery chargers would be, but a caravan/dandy charger is usually a power supply as well as a charger. Mine is the standard Riva fitment and works with or without a battery supplying up to 16A at 13.8V DC.

I don't know if mine is isolated, can have a look next time she is open.

[quote="Tow Itch"]

but what are all the 5 fuses for?

Have you looked at your car fuse box and seen all the fuses they have? With 12V DC the currents are so high (20 times higher than 240V), each circuit can only serve one or two items before the current becomes excessive. The cable is sized on the fuse rating as a minimum.

Tow Itch wrote:
Can't remember what you have said but imagine you are looking at non EHU useage. I might push myself to wiring up the radio separately then maybe due to a (misplaced?) sense of convention from house use splitting the sockets and the light fittings but two other circuits as well. I'm impressed but what are all the 5 fuses for?

I could have used fewer but it was as easy put an 8-way holder in as a smaller one, and it's easier to terminate the wiring with a single cable to each fuse way. There's also a spare way for some extra 12V sockets that I want to add.

Thanks gentlemen for the tech input. I'm just left wondering where I gained the knowledge that the low voltage sytem must be isolated originally? So the question still stands are most battery chargers isolating transformers? Should I be expecting to see BS EN 61558-2-6 on the back of a charger? As the British Standards no is an EN one that is a European standard? What would I expect to see on a European produced product? (just noticed an European sounds wrong)

I can't see any reason why a battery charger wouldn't have an isolated output so I imagine they all are whether required by standards or not.

I expect the marking to be found chargers will be the 'CE' mark. This marking is not particularly helpful as you need to know which European Directives apply to the product carrying it, and which standards are ultimately mandated under each Directive - not necessarily an easy task to determine.

I think the 'BS EN' identifies a European standard that has been adopted as a national standard confirming the withdrawal of older, and potentially conflicting, national standards.

As I doubt either of you gentlemen are quoting this from heart are you using that old fashioned media of books or is there a better or newer caravan wiring guide on line?
As an aside what happens on motorhomes where on vehicles you have the convention of the body being used as part of the wiring.

I was using the printed regs too. Interesting question regarding motorhomes - I have no idea what the answer is.

On motorhomes I suspect the vehicle 12V runs from the vehicle battery and the habitation equipment runs from a leisure battery. They will be separate systems like the 12S & 12N plugs. Vehicle systems can be connected to the body, habitation systems not connected. Also there will be a habitation relay which will isolate all the habitation systems when the engine is running.

The transformer must be isolating whether or not the 12v connects to the body. PELV or SELV.

Also motorhomes may come under vehicle regs rather than regs for buildings. Will check tomorrow.

Re visiting this and wondering did you ever find out the answer about the motorhomes navver? Also do standard transformers/ battery chargers tend to be isolating?

Just looked online at the instructions for the cahrger I have fro charging car batery etc. On the last page are some EN numbers and BS EN 61558-2-6 is not among them. But it is a batttery charger not a caravan LV circuits supply unit.

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