Electrical Help on 2002 Talisman

Hi Everyone (Happy New Year)

Back in October we were staying on a site and my wife flicked on the heater switch in the wardrobe and there was a loud bang from under the seat housing the water heater and smoke poured out for around 20 seconds or so. I was folding up the bed back into a seat at the time so got a bit of a surprise but the smoke stopped so I didn't have to use the extinguisher. My best guess was that the water element has blown (hot water was on) and I have finally got around to removing it and it looks fairly worn out but then it's probably 18 years old (see below). I have ordered a replacement but am concerned that the Plug in Systems Consumer Unit in the wardrobe didn't trip at all and wonder whether anyone can recommend the best approach to ensuring the new element doesn't go the same way as the last as soon as it's fitted? I am trying to find a reputable auto electrician in South Gloucestershire to check over all of the electrics anyhow (any recommendations?) but any advice around this would be appreciated. I have read lots of examples of electrics tripping when you don't expect but not the opposite!

Thanks
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Colin Ponder

Thanks Peter, i'll get outside and have a look in the morning...

Maybe  not the same but the heater stoped working on our Rienza. The switch with the red led on the control panel wasn’t lit when on hookup.
As a matter of basic checks I found the switch had a fuse holder built in it and this had melted. A replacement switch didn’t help blowing the supplied fuse as soon as the heater was turned on.
After a bit of a think and advise from an electrician I tried a slow blow fuse. This cured the problem and has worked fine for quite a while now. 
Being old school motor trade fuses are fuses. Vehicles of my time had fuses, some older cars didn’t have any fuses. Slow blow fuses are from the electronics age or domestic electrics in motorhomes.
If all fails you should have gas for hot water saving agro from domestic management. No water halfway through a shower cased some grief last trip.

Thanks Dave, interesting. I have been thinking about the circuit breakers in the Consumer Unit rather than fuses which, as you say, is more like we had in 1960s/70s cars. I'll dig out the circuit diagram and see what it should be like (in theory) and go from there.

Really don't like having to make that wet dash in a towel (hopefully) from the van to the shower block either!!

I have just had a thought having re-read you’re original post. If the water heater switch is in the cupboard it is the older system. Sorry to miss lead you. I can’t remember were the fuses were in our Duetto.
The damp dash to the toilets is not for us now. We did that for long enough with the kids tenting. Our daughter threw managements clothes in the shower on one occasion. Night time visits to the toilets are now age related and I am not wobbling to the toilets after dark any more. That’s why we have a fully fitted motorhome.

 Happy Days!

The most common failure mode of an immersion heating element is that the outer casing breaks down due to limescale buildup and water will soak into the insulation material inside the element.  Not long after that the bare heating wire at the centre of the element will short circuit to earth potential.  This is precisely the fault condition for which a residual current device (RCD) is designed to provide protection.  It operates within milliseconds of this type of fault occurring.

Many domestic electrical installations do not have RCDs so the same will be true of older vans.  It wasn’t until 2015 that the IEE Wiring Regs made them mandatory for virtually every installation.  In the case of caravans and motorhomes the risk is deemed to be greater and an RCD is required for the whole 230V system.  If your van doesn’t have one then I would recommend you have one fitted.  Campsite bollards are required to incorporate them but you can’t rely on that being the case or that it will operate correctly even if present.

The fuses and circuit breakers are designed to protect the electrical system from over-current damage, but sometimes may not operate  be fast enough to prevent smoke and heat effects mentioned in your post and others.  By contrast the fast-acting RCD is designed to protect lives.

Tim

Thanks for your advice Tim. I'm about to go out to have another look at it. I'm learning a huge amount about how my van works (realise I didn't really understand how any of this hung together) so, whatever the outcome, I feel much better equipped to use the van safely in future

Tim is quite right about the benefits of having an RCD, but I'm reasonably sure that by 2002, A/S would have been fitting them to all their conversions. Certainly my Flair (built 1999) had one installed.

If you're uncertain, it may be worth taking a photo of the fuse panel on your phone and posting it up here, as someone here will almost certainly know.

The one distinctive thing about an RCD in that situation is that it will have a "Test" button next to the main incoming circuit breaker, and if you press it (with EHU connected and the main circuit breaker on) it should trip the circuit breaker and cut off all internal mains power.

Hi Roopert, yes, it has the 'Plug-In Systems' brand Consumer Unit with two 10A and one 6A MCBs. I have tested it as you described and it works fine. I have also checked various fuses on the control unit and under the driver's seat although think most of these are to do with 12V circuit. I'm losing the light now but reckon i'll fit the new element in the morning, put some water through it and switch on......watch this space!

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I bought a replacement reconditioned 12v transformer which worked fine. Seems a decent guy happy to give advice.

Hope this helps