Habitation electric cutout - WHY?

Apr 30, 2013
31
14
Newark
Funster No
25,773
MH
Van conversion
Exp
30 years
having had a number of continental vans in the past, where the 12 volt systems remained on when the engine was started, it has become more than an irritation that my Autotrail Vline (and others) cuts all 12 volt systems when the engine is started.
I came across this paragraph whilst trying to research this:
"CAMPERVAN CIRCUIT ISOLATION
There is a potential risk that appliances being used when the camper is being driven may divert power away from the vital systems of a vehicle: braking and engine management etc.
An isolation relay automatically cuts off the power to the living area when the vehicle is started. The fridge and the charge to the leisure battery can bypass this relay for obvious reasons."

If this is the case, how is it that there is no such risk in ALL continental vans - including all sold here in UK - and who do I approach to get a definitive answer? It has been suggested that it is a regulation from the NCC - if so again why??
Anyone help here??
 

pappajohn

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Aug 26, 2007
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It's complete rubbish.
It's part of the national caravan councils recommendations which UK motorhome converters mostly adhere to because they think it matters.... It has no legal standing
If it was the case there would be foreign vans broken down all over Europe.
If you could find the relay it can easily be bypassed allowing the hab electrics to remain live with the engine running.
 
Aug 6, 2013
7,609
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Kendal, Cumbria
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since 1999
It's to do with EMC regulations. Everything electrical that's installed in a vehicle must be EMC approved or have a certificate of exemption. To gain approval all electrical bits'n'pieces would need to go through a no doubt expensive process. So the industry doesn't do it. There are many links to EMC information. This is the first one I found:


It has to be said that there are few active (in terms of EMI) components used in a motorhome so bypassing the device that turns off habitation electrics when the vehicle is in use poses no danger. As evidenced by all the Continental motorhomes that don't bother.
 

DBK

Jan 9, 2013
13,486
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Plympton, Devon
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2013
Our British built Murvi doesn't turn the 12 volt system off when the engine is started. We regularly charge tablets and phones while driving and it would be a bind of we couldn't do that. So much so the relay and I would be having words. :)
 
Oct 20, 2018
427
361
Teesside
Funster No
56,835
MH
C Class
Exp
Since 1990
It may be NCC approved but Adria is Slovakian, not British.
Our Benimar is NCC approved for what little it is worth (ie, nothing), and Benimar, Autotrail and Adria are owned by the Trigano Group. The Autotrail Vline is made in Grimsby.
 
Last edited:

hilldweller

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Dec 5, 2008
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If you could find the relay it can easily be bypassed allowing the hab electrics to remain live with the engine running.
Maybe not so easy when Mr Sargent is involved. The engine running feed also retracts the step and sets of a hooked up warning so I suspect the "relay" is embedded in their control system and can not be simply bypassed.
 
OP
P
Apr 30, 2013
31
14
Newark
Funster No
25,773
MH
Van conversion
Exp
30 years
Thanks to Tonyidle on the link to the 'EMC standards'. Further research provided this -:

UNECE Regulation 10.

"Certain types of equipment are exempt from certain tests. Equipment for caravans and motor homes that operate when the vehicle is in use are included, but those that only operate when the vehicle is parked or are powered independently are excluded.

The Regulation is enforced by a different body in each member state. In the UK, the responsible body is the Vehicle Certification Agency (VCA), which is an agency of the Department for Transport. "
So it would seem that it is the VCA/DOT that state we must cut all supply when starting the engine because
" Products without direct control (of the vehicle) only have to meet the emission requirements."

All electrical items that meet these standards are CE marked - so it still raises the question as to why UK built vans - which have CE marked electrical fittings have to do this? Or are we (UK) fitting Chinese non CE marked electrical items??
Will be questioning VCA about this, and look forward to their answer.
Have approached Sargent re: disabling the cutout and received short shrift!
 
OP
P
Apr 30, 2013
31
14
Newark
Funster No
25,773
MH
Van conversion
Exp
30 years
To DBK, I would be most grateful if you could let me know the age of your Murvi - as I would like to contact Murvi to ask how they manage to NOT cut the habitation electrics?
Thanks.
 
Jun 30, 2013
4,716
6,862
Cotes d'armor, France
Funster No
26,730
MH
Burstner Harmony TI 736 G
Exp
Since 1987
We suffered the 12v cutouts in both our Swift and Autosleeper. A total pain.
We can use everything in our Burstner, including the heating and hot water, while we are travelling.
No more sitting freezing in the winter because the cab heating can’t keep up and rear passengers are also warm and can use any of the numerous spotlights to look at whatever they want to look at while travelling.
 

JeanLuc

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Nov 17, 2008
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No help for current owners but a simple solution for all future purchasers - don’t buy British!
 
OP
P
Apr 30, 2013
31
14
Newark
Funster No
25,773
MH
Van conversion
Exp
30 years
I shall be questioning most if not all British manufacturers as to their reasoning for this anomaly,
and reproduce their replies here. Perhaps with sufficient support - including as JeanLuc suggests the buying public's reluctance to purchase British, we can get this changed.
 
Oct 2, 2018
89
69
leicestershire
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56,515
MH
swift suntor 630G
Exp
since 1994
the light above the rear seatbelted seats and 12v/usb socket(if fitted) next to it usually work with engine running
well it does on my 2003 swift and on everyone i looked at when shopping for it

i have read about the one wire that needs to removed from the relay to enable full 12v use when engine running but depending on your wiring the removal of that wire could also affect your leisure battery charging, fridge, step, etc
 

funflair

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Dec 11, 2013
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Our British built Murvi doesn't turn the 12 volt system off when the engine is started. We regularly charge tablets and phones while driving and it would be a bind of we couldn't do that. So much so the relay and I would be having words. :)
Interestingly Murvi don't appear on the NCC list of approved leisure vehicle models. Does it have an NCC sticker?

Martin
 
Mar 11, 2016
4,563
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Bristol
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41,967
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Fiat Ducato PVC
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12
Our IH has live sockets in the habitation when running. As DBK Says, it would be a pain not to be able to charge things. I have not tried using the TV or toilet flush whist on the move so cannot vouch for those :rolleyes:
 
Apr 27, 2008
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Murvi are considered rather good so not being NCC approved is probably a good thing. I'm sure NCC would approve any old rubbish as long as the fee was paid.
 
Aug 6, 2013
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If I've found the correct Sargent drawing removing the link between terminals 9 and 10 on the Sargent unit should disable the 12v cut-off. Terminal 9 is labelled 'EMC' and terminal 10 is labelled 'Split Charge'. So the habitation battery charging and fridge operation is initiated by a signal from the engine running on terminal 10. The same signal is connected to terminal 9 to turn off hab electrics. Could anyone with a Sargent system confirm that 9/10 are linked?

This is the drawing I found:

sargent-ec160-wiring-diagram_orig.jpg
 

funflair

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Haven't found one yet. But as NCC standards seem a bit archaic that may be not be a bad thing. :)
I wasn't trying to suggest it was a problem, but it might explain it working right :LOL: (y)

Martin
 
Reactions: DBK
Feb 26, 2019
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N00B !
A CE marking will simply mean that it is tested and certified for standards in specified conditions. So something that is CE'd for static use, won't be CE'd for mobile conditions, hence needs to be isolated in UK vehicle regs when "under way".

I dunno but I suspect the regs were implemented only a few years ago. A couple of posters suggest their MHs are 2010 or older and perhaps the regs didn't exist then?
 
Nov 22, 2007
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East Yorkshire
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900
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Rapido "A" Class, Mecedes
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18+yrs plus 25+Towing
The most annoying thing about my Rapido/Merc. is the fact that the hab door "autolocks" after 15 seconds.!. Anyone know how to bypass that?
 
Nov 30, 2017
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Cornwall
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A CE marking will simply mean that it is tested and certified for standards in specified conditions. So something that is CE'd for static use, won't be CE'd for mobile conditions, hence needs to be isolated in UK vehicle regs when "under way".
That's the nub of the problem. To fully test CE for all the appliances fitted to a MH, including the wiring to all of them, would mean testing all of them in their final assembly (i.e. a finished motorhome) - this would be an extremly expensive operation because it would need a very large test chamber and a huge amount of time (because there are so many potential things to test). OK if you're selling hundreds of thousands of (say) fridges but not if you're only selling a hundred motorhomes a year. I write with some experience as I have designed electronic products and got them through EMC - but it took a long time and these products were only very small and worked off batteries.
What I don't really get, though, is how other countries have avoided this requirement - is it that the UK authorities (NCC?) are applying the rules differently, or that UK manufacturers are too afraid to look into it properly and it's easier to avoid the whole issue by simply turning thisngs off?
 

hilldweller

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Dec 5, 2008
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Could anyone with a Sargent system confirm that 9/10 are linked?
Now there is a challenge. I've to attempt to ease out our Sargent unit that is jammed into an overhead locker. Experience says that with the shedload of wires connected one will break.

After living with it for a year and having wired on some 12V sockets it's not a real problem, until we stop for a pee and the cry goes out "can you turn the water on".
 
Oct 8, 2014
368
331
Wiltshire
Funster No
33,737
MH
Autotrail Excel 600B
Exp
Previous VW Camper + Caravan
There is one advantage to the power going off ... if you stop driving at night for a bit, you can leave the Hab lights on while you get back into the driving seat, and they will switch off once the engine is started. I have wired in a couple of fused USB sockets directly to the Leisure Batteries for chargers etc.
 
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