# Fuses blowing in circuits to 12 v sockets- why ?



## Grizzly (May 9, 2005)

We have 3 x 12 v sockets in the hab area of our 2014 AS Broadway. They are protected by a 10 amp fuse. There is nothing other than the TV aerial amplifier on the same circuit. 

When plugging in any one of our 2 amp rated Kindle, phone or tablet chargers ( all of which are manufacturers supplied chargers, not cheap copies ) the 10 amp fuse often blows, often with a small spark as well at the socket. 

The only reason we can think of, given that there are several sockets and several chargers, is that there is a current surge on start. 

When the charger, and device being charged, is plugged in with the 12 v supply turned off and then the 12 v supply turned back on again all appears to be well and the fuse does not blow.

We did not have this problem with our old ( 2007 version) Bessacarr using the same charger units and devices.

Has anyone experienced the same problem ? Can anyone think of an alternative explanation and a solution ? 

G


----------



## prof20 (Jan 11, 2007)

I can't offer a solution, Grizzly, but why, with a 2014 van, haven't you gone back to the dealer with it?

Mess with it and invalidate your warranty perhaps.

Hope you get it sorted.

Roger


----------



## Techno100 (May 8, 2010)

Sounds like the socket is a poor connection but chargers have a start up current surge too. I'm surprised the fuse is a meagre 10 amps


----------



## cabby (May 14, 2005)

does this happen with using any of the three 12v sockets, or just the one. does it matter which charger you plug in to make this happen.
It sounds either a surge, which means a higher rated fuse, or a lose connection.
were these factory or dealer fitted.

cabby


----------



## Grizzly (May 9, 2005)

Thanks all, we're in France at the moment so can' t take it back to the dealers. All our UK trips, since we bought the van in Spring, have been with hook ups so we have not noticed this before. We are now on Aires and rapidly running through the stocks of French fuses.

The fuses blow whichever socket we use or whichever charger we use. The sockets are all original manufacturer( AS) fitted. 

We have a work around in that if we plug in the device when the 12 v supply is off then, switch it back on again, it does not blow. This is fine if we remember to charge things in daylight as, doing it after dark means we have to work without lights !

It could be that the fuse is not big enough but that presumably means that the wiring is also not up to the job.

Are there such things as slow- blow spade fuses ?

G


----------



## Techno100 (May 8, 2010)

Yes a 15 amp :lol: but seriously I can't imagine that they've used such small cable to warrant 10 amps.
Have you got any information with it to confirm that 10 is the correct size?


----------



## stevegos (Jun 23, 2013)

I would have thought that the 10a fuse will cover the 12v whether it is from the battery or when on hookup. It does on my motorhome.

I have seen before where the metal negative collar inside the 12v socket was loose and pushed back against the positive pin at the back when a plug was pushed in and causing a momentary short when pushed in. check it is all tight.

10a fuse does sound a bit low. I have 15a in mine, but if its meant to be 10a then better keep it that way.

Have you isolated the aerial amp? It may have a fault (but appear working) and the kindle/phone chargers may be taking the draw over the limit. Remove the aerial amp and see if it makes any difference.


----------



## cabby (May 14, 2005)

As a further check, with the 12v turned off, can you plug in all the chargers to the three sockets. then turn back on and in turn connect the apparatus to each charger, without disturbing the socket. As you say during the daylight hours would be best.  Are you sure that 10 amps is the correct size.

cabby


----------



## Techno100 (May 8, 2010)

I just checked mine and they are fused at 20 amps from my CBE panel


----------



## Bigusdickus (Nov 6, 2012)

Have you got the correct plug on the cable to fit the socket, sounds like a dead short to blow a fuse and the spark at the socket is a clue.
Bd..


----------



## Grizzly (May 9, 2005)

Yes, 10 amp is the size of the fuse according to the manual., The plugs on the chargers are all, as far as we know, correct for the sockets. It would be odd if AS put a unique type on that did not fit the standard 12 v charger bought with Kindles, phones and tablets. They all work in the 2 x12 v sockets on the cab dashboard as does the satnav charger. The TV 12 v power plug, which goes in the same sockets is fine and doesn' t cause any fusing. It looks exactly the same, externally anyway, as the others.

Yes, we can plug them in with 12 v off and they remain on when 12 v is turned back on again but it would be nice to know why we can, t use them as intended. 

A nice touch by the way...the Peugeot garage round the corner from the aire at Gravelines, would only allow my OH to buy one ( 22 cent ) fuse per visit ! We got a few dozen from Auchan next day however. 

G

Edit to add: the aerial amp is normally off anyway.


----------



## Penquin (Oct 15, 2007)

The thing that triggers my brain cell is that it happens AS YOU PLUG IT IN.....

this to me would suggest that the short is occurring at that point, and that point only.......

it cannot be a fault in the items plugged in since once in and then turned on the same short would still be present and would still blow the fuse....

BUT the fact that it happens with several sockets and several plugs tends to negate that line of thought.....

Each of the 12v items you are plugging in does have a separate plug doesn't it? You are not using a 12v splitter or anything similar?

The 10a fuse should be enough for a 2a appliance - and the 2a rating is the MAXIMUM it should ever take on start-up.......

I would check that the plugs are going in absolutely straight so that there is no way that they can bridge the short gap from the negative surround in the socket and the positive spring loaded plunger at the base...... that is the only other thing that comes to my mind at present, but I would be interested to hear what the problem is eventually diagnosed as....

Sorry not to be of more help.....

Dave


----------



## Grizzly (May 9, 2005)

Thanks Dave, No, no splitter being used. Latest theory chez nous is that it is that when making contact the plug is so " uncertain" that it is making several contacts in short order leading to several spikes and so causing a short.

We have never had problems with this make of socket before which makes it all the more puzzling.

Never mind, any excuse for another go at the garlic mushrooms in the Bell at Willersey...

G


----------



## cronkle (May 1, 2005)

Hi

Following other people's line of thought made me wonder if you plug a splitter in does this happen. If it does its tells you something (though I'm not sure what). If it doesn't affect the fuse try plugging something in and if the fuse pops then it's not the mechanical action of putting the plug in and some sort of power surge looks more likely. But then, what do I know


----------



## Grizzly (May 9, 2005)

cronkle said:


> Hi
> 
> Following other people's line of thought made me wonder if you plug a splitter in does this happen. If it does its tells you something (though I'm not sure what). If it doesn't affect the fuse try plugging something in and if the fuse pops then it's not the mechanical action of putting the plug in and some sort of power surge looks more likely. But then, what do I know


We're a bit leary about using any of the sockets at this stage for chargers as we don' t want anything else to be affected while we're in foreign parts. We want to watch a DVD tonight so will have to plug the TV into one of the offending sockets but that always works via the 12 v supply whether we are on hook up or not and has always worked fine.

Should anyone on the south coast hear a big bang and a lot of ***### type words then you' ll know that it hasn' t worked fine tonight.
G


----------



## cabby (May 14, 2005)

I am on the south coast, are you still in France then.
It would be an almighty bang if it does go. :lol: :lol: 

cabby


----------



## Grizzly (May 9, 2005)

cabby said:


> I am on the south coast, are you still in France then.
> It would be an almighty bang if it does go. :lol: :lol:
> 
> cabby


Yes, a_rather damp Montreuil sur Met, below the ramparts.


----------



## Glandwr (Jun 12, 2006)

A wild guess suggestion. Turn off the 12v switch put a piece of toilet/kitchen paper around your finger and give the inside of the plug(s) a good clean. There could be something that causes tracking across the surface as you plug in. 

Dick


----------



## listerdiesel (Aug 3, 2012)

If they work by turning off the 12V supply, plugging them in and then turning the supply on again, it cannot be start-up surge as that would happen when the 12V supply is restored.

Next is the source impedance (resistance) of the supply. If it is low, then the current flow into anything is going to be high as there is no resistance to reduce that current. If the source impedance is high(er) then there is a natural current limiting effect.

If the 12V feed is from a power supply or charger, they usually have soft-start circuits, so again the start-up current would be limited.

If there is an input capacitor in the devices you are plugging in, that will take an initial high current as it charges up. That sounds to me as being behind the problems, but none of those should pop a 10A fuse.

The last possible is the 'ricochet effect' where a pulse at the socket is reflected back to the source and causes another device (like a charger) to react, but that is really clutching at straws, it should be a simple fuse rating issue, and I'd try a 15A fuse and see if that cures the issue.

Peter


----------



## Penquin (Oct 15, 2007)

Just a thought......

if you plugged a splitter or 12v extension lead in WITH THE 12V TURNED OFF but with nothing plugged in to the other end, hopefully the fuse will not then blow when you turn the 12v on (which is more or less what you said but I am suggesting using a 12v splitter rather than direct plugging.....

then if you plug the appliance into the other end of the 12v splitter....

hopefully the fuse will not go this time..... in which case I would ask the dealer to check the sockets as errant tracking and shorts seem to be causing the fuse to blow.....

Just trying to work out how to identify where the fault lies......

Dave


----------



## Grizzly (May 9, 2005)

Thanks all. Until we get home are going to use the work around and be more disciplined about charging en route from the cab sockets. We' ll then be asking about changing the sockets completely and / or changing the fuse size before our next trip. 

. Those who use 10 amp spade fuses can now relax as we are not about to cause a European shortage.

G


----------

