# 240v fuse blowing



## lipupfatty (Sep 3, 2008)

Greetings All, I wondered if having a flat engine battery could cause the 240v fuse to blow. I connected up the external lead from my house to the van to charge the battery ,but keeps blowing the fuse in my house. I think the lead is OK as only blows when connected to the van.


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## rosalan (Aug 24, 2009)

I cannot think of how a flat van battery can have any effect upon the 240v mains input. However, as you for some reason think it may do, disconnect the battery from both poles to eliminate it. after first disconnecting the hook-up lead from the van and testing that all works well up to that point. With the power off, re-connect the hook-up lead and try again.
If it still blows, go to the vans input fuse box and switch off all circuits and test again. until, by elimination you are able to determine which circuit is causing the fuse to blow. There are not too many areas to concern yourself with.
As you have a Hymer van, it could be the (Schaudt ?) control unit, the fridge or one of the power sockets that may be in use. It is a process of elimination.

Alan


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## onnilucky (May 21, 2013)

Is it the 240V fuse blowing or a trip that is switching off.


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## lipupfatty (Sep 3, 2008)

It's the trip thats going.
Nothing switched on in the van, and been perfectly OK until today.The only reason that I thought that it may be the engine battery is that because it is flat there will be a large current initially before it backs off. Don't really know what I'm talking about, hence asking for assistance.
When I switch on the 12v all appliances are fine.
The trips are rated correctly as have been used on numerous other domestic occasions.


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## Bigusdickus (Nov 6, 2012)

Try another lead. A fuse or trip switch is intended to protect a cable.
Bd..


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## lipupfatty (Sep 3, 2008)

Thanks, did think about trying another lead but don't have one.
Also it doesn't trip when not connected to the van, so assumed the lead must be OK.


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## cabby (May 14, 2005)

If you had your location showing with your avatar we could see if anyone was close enough to lend you a cable to try.

cabby


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## TerryL (Feb 19, 2009)

I'm no electrician but as it's blowing when connected but ok when not I would strongly suspect the connector plug. A wire could have become loose in the plug and as I understand it that would cause the trip to function - they only need a tiny fault to blow.


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## rayc (Jun 3, 2008)

I may be confused but is an MCB or RCB that is tripping?


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## Bigusdickus (Nov 6, 2012)

It's unlikely, but possible, to be a flat battery or charger causing this problem. I think you still need to get the lead tested to PAT standard. When only the lead is plugged in there is no current flowing. As stated current flows on load demand but voltage is always present. Can you put an additional load on the lead without connecting it to the van? Do you have any neighbours with a caravan so you can borrow theri lead to try? Could there be damp in the van connector? 
MCB = miniture circuit breaker - modern substitute for fuse
RCD = residual current device - monitors for current leakage and trips out on imbalance... ie what comes in the red wire should go out through the black, if it doesn't then it's gone somewhere else.
If a fuse is blowing there's obvioulsy a short circuit somewhere. If you're sure the van fuseboard is totally isolated and it's still happening you could cut 1 foot off the lead at one end and remake the connections and try again. Also, if you're confident with tools disconnect the feed into the van fuseboard then plug the lead in again but ******* the wire will be live********* so be carefull and keep the wife and kids away and only do it for a couple of seconds, then disconnect again. 
***ALWAYS BE CAREFUL WITH MAINS VOLTAGES***
Bd..


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## lipupfatty (Sep 3, 2008)

Thanks to all who replied.
It was the engine battery causing the problem, improbable maybe-impossible no.
The battery should have charged to 980en but would only hold 78en so was totally useless.
Due to the huge initial charge being drawn , it was tripping the RCD in the house.
Replaced the battery and everything is fine.
Just proves the point, - do not discount anything, however unlikely if it could be at all possible.


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## Bigusdickus (Nov 6, 2012)

Glad you're sorted.
I'm surprised that your flat battery didn't pop a circuit breaker in the van on the charger as there should be one on the output side to protect it, this should have happened. But it goes to show that the circuit breaker in your house is more sensutive than the van.
I live and learn.
Bd..


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## Penquin (Oct 15, 2007)

Thanks for the update, glad that it has been sorted, circuit breakers can be VERY sensitive for good reason.....

I think the domestic ones are more sensitive than the ones in MH......

Dave


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## hanray (Feb 2, 2011)

*sensitive RCD*

Your flat battery could trip your house electrics for two reasons. If the battery has failed internally, you could get a direct short which will trip the RCD. If your battery charger spikes when turned on, the sensitive RCD will ping first.
As we have just had probably the first cold snap of winter and your battery is now flat, provided you haven't left any lights etc turned on, your probably best to change the battery anyway, especially if it's 5 years old or more.
I trained as a vehicle mechanic when God was a boy so the following is what I would do. 
If you are not confident - Don't !
May I also suggest disconnecting both terminals from the battery, earth first (to prevent any possible damage to the camper electrics). Connect the charger to the battery. If it still trips the RCD you could try the following.
Find a 12 volt light bulb (indicator bulb will do nicely). Connect the battery charger earth (black) crocodile clip around the bulb and touch the other (red) crocodile clip to the end of the bulb. If the bulb lights, your battery charger and extension lead are ok and the battery is faulty. If the RCD ping's, your fault is with either the charger or extension lead. Plug the charger directly into the house electrics without the extension lead and try again with the 12 volt light bulb. If the light lights, it's the extension lead which is faulty, if the RCD ping's, it's the charger at fault. You could also try another house socket - just in case!
Hope this helps
Regards
Ray


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## kenny (Jun 4, 2005)

*fuses*

with the mains turned off disconnect the charger unit turn the power back on if it does not blow the fuses you know it is the charger had problems with mine the capacitors had burnt out, to test your lead unplug it from the van plug into the mains if all is ok you know its on the van i would say the charger is faulty kenny


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