Whilst on a recent trip we lost all power to the caravan lights whilst driving on the motorway. Once stopped at the services and with the AA called out the problem was the grey charging lead had melted inside the socket on the back of the car causing a fuse to blow. The AA man quickly replaced the fuse and the lights ran fine with the grey plug not used. Since our return i have called in at a local towbar fitter and explained the problem - he told me it was an earth burn out and that a simple replacement of the plug and the socket would resolve the problem (at £35). However he said that there was no reason to explain why this problem occured, it just does!!! Anybodys opinion would be greatly received i dont like the thought that this could just occur at any time and i could be left without any lights. The guy also advised me not to use the plastic socket covers as they keep the damp trapped in and cause more harm than good, so again any advice greatly appreciated.
Earth burn out?
- Thread starter leefaz1797
- Start date
Hello Lee,
Clearly it is not possible for anyone on the forum to confirm the fault you may have had, but the fitters description of 'earth burnout' cannot be technically correct, as 12V systems do not have an earth. They do have a negative return which is what he probably meant.
It is well recorded that the pins in the 7N and 7S plugs and sockets do become worn and corroded with time, and as a result the quality of the contact can deteriorate. Watch out especially for teh pins that are bifurcated, as the gap can close a little which reduces the contact quality. This in turn can lead to a high resistance contact. The negative in these plugs carries the combined return current from all the lights etc, so if there is a poor contact it will result in more current generated heat in the contact which can damage the connected cables.
I personally cannot see any difference in the damp retaining properties of either plastic or metal housings, but the plastics may distort more and contribute to poor contacts, and of course being plastic may melt if a contact does over heat,
Two of the most effective solutions I have found is to lightly spray some WD40 (or similar water displacing lubricant) into the plug and socket before each trip. and spread the bifurcations to ensure they have a snug fit in the sockets.
Clearly it is not possible for anyone on the forum to confirm the fault you may have had, but the fitters description of 'earth burnout' cannot be technically correct, as 12V systems do not have an earth. They do have a negative return which is what he probably meant.
It is well recorded that the pins in the 7N and 7S plugs and sockets do become worn and corroded with time, and as a result the quality of the contact can deteriorate. Watch out especially for teh pins that are bifurcated, as the gap can close a little which reduces the contact quality. This in turn can lead to a high resistance contact. The negative in these plugs carries the combined return current from all the lights etc, so if there is a poor contact it will result in more current generated heat in the contact which can damage the connected cables.
I personally cannot see any difference in the damp retaining properties of either plastic or metal housings, but the plastics may distort more and contribute to poor contacts, and of course being plastic may melt if a contact does over heat,
Two of the most effective solutions I have found is to lightly spray some WD40 (or similar water displacing lubricant) into the plug and socket before each trip. and spread the bifurcations to ensure they have a snug fit in the sockets.
Do yourself a favour, convert to the 13 pin system and put all these problems behind you.
Steve W
Steve W
If you do a search on this forum you will find several threads on the subject.Depending on the year of your van and how your car is wired up.Basically you will need a seperate earths for the fridge and the charging circuits so as not to overload the earth cable.As previously stated 13 Pin set up will cure the problem.
If your refering to the center pin in the grey plug,it happened on mine,the centre pin melted the surounding plastic in the van & the car plug, I replaced both & have had no further problems
Tony
Tony
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