- Jun 17, 2018
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As I stated my caravan is on my drive should I keep it hooked up to the house for safety reasons like the fridge and keep battery topped up what are your thoughts on this ?
Raywood said:When we had the caravan at home I connected the caravan up to the mains from time to time to charge the battery using a converter for the 13 amp house mains plug. The battery does not need to be on a continuous charge so an external hook up is not needed.
bertieboy1 said:Don't understand this - what "safety" reasons are being considered here.
Our van is alongside the house but not permanently connected to any mains supply.It seems like a waste of power to keep the van powered up from the mains all the time....
ericmark said:I connect to garage supply, normally fridge left running until got around to empting it, caravan is used as an extra room. However safety wise there are a few considerations.
1) Should a battery have a shorted cell it could damage the charger and if not realised could explode, think unlikely but it could happen.
2) If following IET regulations the supply to caravan should be TT, however I have not bothered, it has a TN-c-s supply which technically does not comply.
As an electrical engineer I think on balance better connected to a supply, than not, however it is not correct if I followed regulations.
ericmark said:Supply to boats, caravans and petrol stations are not allowed to be TN-C-S as under fault conditions the earth supplied from the DNO (company supplying electric which may not be billing agent) may not be true earth, C = combined S = Separated so for part of the cable run to your house the earth and neutral is combined but by time it reaches your house separated again. Although TN-S is allowed we have no control so the DNO could change it without notice.
As on a caravan site the posts supplying power have an earth rod for the earth, and fire regulations means buildings have to have some distance between them and the caravan.
Problem at home is the caravan can be close to the house, so having a different earth system could cause danger, as items earthed to house could have a different voltage to that of the caravan, so there is just as much danger having different earthing system as having both house and caravan with TN-C-S system. This has be recognised with electric cars so at home supplies to electric cars has become a specialist subject.
The ultra save method would be an isolation transformer, however most battery chargers are fitted with isolation transformers and are often a Class II supply (no earth connected) so the most cost effective way would be a battery charger with a 13 Pin socket plugging into the caravan car plug so only a 12 volt supply.
However I want to run fridge and central heating in the caravan so fridge is cold before we set off and caravan has had chance to dry out, so I break the rules and plug caravan into the garage. I feel the risk is very low, so I use the TN-C-S supply, as caravan is not lived in at home and access is from a paved area so very unlikely we would ever access under fault conditions and even if we did the paving would offer some protection, and really too close to garage to have a different earth system.
Gafferbill said:.........I put my faith in a residual current curcuit breaker rather than paving slabs :lol:
GD485 said:Ericmark.
You have made me think! So there is a real danger of electric shock from a caravan if there is two separate faults occurring at he same time. i.e. the lose of the earth connection via the hook up cable and an earth fault within the caravan. The body of the caravan could become live assuming there isn't an earth circuit created by the legs in contact with the ground making a good earth (plastic stacker feet).
Unlike a house where the services provide a secondary earth connection along with the rising main amour . An RCD would be useless in this situation as the live and neutral currents would be in balance.
So, should we have an earth rod stuck in the ground and lashed to the caravan chassis?
Surely this could result in "our' earth connection becoming the principle earth point for the locallity and could be subject to enormous earth currents. The isolating transformer and local earth point is the solution as used shore side on boats.