I know I've said this before - but before I used these Forums I had no idea about 'Reverse Polarity' and therefore took no precautions of 'tester' or 'reversed connectors', just hooked up and carried on. I just wonder whether it is a real and actual danger, in which case you'd think French campsites would be required to display a warning, or whether it is just one of those things that we (or some of us) go on doing, because we're told to - or because someone else does it! Has ANYONE actually had problems - and if so what?
Hello Valerie,
Reverse polarity in caravans does not generally cause a problem, In fact most appliances will work quite happily. The problem arises when an appliance become faulty.
In the UK, if you switch an appliance off, then you expect that the live circuit is properly broken, and so no power will be entering the appliance. This is because the switch is in the live feed. However, for many years and still to-day some appliances only disconnect the live feed, leaving the neutral conductor fully connected.
Now if such an appliance is connected to a reversed polarity feed, then whist the control switch breaks the circuit, the in coming live feed is connected to the appliance neutral conductor, which means that parts of the appliance may still be LIVE even though the switch is off! This is not really a safe situation.
The power switch in most continental equipment are double pole and acts on both Live and neural wires so the polarity of the power supply is not a problem, but where on some UK made equipment the power switch only disconnects the Live feed wire, there might be a problem
Most modern caravans use double pole isolators, and equipment manufacturers are encouraged to use double pole switching, so reversed polarity is not generally a problem.
Reverse polarity in caravans does not generally cause a problem, In fact most appliances will work quite happily. The problem arises when an appliance become faulty.
In the UK, if you switch an appliance off, then you expect that the live circuit is properly broken, and so no power will be entering the appliance. This is because the switch is in the live feed. However, for many years and still to-day some appliances only disconnect the live feed, leaving the neutral conductor fully connected.
Now if such an appliance is connected to a reversed polarity feed, then whist the control switch breaks the circuit, the in coming live feed is connected to the appliance neutral conductor, which means that parts of the appliance may still be LIVE even though the switch is off! This is not really a safe situation.
The power switch in most continental equipment are double pole and acts on both Live and neural wires so the polarity of the power supply is not a problem, but where on some UK made equipment the power switch only disconnects the Live feed wire, there might be a problem
Most modern caravans use double pole isolators, and equipment manufacturers are encouraged to use double pole switching, so reversed polarity is not generally a problem.
Then doesn't this equally apply when we plug British equipment (hairdryers, irons, laptops, etc) into normal 'French' sockets using an adaptor. No-one suggests you should take a 'polarity tester' with you when staying in French hotels - and if not, why not?
How can I determine if I have a live/neutral reversal if I don't have a plug in detector? Can I detect it with a multimeter? If so how ?
George
George
George
Set the meter to a setting above 240 V on an ac setting (normally 250 or 300V ac, connect the black lead to a local earth - most distribution poles will have one / if metal the pole will make an adequate earth / bang a piece of steel into the ground.
Do not touch any connectors with anything other than the probes.
Using the red lead, the neutral feed reading should be close to 0 V and on the live feed close to 230V, if the other way around it is reversed.
I can not quote colours in Europe as I only have electrical experience in the UK, but electrical principles do not change with borders.
Set the meter to a setting above 240 V on an ac setting (normally 250 or 300V ac, connect the black lead to a local earth - most distribution poles will have one / if metal the pole will make an adequate earth / bang a piece of steel into the ground.
Do not touch any connectors with anything other than the probes.
Using the red lead, the neutral feed reading should be close to 0 V and on the live feed close to 230V, if the other way around it is reversed.
I can not quote colours in Europe as I only have electrical experience in the UK, but electrical principles do not change with borders.
Thanks Garry,
I should have been able to work that out for myself, brain rot...doh.
Just realised I can use my little light up screwdriver, a lot less hassle.
Thanks
I should have been able to work that out for myself, brain rot...doh.
Just realised I can use my little light up screwdriver, a lot less hassle.
Thanks
Actually no. The RCD does not have an earth connection so it is impossible to leak some power to earth by pressing the test button.
What it actually does is connect a small resistor from the live outlet of the RCD to the neutral inlet of the RCD. Then there will be a small current flowing in the live through the RCD that is not flowing in the neutral, an imbalance occurs, and the RCD will trip.
What it actually does is connect a small resistor from the live outlet of the RCD to the neutral inlet of the RCD. Then there will be a small current flowing in the live through the RCD that is not flowing in the neutral, an imbalance occurs, and the RCD will trip.
Hello again Valerie,
My previous reply was related to caravan electrical systems, where the systems and fixed appliances in a modern caravan should all be double pole switched.
However the jist of my reply is still relevant to portable appliances such as hair dryers etc. Provided the appliance is not faulty, then it will most likely work quite satisfactorily, however as soon as you switch it off, you cannot gurantee that the insides of the appliance will be disconnected from the live supply, so there is a potential hazard. IN all cases it is wise to totally unplug portable devises from mains supplies to ensure complete disconnection from the supply.
The other danger is, that if the appliance develops a fault, then despite the fuse blowing or other normal UK safety devices operating, the appliance may still be Live.
It could be a sensible choice to test your forign sockets before plugging in UK electrical products.
Please do not get the impression that all appliances will be dangerous, It all depends on the method of construction, and to what standard the appliance has been manufactured. BUT unless you know and can identify the differences, it is wise to assume and use the safest approach possible. - Unplug
My previous reply was related to caravan electrical systems, where the systems and fixed appliances in a modern caravan should all be double pole switched.
However the jist of my reply is still relevant to portable appliances such as hair dryers etc. Provided the appliance is not faulty, then it will most likely work quite satisfactorily, however as soon as you switch it off, you cannot gurantee that the insides of the appliance will be disconnected from the live supply, so there is a potential hazard. IN all cases it is wise to totally unplug portable devises from mains supplies to ensure complete disconnection from the supply.
The other danger is, that if the appliance develops a fault, then despite the fuse blowing or other normal UK safety devices operating, the appliance may still be Live.
It could be a sensible choice to test your forign sockets before plugging in UK electrical products.
Please do not get the impression that all appliances will be dangerous, It all depends on the method of construction, and to what standard the appliance has been manufactured. BUT unless you know and can identify the differences, it is wise to assume and use the safest approach possible. - Unplug
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