Reverse polarity (1 Viewer)

[mojo]

Just spent two nights on a marina campsite in Uphill,Somerset.With the mains plugged in our Sargent supply unit showed up a red light stating reverse polarity.When this happens abroad I use a extra plug that has the wires reversed to bring the supply to normal and the light expires.
On this occasion it remained on ?

Now on a new campsite and all is back to normal.

Does anyone understand what was happening on that one particular campsite ?

 

[JeanLuc]

Could the warning have been caused by a bad earth connection?

I have to say I don't bother about reversed polarity but I usually put a socket tester in the van to check for poor earth.

 

[Traveller_HA5_3DOM]

I have yet to see a camper that has switches on the 13 amp sockets so even with normal polarity the live wire follows right down to your appliance switch. It does stop there but when reversed polarity the whole appliance is live right round to the on off switch. Does it matter? Not if the appliance wiring does not touch something that you can touch in handling it. i.e. it is faulty in some way. The main risk in single live switched sockets as we use in the UK or indeed non switched sockets that campers use is that the plug wiring remains live as long as it is plugged in, so wiring breaks due to the flexing and general handling of the plug can result in you touching live wires.
Does anyone have switched sockets in their motorhome fitted as standard?

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[Deleted member 29692]

Does anyone have switched sockets in their motorhome fitted as standard?

Mine does :Cool:

 

[1_man_and_his_dob(lo)]

Does anyone have switched sockets in their motorhome fitted as standard?

Yes...one double socket and a single.

 

[camocam1]

No switched plugs but I bought switched adaptor for the plugs so we can switch off items if required

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[aba]

At a venue we have done several concerts at the audio mains supply is transformer isolated that brings on all sorts of lights on the distro.

Don't understand how it works but it seems to ok.

 

[pappajohn]

Could the warning have been [HI]caused by a bad earth connection[/HI]?

I have to say I don't bother about reversed polarity but I usually put a socket tester in the van to check for poor earth.

agreed.....this also happens a lot when using a generator.

The normal polarity circuit needs a proper earth and as the generator doesnt have a true earth so sees it as reversed polarity.

insufficient or complete lack of earth is FAR more important than reversed polarity for two reasons.

1...it protects you in an earth fault situation.....it cant if theres no earth

2...protective devices (RCD/RCBO) rely on an earth to work....it cant work if theres no earth.

 

[gasman2008]

English MCB's are on the live circuit, RCD's are on both live and neutral, so if you have reversed polarity, your MCB is not working if you have a short to earth even if it is through you to earth, the RCD may still protect you but not always. If you use your home with reversed polarity you have removed one safety device. For that reason I always deal with the situation using a changeover lead I made. I don't know for sure as I have not worked in France but I have been told that their MCB's work on both live and neutral so reverse polarity not so important, but I take no chances.

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[pappajohn]

alternating current (AC) spends 50% of its time reversed anyway.....

230v+ / 0v / 230v- / 0v / 230v+.....60 times a second

 

[SMB]

I have the Sargent control box in my Swift and the reverse polarity light comes on for that and also no earth. I have a tester which plugs into the internal plug sockets and gives a indication re the electricity supply i.e. no earth etc. Van hasn't blown up yet fortunately...

 

[Clive]

Just spent two nights on a marina campsite in Uphill,Somerset.With the mains plugged in our Sargent supply unit showed up a red light stating reverse polarity.When this happens abroad I use a extra plug that has the wires reversed to bring the supply to normal and the light expires.
On this occasion it remained on ?

Now on a new campsite and all is back to normal.

Does anyone understand what was happening on that one particular campsite ?

You get the same issue with a generator and, so I've been told, it's a lack of earth point that causes it.

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[gasman2008]

alternating current (AC) spends 50% of its time reversed anyway.....

230v+ / 0v / 230v- / 0v / 230v+.....60 times a second

This is not how ac works neutral is just that neutral, the live goes 120 above neutral then 120 below 60 times a second. At no time is any current carried along the neutral. In fact in a PME earth system the earth and neutral are linked.

 

[pappajohn]

This is not how ac works neutral is just that neutral, the live goes 120 above neutral then 120 below 60 times a second. At no time is any current carried along the neutral. In fact in a PME earth system the earth and neutral are linked.

i wondered how long it would take !!!!!!
Just under 2 hours

I work with the stuff for a living. :thumb:

 

[Techno]

They are only linked at source before the RCD or RCBO
If you put the neutral to earth or anywhere else outside of the circuit it will immediately trip the device. The most important thing is to test the device operates every time you set up somewhere new. Polarity is irrelevant unless you're going to open things up and meddle with live wires.

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[Voyger1010]

If it was a marina that you were camping at, and using their EHU , then it is probably an earth fault. Marinas are renowned for the problem with the main electric supplies and poor earth connections. In a number of marinas I have visited over the years with the boats there has been this problem which also causes galvanic corrosion via stray electrical currents.
Given what you've reported, when you got back to your normal site hook up and that all was well, I certainly would worry about reversing polarity devices. Hope it helps

 

[scotjimland]

This is not how ac works neutral is just that neutral, the live goes 120 above neutral then 120 below 60 times a second. At no time is any current carried along the neutral. In fact in a PME earth system the earth and neutral are linked.

first of all, the frequency in the UK is 50hz.. not 60

and the neutral conductor in an AC circuit carries the exact same current as the live ..

if you don't believe, me try a tong tester on your Live and Neutral on your domestic supply ..

if that was imbalanced it would trip the main ELCB

NO current flows in the Earth unless their is an earth fault .. which as said.. would trip the ELCB

 

[Puddleduck]

Okay, continuing with the thread I've been told that we have a double pole (I think - it was getting a bit too technical at this point) MCB and were told that protected in some way. Is this correct and we don't have to worry about reversed polarity?

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[JeanLuc]

I think most continental vans have double-pole isolation.
Also, many appliances today are double-insulated - enhanced safety but never let water get into the 'gubbins'.
http://www.plugwiring.co.uk/plug-wiring-posts/double-insulated-appliances-no-earth-wire/

And many items are double-pole switched (even some of our table lamps at home) so both '+' and '-' sides are switched.

 

[andy63]

hi puddleduck, I think the reference to double pole just means the switching isolates both the live and neutral lines at the switch..
it seems to be generally agreed that as long as you are not going to be working on live appliances in your motorhome then its not really an issue.
I run a generator to charge my batteries and the tester would indicate a fault but all works ok.
discussions on the subject always get quite technical but I always enjoy reading peoples views on the subject.
regards andy

 

[Traveller_HA5_3DOM]

Mine does :Cool:

Yes...one double socket and a single.

Do you know if the switch works on both the live and neutral poles? If it does then it will switch off the live even when the polarity is reversed.

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[Deleted member 29692]

Not sure if mine are double pole or not but I would be inclined to doubt it. I will check and report back :thumb:

 

[pappajohn]

your main protection is not the MCB's....they are an overload device.....plug in a 15 amp appliance into a 10 amp socket and it will trip

The main protection is the RCD main switch..... if it has a test button on it, if it hasnt then its just an on/off switch and offers no protection.

In the event of a fault it will trip and all power into the van is disconnected.....and it will wotk in a reversed polarity situation.

Again....this RCD protective device will only work if an earth is present.

 

[jonandshell]

This all sounds a bit dodgy to me!

Its a good job we haven't used hookup for over 2 years!

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[Steve]

agreed.....this also happens a lot when using a generator.

The normal polarity circuit needs a proper earth and as the generator doesnt have a true earth so sees it as reversed polarity.

insufficient or complete lack of earth is FAR more important than reversed polarity for two reasons.

1...it protects you in an earth fault situation.....it cant if theres no earth

2...protective devices (RCD/RCBO) rely on an earth to work....it cant work if theres no earth.

A good reply from pappajon:thumb:
and all my sockets are switched