Reversed polarity, is it an issue?

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Travelling Westerly

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Just got into a new marina (France), plugged my shore cable in and turned on my 240v appliances, so far no issue...

However I noticed my 240v panel polarity lights are saying my polarity supply is incorrect?

Everything is working fine, my last stop a couple of days ago in another French marina showed the supply polarity was correct. Since I've not done any electrical work at all since my last stop it's not a problem I've manufactured.

Questions are, is it dangerous, is it worth me changing over my N and L wire in my shore supply plug, can I test the marina supply for polarity with a multimeter to confirm its definitely the issue?

Thanks
 
Cornishwesterly said:
Just got into a new marina (France), plugged my shore cable in and turned on my 240v appliances, so far no issue...

However I noticed my 240v panel polarity lights are saying my polarity supply is incorrect?

Everything is working fine, my last stop a couple of days ago in another French marina showed the supply polarity was correct. Since I've not done any electrical work at all since my last stop it's not a problem I've manufactured.

Questions are, is it dangerous, is it worth me changing over my N and L wire in my shore supply plug, can I test the marina supply for polarity with a multimeter to confirm its definitely the issue?

Thanks
Click to expand...
Don't know about France, but in UK it's easy to get a simple polarity 13a test plug. I know because when I bought my present boat, something I did, gave me a slight shock. It turned out that the US of A shore connection plug was wired wrongly. Hence the test plug aboard.
 
Cornishwesterly said:
Just got into a new marina (France), plugged my shore cable in and turned on my 240v appliances, so far no issue...

However I noticed my 240v panel polarity lights are saying my polarity supply is incorrect?

Everything is working fine, my last stop a couple of days ago in another French marina showed the supply polarity was correct. Since I've not done any electrical work at all since my last stop it's not a problem I've manufactured.

Questions are, is it dangerous, is it worth me changing over my N and L wire in my shore supply plug, can I test the marina supply for polarity with a multimeter to confirm its definitely the issue?

Thanks
Click to expand...

Most things should work, but not usually a good idea. Unless you have dual pole circuit breakers you will have the negative "fused". A fault in a appliance could leave it live.

Usual thing would be to carry a short shore power cable (1 metre would be plenty) with the polarity reversed in one of the connectors.
 
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PaulRainbow said:
Most things should work, but not usually a good idea. Unless you have dual pole circuit breakers you will have the negative "fused". A fault in a appliance could leave it live.

Usual thing would be to carry a short shore power cable (1 metre would be plenty) with the polarity reversed i one of the connectors.
Click to expand...
This is exactly what we do - carefully marked and we use a simple plug in polarity tester from B&Q as we don’t have AC on a panel. Happens every now and again in Europe,
 
PaulRainbow said:
Most things should work, but not usually a good idea. Unless you have dual pole circuit breakers you will have the negative "fused". A fault in a appliance could leave it live.

Usual thing would be to carry a short shore power cable (1 metre would be plenty) with the polarity reversed i one of the connectors.
Click to expand...
Thanks Paul, great advice as always. Im here for another week before moving on so might as well just swop the wires over in my socket that goes into the supply tower on the pontoon.

Presumably its no more complicated than that?
 
Cornishwesterly said:
Just got into a new marina (France), plugged my shore cable in and turned on my 240v appliances, so far no issue...
However I noticed my 240v panel polarity lights are saying my polarity supply is incorrect?
Everything is working fine, my last stop a couple of days ago in another French marina showed the supply polarity was correct. Since I've not done any electrical work at all since my last stop it's not a problem I've manufactured.
Questions are, is it dangerous, is it worth me changing over my N and L wire in my shore supply plug, can I test the marina supply for polarity with a multimeter to confirm its definitely the issue?
Thanks
Click to expand...
The danger comes from the fact that UK appliances and switched sockets usually have single pole switching ie only the "line" is switched. If the supply has its polarity reversed your switches will only be switching the "neutral" meaning the the insides of things will be live when the switch is "off"
Dont mess with the insides of things unless they are completely unplugged.
Your RCD/RCBO should still offer you the normal protection against electrocution provided it is a 2 pole device.

You can swap the L & N ( I don't think I would bother if the RCD is 2 pole), but want you really need is a short polarity reversing adapter lead that you can use when you meet this situation.

Yes you can check the supply polarity, if you must, using your meter on its highest AC volts range. Measure between the "earth" conductor and each of the supply conductors in turn. The "line" will read the full supply voltage. The "neutral" should read 0 .............. but take care doing this ! but you know its reversed ..... you panel lights are telling you that it is
 
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dankilb said:
Isn’t that the issue/problem - because most boat installs with domestic CUs only include single pole RCDs?
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I think what you have to be wary of are CUs with single pole RCBOs which disconnect what is normally the "line" conductor but is of course only the "neutral " if the supply polarity is reversed, leaving the unwary to the full effects of electrocution.
If RCBOs are fitted in a situation where reversed polarity of the supply may be encountered they must be double pole

The "garage" consumer units with a 2 pole RCD and a couple of ( single pole ) MCBs may not be so bad in so far as an earth leakage fault or contact with the "line" conductor, will disconnect both line and neutral which ever way the supply is polarised and so prevent electrocution , but the single pole MCBs still present a problem.
 
VicS said:
The danger comes from the fact that UK appliances and switched sockets usually have single pole switching ie only the "line" is switched. If the supply has its polarity reversed your switches will only be switching the "neutral" meaning the the insides of things will be live when the switch is "off"
Dont mess with the insides of things unless they are completely unplugged.
Your RCD/RCBO should still offer you the normal protection against electrocution provided it is a 2 pole device.

You can swap the L & N ( I don't think I would bother if the RCD is 2 pole), but want you really need is a short polarity reversing adapter lead that you can use when you meet this situation.

Yes you can check the supply polarity, if you must, using your meter on its highest AC volts range. Measure between the "earth" conductor and each of the supply conductors in turn. The "line" will read the full supply voltage. The "neutral" should read 0 .............. but take care doing this ! but you know its reversed ..... you panel lights are telling you that it is
Click to expand...
Appreciate your help, great thing about this forum is the help one can get even on xmas day!

Thanks very much to all posters, help greatly appreciated
 
PaulRainbow said:
Usual thing would be to carry a short shore power cable (1 metre would be plenty) with the polarity reversed in one of the connectors.
Click to expand...
I do the same, but I would suggest (150mm) to keep the plug & socket off the ground. Which is what I have.
Having a 50 metre , 4 socket,cable reel I keep a circuit tester in one of the sockets as suggested earlier. That way I never plug in to the boat until I know that the supply is live & the polarity & earthing is OK. I know some dislike cable reels, but I do not use enough power to need to unroll the full reel every time.
 
Sorry to sound like a dill, but are we talking about AC (Alternative Current) here?
If so, how is reverse polarity identified and why would one marina be different from another?

gary
 
westernman said:
RCD certification requires double pole RCDs.
Click to expand...
This discussion reminded me that our plan (ahead of a complete rewire) was to fit a double pole RCDO where the shore power enters. It’s then a long run to the CU (and after a Multiplus II) so the logic was to protect that cable run. I’ve already build the CU with regular single pole MCBs. The logic for an RCDO over RCD was to trip at 16A, before the bollard (for ‘convenience’ rather than safety per se). I’m not a complete electrical numpty - I hope! - but will try to get it checked by a competent person mate if I can.
 
garymalmgren said:
Sorry to sound like a dill, but are we talking about AC (Alternative Current) here?
If so, how is reverse polarity identified and why would one marina be different from another?

gary
Click to expand...
Because in France, where I live, both supply and return (live and neutral) cables are fitted with breakers, as VicS has explained. Consequently far less attention is paid to ensuring that the live cable is always the red one, as in UK. In my house many sockets and lights have reversed polarity but touching any of them results in breaking the circuit, as both lines are protected.

There is a convention that the live wire goes to the right hand connection but no plugs and sockets that I buy are marked as such, as they would be in UK.

When I wired my boat for mains I ensured that the RCD breaker was dual circuit, as it was always going to be in Europe.
 
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