Polarity

The user and all related content has been Deleted User

Polarity is a big problem! If polarity is reversed then the Nuetral pole becomes the live pole. If this occurs then this now live pole has no fuse protection , this means any fault will result in heating and melting of the cable and possible fire, because of non fuse protection.

obviously if reverse polarity is present and no faults are evident then it will behave as if there isn't any problem. But Do you want to take the Risk?

Not true. Overcurrent flows through both conductors and the fuse still blows.

The ONLY potential issue with RP is that if you switch off a plug or an appliance then it may still be live. If you pull the plug out before poking around then it's fully isolated.

Why are the experts getting so bogged down with this?

Does your caravan / motorhome electrical system have a RCD fitted - IF NOT, FIT ONE!  use the test button when you connect up to the EHU. If it trips then the RCD will do its job and operate should a earth fault / single phase overload occur. 

Using a martindale will give you peace of mind, but any test equipment that you use should be tested and callibrated  on a regular basis to prove that it's functioning safely.  Getting the vehicle electrically tested on a regular basis isn't a bad idea as well. It might help to put this worry to bed and let you sleep soundly!

An RCCB does not protect against over load or short circuit current. Only protects on earth leakage so cross polarity is not protected. It could be that EU countries still use the duel fusing system , where both phase and neutral are fused. In this country now only the live phase is fused , the nuetral being a solid bar ( unfused  ) . I still say do what you want,  but my earlier post makes sense,

believe me !!

It’s quite simple really, and this is why I always use one.

If polarity is not a safety issue and a RP tester/cable is used then there is no harm done and all remains safe.

If reversed polarity is a safety issue and the RP tester/cable is not used and something happens, then.......

It’s quite simple really, and this is why I always use one.

If polarity is not a safety issue and a RP tester/cable is used then there is no harm done and all remains safe.

If reversed polarity is a safety issue and the RP tester/cable is not used and something happens, then.......

 Quite right Bewick, it is a safety issue., but some people ignore good advice. They think it will never happen to me and sometimes it does.

An RCCB does not protect against over load or short circuit current. Only protects on earth leakage so cross polarity is not protected. It could be that EU countries still use the duel fusing system , where both phase and neutral are fused. In this country now only the live phase is fused , the nuetral being a solid bar ( unfused  ) . I still say do what you want,  but my earlier post makes sense,

believe me !!

Sorry to be pedantic but the reason these threads go on for so long is that people post incorrect statements or repeat what has already been said. Current can only flow in a complete circuit of live and neutral. So, if your circuit takes excessive current the fuse or overload protection (mcb) will trip irrespective of whether it is in the live or neutral. It is not helpful to post technically incorrect information and it makes things even more complicated. I repeat, RP is an isolation issue, nothing else.

An RCCB does not protect against over load or short circuit current. Only protects on earth leakage so cross polarity is not protected. It could be that EU countries still use the duel fusing system , where both phase and neutral are fused. In this country now only the live phase is fused , the nuetral being a solid bar ( unfused  ) . I still say do what you want,  but my earlier post makes sense,

believe me !!

Sorry to be pedantic but the reason these threads go on for so long is that people post incorrect statements or repeat what has already been said. Current can only flow in a complete circuit of live and neutral. So, if your circuit takes excessive current the fuse or overload protection (mcb) will trip irrespective of whether it is in the live or neutral. It is not helpful to post technically incorrect information and it makes things even more complicated. I repeat, RP is an isolation issue, nothing else.

If you don't believe me then Goggle it . Enough said now so carry on being unsafe.

An RCCB does not protect against over load or short circuit current. Only protects on earth leakage so cross polarity is not protected. It could be that EU countries still use the duel fusing system , where both phase and neutral are fused. In this country now only the live phase is fused , the nuetral being a solid bar ( unfused  ) . I still say do what you want,  but my earlier post makes sense,

believe me !!

Sorry to be pedantic but the reason these threads go on for so long is that people post incorrect statements or repeat what has already been said. Current can only flow in a complete circuit of live and neutral. So, if your circuit takes excessive current the fuse or overload protection (mcb) will trip irrespective of whether it is in the live or neutral. It is not helpful to post technically incorrect information and it makes things even more complicated. I repeat, RP is an isolation issue, nothing else.

If you don't believe me then Goggle it . Enough said now so carry on being unsafe.

If you believe the Internet you are seriously misguided. If, like me, you are a Chartered Engineer, a Fellow of the Institution and have served on the Wiring Regs committee I might take your comment seriously. You are clearly not qualified and have either misunderstood your research or have just read incorrect information. Please do not make things worse and mislead others by insisting you are correct. By the way, I did not say the RP is safe otherwise all the manuals and Club advice would be wrong. It CAN be unsafe under certain conditions where you start messing around with appliances. If you fully understand the dangers then it can be perfectly safe, if not, follow the advice and make up a reversing lead.

In all of the multitude of discussions on 'reversed polarity' I have seen little mention of whether the circuit breakers in the 'van are single pole (as normal in a house) or linked-dual-pole.

My 2005 Elddis has dual-pole breakers and I rather assumed that this would be the norm for all new caravans? This removes all concerns related to overcurrent protection in 'reverse polarity' situations.

The only remaining issue is then someone touching a 'live' part of something they think they have switched off. Even then, the RCD should protect them from anything fatal.

I do agree that a greater concern is the possibility of no earth connection via the EHU cable, either because of a cable fault or because there is no earth at the bollard. The risk then is that under a fault condition the caravan chassis could become live. Even then  I would be quite surprised if there was not enough leakage via the tires/steadies/etc for the RCD to trip. (perhaps we should bond the steadies to  electrical earth and not use insulated feet?).