Polarity
Comments
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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?).
Recommended practice for caravans is double pole breakers and all the ones that I have seen do have these fitted. Also it is usual not to have switches on socket outlets. Although this may be for cost saving it has the hidden benefit that you have to take the plug out to isolate the circuit hence overcoming the basic issue with RP (the isolation problem).
It is correct that with no Earth at the EHU the caravan metal work could be live and the fault not clear so it is dangerous if you go outside of the caravan (Because you can create a circuit just by standing on the ground). Within the caravan, if you touch live and there is any kind of decent earth path then the rcd will operate. If there is no earth in the van then in theory you can't get a shock between live and metal, only live and neutral. Generally I imagine that there will be some kind of earth path through the steadies etc.
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Pleased we agree. C.Eng , but only an M not an F (and it will always be IEE to me, not T
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Pleased we agree. C.Eng , but only an M not an F (and it will always be IEE to me, not T
).Glad to see a fellow professional. I hate mentioning my professional qualifications but the other poster was giving totally incorrect and hence bad information. The final straw was being told to Google it! He/she probably believes everything they read in
Wikipedia as well.0 -
Polartity - it's big, it's white and, if there aren't any seals around, it will eat you.
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Pleased we agree. C.Eng , but only an M not an F (and it will always be IEE to me, not T
).Glad to see a fellow professional. I hate mentioning my professional qualifications but the other poster was giving totally incorrect and hence bad information. The final straw was being told to Google it! He/she probably believes everything they read in
Wikipedia as well.For someone who hates mentioning their professional qualifications you mention them quite a lot,
You've mentioned you worked at the IET at least 2 other posts.
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Pleased we agree. C.Eng , but only an M not an F (and it will always be IEE to me, not T
).Glad to see a fellow professional. I hate mentioning my professional qualifications but the other poster was giving totally incorrect and hence bad information. The final straw was being told to Google it! He/she probably believes everything they read in
Wikipedia as well.For someone who hates mentioning their professional qualifications you mention them quite a lot,
You've mentioned you worked at the IET at least 2 other posts.
Sorry if I offended you but would you rather be given technical advice by somebody who just googled it or by somebody who is actually qualified to give that advice? Given the amount of erroneous, missleading and sometimes dangerous advice given on this forum
and other Internet sites it seems quite reasonable to me for people to state their experience/qualifications so that others can judge whether to accept that advice and possibly act on it.0 -
Pleased we agree. C.Eng , but only an M not an F (and it will always be IEE to me, not T
).Glad to see a fellow professional. I hate mentioning my professional qualifications but the other poster was giving totally incorrect and hence bad information. The final straw was being told to Google it! He/she probably believes everything they read in
Wikipedia as well.For someone who hates mentioning their professional qualifications you mention them quite a lot,
You've mentioned you worked at the IET at least 2 other posts.
Sorry if I offended you but would you rather be given technical advice by somebody who just googled it or by somebody who is actually qualified to give that advice? Given the amount of erroneous, missleading and sometimes dangerous advice given on this forum
and other Internet sites it seems quite reasonable to me for people to state their experience/qualifications so that others can judge whether to accept that advice and possibly act on it.Seems you are implying I am not qualified to give advice on this forum H G, well firstly I didn't need to Goolgle the topic. I have had 50yrs plus in the electrical trade , both practicle and technical. Also as supervisor , and electrical inspector,
so I think I do know a little about electrical problems. I might add in the electrical trade Cross Polarity is taboo and you, with your statedexperience should not be condoning it. Now as I tried to state earlier I do not wish to continue our conversation on this topic So please in the future get your facts Correct .
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