Reversed polarity, is it an issue?

[PaulRainbow]

I agree it is not good practice and greatly reduces safety, just like choosing not to ware a life jacket on a sunny day in harbour, its all down to assessing the risk and making an educated decision.

If it isn't good practice and greatly reduces safety, why did you say :

"what I would do as an electrician.
If I turn up late at a marina and find the polarity is reversed, I would still put the kettle on and plug the fan heater in BUT I would be aware and would explain to my crew that If something stopped working don't assume it is isolated and safe as you might at home, treat it as if it were still live."

Seems pretty irresponsible to me.

In response to Rainbow as he seems to have a problem with any posts I put on this forum-

I only have a problem with people posting incorrect, dangerous or poor advice, if you do that, expect a response.

Complacent or educated, personally as caravans have been required to have double pole mcbs for the last 2 editions of BS7671 and through out the Electrical industry it has not been acceptable to open a cupboard door with no tool and access 230v terminals for as long as I can remember, it isn't acceptable to have unshielded 12v terminals right next to 230v terminals. If you are happy with this arrangement and continue to do such dangerous and shoddy work perhaps you should do a few courses and up your game a bit perhaps you should stick to what you are good at? Criticism!

I don't see where any of that is relevant to your potentially dangerous advice, or the incorrect advice that only double pole MCBs should be used on a boat.

Current standards for new build boats do not require double pole MCBs. I don't build new boats, so i am not required to work to current marine standards, or any other standards, because none are mandatory for electrical installations on "used" boats. However, all of my work does comply with all current standards, as if i was working with a new build.

I commented that many boats have DC and AC components in the electrical "cabinets", which they do, they were built like that by the manufacturers. Provided specific conditions are met, this is in compliance with current requirements.

I did not mention " unshielded 12v terminals right next to 230v terminals", you invented that.

I am happy to work to all of the current standards, not sure how that makes my work "dangerous and shoddy". I can see, however, that your suggestions are indeed dangerous, as can anyone else reading this thread.

 

[Graham376]

I have to agree with Peter, using appliances when you know the polarity is reversed isn't good practice. Just carry a suitably marked cross over cable, sorted!

Not good practice I know but I no longer worry about reverse polarity. Although most marinas are fine, the yard we haul out in is connected by 2 pin plug. Even if I ask them to swap over, every Euro socket on the boat is 2 pin (with no earth pin) so there's always a 50/50 chance of reverse polarity on anything I plug in. The earth contacts for 15 amp plugs are on the sides of the plugs but, small appliance plugs don't have an earth. Instead of just tripping an mcb if I want to work on the wiring, I have a double pole isolator immediately after the deck socket or, unplug shore lead.

 

[PeterWright]

Sorry if I offended you, my intention was to express what I would do as an electrician.
If I turn up late at a marina and find the polarity is reversed, I would still put the kettle on and plug the fan heater in BUT I would be aware and would explain to my crew that If something stopped working don't assume it is isolated and safe as you might at home, treat it as if it were still live.
If I were there for a few days I would make up a lead to correct the polarity or I would swap the wires in my plug making sure I swapped it back after!
Perhaps working with electronics for the last 40years has given me a slightly different approach to it than you, that's fine we all have different levels of risk we find acceptable. You still have overload protection, you still have earth fault protection with the rcd, you may have a mcb in the neutral. Personally I fitted an isolation transformer and I don’t care what polarity comes out of the socket in the marina - that's was the result of my risk assessment for our metal boat!

Where did you get the idea I was criticising European engineers? I didn't mention what country I was referring to, you are just as likely to have polarity problems in the UK!
Regulations, standards and expectations change and what we use on boats has changed, I was working on an American Legend with the mains 230v and12v systems in the same panel no separation, you could easily put the 12v wire in a 230v terminal, that was how legend built there boats then hopefully not now. Many of the 12v and 230v systems on older boats are not what we would expect now, the same with houses. I would expect a new boat electronics from any manufacturer to be double pole mcb's now as caravans have been for many years. I would still like the correct polarity.

Hi Paul,

No need for apologies as I was not offended by your post, merely pointing out, as a chartered electrical engineer, my view on the issue and the safe convenient way of dealing with it for those who visit the continent with their boats. I agree, as you say, that it's a matter if assessing the risk and proceeding in accordance with your appetite for risk, but personally I have little appetite for a potentially fatal risk that can be averted by 2 minutes at the most of plugging in and testing.

Sorry you took my comment on a common British perception as aimed at you, that was not my intention and is the reason why that is a separate paragraph and clearly stated that many Brits have that perception. I disagree that neutral / live crossovers (I dislike the use of the word polarity with respect to AC, where polarity reverses 100 times per second) are just as likely in the UK, as British electricians are brought up with single pole protection being common, which makes such a crossover potentially dangerous and so take greater care to avoid crossovers. I certainly would not tolerate a crossover on any supply in the substantial marina I serve as a director of, any pillar found to have that issue would be isolated immediately until it was rectified. We have a duty of care to all our customers. I very much doubt any other UK marina would act any differently.

Peter.

 

[PeterWright]

Thanks. Just checked and i have double pole RCD and CB so very pleased.
View attachment 148257

www.solocoastalsailing.co.uk

Hi Plum,

Unsurprising to see that a French built boat is fitted with French made electrical protection, of continental european dual pole standards. In your case, as you have read earlier in the thread, there is no real need to fit a crossover adapter should you find that the supply is crossed over. Please re assess this position if you ever change boats.

Peter.

 

[westernman]

the wiring regulations don’t apply to boats

RCD (as in Recreational Craft Directive) includes required standards for wiring including double pole RCDs (as in Residual Current Device).

 

[dankilb]

[Deleted quoted content removed]

You've surely been on here long enough (2006) to witness this happen on multiple occasions? Someone new or who posts infrequently comes along, adopting a strong position that contradicts the conventions in the industry, then gets in a huff when our resident experts stand their ground.

Thankfully the resident expert(s) - Paul in this case - have thicker skin and stick around after the various opinionated posters have long-since sloped off. We all benefit hugely from advice from someone like Paul, whose knowledge reflects exactly how things are done in our industry (in the UK) and for which we'd otherwise have to pay. That's not to say that discussion of how things are done in houses or caravans isn't also useful. I've found this insightful and learned from it. But we benefit more from (marine) industry-standard advice at the click of a button, than we do from musings on how things might or ought to be based on other industries, applications or, yes, even (domestic) regulations.