Reversing neutral/active automatically

[Grandad]

Ok, first of all, in line with Bruce's Admin Notice at the start of this sub-forum I offer the following.

1. I am not now nor ever have been a licensed electrician.
2. I have tried to find a sparky here in Bendigo who is conversant with AS/NZS 3001. So far, I have received the following advice from licensed electricians in my area who claimed to know all about these standards.
a) No worries mate. Wiring a caravan is no different to a house.
b) Don't worry about double poled switches. Who told you you needed those? You read it on the internet???? Normal ones will be fine
c) An RVD? What the hell is that? You don't need it. A regular safety switch will be fine.

(BTW. I've been in touch with Ian from RVD Safe and he knows no-one in the Bendigo area but assures me his supplied PDF file is enough for any electrician to install one.)

d) Yah, it's only a caravan. I'll send my apprentice out. Just tell him what you want.
Plus, many, many, many more.

I WILL get an elecrician to do the job. Well, fit it off anyway. The cabling had to be run when I was reconstructing the walls. I'll attach a photo.

IMG_0413 (Small).JPG

I've worked with this man before. He admits to not knowing AS/NZS 3001 but I trust him, and he knows me and that I'm not an idiot. Between the two of us. We'll work it out. It won't be the first time we've worked out a problem together.

So, I would VERY much appreciate not being told, "Talk to a licensed electricial contractor". Been there, done that. Multiple times!

Ok, on to my question. It's complicated, and expensive to find and fit doubled poled everything in my Vintage van. Being built in 1969, it didn't originally have doubled poled anything.

It got me thinking. The reason for doubled poled switches is because it can be plugged in anywhere. Is the power point being used wired correctly? As I have seen personally, many have the active/neutral reversed.
So, to be safe, let's switch both. Fair enough.

When I was a wee tacker, travelling with my parents in Canada in Dad's Airstream, nothing was doubled poled either. The electrical plugs in the 60's in Canada were two parallel prongs with no earth pin. It was a 50/50 chance when you plugged the caravan into 110V power whether you got it the right way around.
So, to get around this little problem, Airstream had a little red light inside. If you put the plug in the wrong way around, this little red light would light up. I still remember hearing my Dad. "Margaret? Is the light on?"

I went looking for how this was done and found this.

polarity warning.jpg

Now, immediately, I notice the light is between active and ground??? Really? Would that work? On DC? Sure. On AC? Really? That's question 1.

Question 2. If this wouldn't work, what would?

Ok, assuming I can get a satisfactory answer to that one, what would happen if instead of powering a light to tell me the active/neutral is reversed, what if we used it to power a DPDT relay that instead of warning me there was a problem just solved it by reversing everything?
Like this?

Relay.jpg

Now, at the end of the day, ALL of this work is above my pay grade. If you guys tell me my idea is feasible, I will talk to the sparky I spoke of. In 12VDC, I'd be all over this. In 240VAC? Nup. Too much can go wrong. So, I'm after practical advice on how? NOT....Just talk to an electrician.

Does this cover your terms of use ok Bruce? Tell me if it doesn't. I don't want anybody getting into trouble.

Over to you guys and thank you in advance.

Cheers
Jim

[Newcastle George]

I purchased a tester which I leave plugged into one of the MH power points. It has warned me of incorrect connections at a number of caravan park power points

George

[BruceS]

Yep, all good!
Pretty well anything is OK here unlike some other forums.
You really do think along similar lines to me in regards to double pole switching and RVD's.
Look I know all these things ARE good & probably an improvement over 1960's technology but let's face it .... most of us survived didn't we?
It's a bit like "never cross a railway line & you'll never get hit by a train" isn't it?
There are simple gadgets to check wiring & to be honest I've used it after an electrician did work for me!!!
https://www.ebay.com.au/itm/NESCO-Power ... ctupt=true
A lot of these updated requirements apply to factories building new vans but I doubt it'd apply to a renovation!

[supersparky]

Jim, I am a licenced electrician. Please don't fit a polarity reversing switch into your caravan. Apart from anything else it is illegal.
The reason is that if polarity is reversed it only requires one fault to occur and these chassis and frame of your van could be at 240v potential. Like Bruce said, we all lived so far but why take the chance.
The licencing authorities don't make up those rules for no reason.
The simplest way to check for reversed polarity is to purchase a RCD/Polarity tester. Bunnings have them. Any electrical wholesaler will also sell them.Lots of different types on ebay. https://www.ebay.com.au/p/Cabac-TEL1TLV ... 753&chn=ps
If you only use 12 0r 24v dc for your lighting then you would only need a few 240v GPO's fitted. The double pole ones aren't that much more expensive. There are people on these pages that will also say that you don't need this or that, but if you get an RVD fitted and tested then you know that you won't be responsible for someone having an electrical accident.

[Grandad]

George and Bruce. My first thought for the warning light was in fact one of those testers. But I was planning on reverse engineering one so it could be built in all neat like. Take everything out of the case and rearrange things to my liking. Like, put the light outside where the power plugs in.

But when I found the schematic for one, that peaked an idea.
I may still end up doing that. Then my question would be, how much voltage/amperage is needed to throw the electromagnet in a relay?
I can probably experiment and find that out.

So, Bruce, "Pretty well anything is OK here unlike some other forums." Does that mean I won't hear any 'SHALL's' or 'SHALL NOT's'
Or am I just being cheeky now?

I'd really like to see if I can figure this out if for no other reason than to see the look on my sparky's face when I show him. I can hear him now. "What the hell have you got me into this time?"

Jim

[Grandad]

Thanks David, you posted while I was replying.
I'm confused. You said, "The reason is that if polarity is reversed it only requires one fault to occur and these chassis and frame of your van could be at 240v potential"
Yes, that would be the case if the polarity is reversed. What I am trying to do is CORRECT this so a reversed polarity situation is corrected. Where is the danger in that?
Jim

ETA. Also, testing is fine. You check, and the wires are reversed. Now what? The idea of testing is to find a fault. Logically once a fault is found, it has to be corrected. If you look at my schematic, if the neutral/active are correct, the relay is dead. No change. I'm only reversing things if they're wrong to start with.

[supersparky]

Jim, I have sent you a PM.

[BruceS]

Well, Well, Well!!!
To be honest I hadn't read a lot of these posts on the first thread in this section since I was advised to just let the conversation flow with very little interference.
I just read all of the posts.
There will never be any quoting "shall" or "should" on this forum while I'm Admin.
I deliberately wanted this forum to be an OPEN forum for discussion.
I want to post something HERE but I'll need to go 'grab' it & post it word for word in a minute ....
OK, I read this for the first time!
oldtrack123
Wed Jan 02, 2013 6:35 pm
Hi All
OK
Are we ALL prepared to State
"I will not make comments on subjects that I am not currently QUALIFIED for by a piece of paper
"or
"I will only comment on topics for which I have a CURRENT qualification /license""

PeterQ
DEFINITELY NOT!!!
Any & all comments are most welcome on this forum & in this section.
A comment is not an instruction & in fact an instruction still does not say that the instruction will be carried out ... does it?
How dare someone try to instruct others how to engage in free speech!
Bruce (Admin)

[jon_d]

If the caravan park is wired correctly then why is it needed?

The change over switch has better be a good quality break before make.... good luck if it's not!

[supersparky]

If the caravan park is wired correctly then why is it needed?

The change over switch has better be a good quality break before make.... good luck if it's not!

Jon, What happens, and I reckon that we have all probably done it, is that when we replace the plug on the end of the lead, usually cos we drove away with it still plugged in.
It is so easy to cross over the wires and have a permanent reverse polarity connected lead.
Hands up if you are the one person that has never driven off and left something plugged in or left hanging out?