How do you wire yours?

[twocvbloke]

Something I've been wondering, I remember something a while back where someone mentioned a technique to wire up round-pin BS546 sockets so they were "safe" incase you used the 12v item in a 240v wired socket and vice versa...

 

So, it got me wondering, how do you wire yours up for 12 Volt use? I remember something being mentioned that the Earth pin is used as either positive or negative (but forgot which one it was)...

 

I'm not planning any 12v wiring, I just happened to think about it cos I bought these sockets:

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=220728808057

[David Schweizer]

Something I've been wondering, I remember something a while back where someone mentioned a technique to wire up round-pin BS546 sockets so they were "safe" incase you used the 12v item in a 240v wired socket and vice versa...

 

So, it got me wondering, how do you wire yours up for 12 Volt use? I remember something being mentioned that the Earth pin is used as either positive or negative (but forgot which one it was)...

 

I'm not planning any 12v wiring, I just happened to think about it cos I bought these sockets:

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=220728808057

The safest proceedure is to always use a square pin 13amp plug for mains equipment, and a 5amp round pin on all 12v DC equipment. That way there can be no mistakes.

 

We use 5amp round pins sockets and plugs on our boat for 12v DC equipment. I wire the positive to the live teminal and the negative to the neutral terminal. I belive this is the standard convention.

Edited January 31, 2011 by David Schweizer

[Doorman]

The safest proceedure is to always use a square pin 13amp plug for mains equipment, and a 5amp round pin on all 12v DC equipment. That way there can be no mistakes.

 

We use 5amp round pins sockets and plugs on our boat for 12v DC equipment. I wire the positive to the live teminal and the negative to the neutral terminal. I belive this is the standard convention.

 

Ditto...!

 

Edited to add...... any round pin sockets to be labelled up as 12v only!

Edited January 31, 2011 by Doorman

[twocvbloke]

The safest proceedure is to always use a square pin 13amp plug for mains equipment, and a 5amp round pin on all 12v DC equipment. That way there can be no mistakes.

 

We use 5amp round pins sockets and plugs on our boat for 12v DC equipment. I wire the positive to the live teminal and the negative to the neutral terminal. I belive this is the standard convention.

 

That's the thing, to someone like myself, who likes vintage appliances that still have 5A plugs fitted, there could still be some confusion of the standards, I know it's unlikely that someone would have a vintage appliance collection on a boat, but you never know. 12v into a 240v device could be a hazard, but 240v into a 12v device is just an accident waiting to happen...

 

Like I say, I'm sure I read on here that someone used the earth terminal for one of the supply lines, thus reducing the risk of any cross-contamination of the voltages, I think I'll go search through my posts for that now...

 

Personally I'd still want to use the US style 12v sockets (as used in caravans, but they're just basically US plugs and sockets), but that's just my personal preference...

[alan_fincher]

The safest proceedure is to always use a square pin 13amp plug for mains equipment, and a 5amp round pin on all 12v DC equipment. That way there can be no mistakes.

 

We use 5amp round pins sockets and plugs on our boat for 12v DC equipment. I wire the positive to the live teminal and the negative to the neutral terminal. I belive this is the standard convention.

I do the same as David, but am well aware that some people, (like I think Allan Jones), prefer to not use the live pin.

 

I think it was Allan who said he uses Earth for Negative, (because negative will be earthed to the boat), but then the Neutral for the 12 volts positive.

 

Whilst I understand the logic, connecting the positive to "Neutral" seems highly unintuitive to me.

 

I have no plans to take my 12 volt equipment off the boat to places where it might get connected to 240 volts, so don't see an issue with using "Live" for positive.

 

Clearly there is no universally accepted way of doing it though.

[twocvbloke]

Clearly there is no universally accepted way of doing it though.

 

Which could be problematic, like if you move from one boat to another, only to find your 12v kit isn't working or has blown up cos someone chose a different method of wiring up their 12v sockets or plugs...

 

Standardisation would be a good thing...

[Keeping Up]

Unfortunately if a standard were to be introduced,it would almost certainly not include the use of these excellent plugs.

 

On my own boat I have those cigarette-lighter plugs which are notoriously unreliable, but (as Alan says) if I were using 3-pin round pin plugs for 12v I would definitely use the neutral and earth pins and leave the live pin unused. In that way if the equipment should ever happen to be plugged into a round-pin socket carrying 240v there would be no fireworks and no deaths.

 

As to the polarity, again as Alan says I prefer to put the negative on the "earth" pin, so that if any equipment (or the socket itself) has a metal chassis connected to the earth pin there will be no sparks if it touches any other metalwork (or earthed 240v equipment) but I accept that I am probably in the minority there.

 

Edited for clarity after being poorly expressed originally

Edited January 31, 2011 by Keeping Up

[alan_fincher]

As to the polarity, again as Alan says I prefer to put the negative on the "earth" pin, so that if the equipment has a metal chassis there will be no sparks if it touches any other metalwork (or earthed 240v equipment) but I accept that I am probably in the minority there.

Now there you have me confused, Allan.

 

Why should it matter what pin(s) you use to pass the 12 volts through the 5 amp socket and plug, as to the "state of earthedness" of your 12 volt equipment.

 

I reckon anything I have that had 12 volts negative connected to its casing would be just as safe if it touched the metalwork of the boat, or any earthed 240 volt equipment, as yours would.

 

Why does whether my negative is wired through the "fat pin" or a "thin pin" make any difference ?

 

Or have I misunderstood completely ?

[Gibbo]

Now there you have me confused, Allan.

 

Why should it matter what pin(s) you use to pass the 12 volts through the 5 amp socket and plug, as to the "state of earthedness" of your 12 volt equipment.

 

If a piece of 230 volt equipment (with one of those old plugs on it) is plugged into the 12 volt system, and positive is on the earth pin (like many people would do it) then the case of the 230 volt equipment has 12 volts on it. If it touches something else that is earthed you've got a popped fuse and some sparks.

 

 

As to the polarity, again as Alan says I prefer to put the negative on the "earth" pin, so that if the equipment has a metal chassis there will be no sparks if it touches any other metalwork (or earthed 240v equipment) but I accept that I am probably in the minority there

 

That's only because you've thought it through properly and the majority wouldn't have done

[Keeping Up]

Now there you have me confused, Allan.

 

Why should it matter what pin(s) you use to pass the 12 volts through the 5 amp socket and plug, as to the "state of earthedness" of your 12 volt equipment.

 

I reckon anything I have that had 12 volts negative connected to its casing would be just as safe if it touched the metalwork of the boat, or any earthed 240 volt equipment, as yours would.

 

Why does whether my negative is wired through the "fat pin" or a "thin pin" make any difference ?

 

Or have I misunderstood completely ?

 

No you're absolutely right, I blame my post (which I'll edit to avoid confusion) on it being a Monday morning. I don't do Monday mornings very well, especially since I retired. Upon reflection, the original reason I did it that way around was because it was on someone else's boat where they had used brass sockets whose earth pin was internally bonded to the face plate. They had also got brass square-pin 13-Amp sockets right next to them for the 240v supply, and they had called me in to investigate why they kept blowing the 12v trip; whenever the two faceplates touched (or were momentarily bridged as they tried to plug something in) there was a 12v short.

[alan_fincher]

OK,

 

All my sockets are plastic faced, and in plastic boxes, so a non-issue for us.

 

Just managed to type "suckets" there, before correcting it.... Good "word"......

[mayalld]

The safest proceedure is to always use a square pin 13amp plug for mains equipment, and a 5amp round pin on all 12v DC equipment. That way there can be no mistakes.

 

We use 5amp round pins sockets and plugs on our boat for 12v DC equipment. I wire the positive to the live teminal and the negative to the neutral terminal. I belive this is the standard convention.

 

Your confident assertion that "there can be no mistakes" ignores the fact that there can be mistakes.

 

What happens when somebody on board decides to take a piece of 12v equipment wired on round pin plugs, and plug it into a round pin socket elsewhere that is wired for 240v?

 

The risk-averse approach says that when presented with an unverified round pin socket, there is a risk that there may be 240vac on the lower right hand pin. In consequence (unless the appliance is capable of handling that 240v) you should not use that pin.

 

If the sockets are wired on earth and neutral, nothing bad is going to happen, EVEN if somebody plugs the wrong thing into the wrong socket.

[Gibbo]

No you're absolutely right...

 

I think you need to read post #9

 

You were right the first time.

[Keeping Up]

I think you need to read post #9

 

You were right the first time.

 

So I was. How unusual for a Monday morning..

 

Although as I said, upon recollection the initial reason was to do with a live brass faceplate rather than a piece of 240v kit; the other reasons came later.

[alan_fincher]

What happens when somebody on board decides to take a piece of 12v equipment wired on round pin plugs, and plug it into a round pin socket elsewhere that is wired for 240v?

That's the bottom line, isn't it?

 

I can't imagine any reason in the world why someone would take any 12 volt equipment from the boat elsewhere, and even less reason why they should possibly want to plug it in in any of the rare places you might still find these things being used for 240 volts.

 

For that reason I see no reason in the world to change mine.

 

Out of interest would you do the same as Allan - i.e. use the earth pin for negative, and neutral for positive ? I ask, because if I had thought of a scheme to avoid using the live pin, (which clearly I wasn't clever enough to!), I think I would have gone for negative on "neutral" still, and simply used "earth" for positive instead of "live" for positive.

 

In which case, if I took some piece of equipment where polarity mattered from one boat to another, (surely a more likely scenario than taking it to a 240 volt mains 5A socket ?), then it's not going to come to a heap of good, is it, (unless it has reverse polarity protective circuitry).

 

I wonder what most caravanners do, when they use these things for 12 volts ??

[Guest]

I wonder what most caravanners do, when they use these things for 12 volts ??

 

Well FWIW just used to wire pos to pos neg to neg. - suspect singly we are not a representative survey though.

 

The mains sockets in the 'van were std. square pin 240 volts so there was no confusion there and we never took the 12v appliances to anywhere from memory that had mains sockets like that.

[Gibbo]

I can't imagine any reason in the world why someone would take any 12 volt equipment from the boat elsewhere, and even less reason why they should possibly want to plug it in in any of the rare places you might still find these things being used for 240 volts.

 

I think you overestimate the intelligence of some people.

 

I used to own electronics shops (a bit like Maplin). You would be amazed at how many times we were asked for certain leads that simply would never exist. My favourite request was for (not just on one occasion either)...

 

A "scart to 13amp plug"

 

I am not making this up.

 

Broken finger edit.

Edited January 31, 2011 by Gibbo

[alan_fincher]

I think you overestimate the intelligence of some people.

Oh, trust me, I don't.

 

I've worked in both consumer electronics and IT support, so know what people are capable of, (and even some engineers are capable of!...)

 

I do however know the intelligence levels of those using my boat, and the 12 volt equipment aboard.

 

I'm prepared to trust them not to take it elsewhere!

[Guest]

Broken finger edit.

 

do tell, we like tales of pain and suffering on here...

[twocvbloke]

I wonder what most caravanners do, when they use these things for 12 volts ??

 

I'd guess sensible ones would use completely incompatible plugs for any standard, such as the following examples:

 

US-style Polarised plug & socket

 

The bog standard "Caravan" plug & socket (can't find a pic of a matching socket):

 

Or of course there's that clip-in DIN socket or the good old 12v cigar lighter socket...

[mayalld]

That's the bottom line, isn't it?

 

I can't imagine any reason in the world why someone would take any 12 volt equipment from the boat elsewhere, and even less reason why they should possibly want to plug it in in any of the rare places you might still find these things being used for 240 volts.

 

For that reason I see no reason in the world to change mine.

 

OK, let me suggest a scenario...

 

You have a 12V table lamp, wired to a round plug. You tire of it, and discard it.

 

Somebody sees the discarded lamp, picks it up, and plugs it in at their pub.

[twocvbloke]

Somebody sees the discarded lamp, picks it up, and plugs it in at their pub.

 

Hopefully they'd follow the rules first and have it PAT tested to reveal the wiring...

[Keeping Up]

Hopefully they'd follow the rules first and have it PAT tested to reveal the wiring...

 

The test would show that there was not an earth fault - so that'd be OK wouldn't it?

[Guest]

Hopefully they'd follow the rules first and have it PAT tested to reveal the wiring...

 

The plug wouldn't fit the little PAT testing appliance so it's irrelevant...

Edited January 31, 2011 by MJG

[steelaway]

I'd guess sensible ones would use completely incompatible plugs for any standard, such as the following examples:

 

US-style Polarised plug & socket

 

The bog standard "Caravan" plug & socket (can't find a pic of a matching socket):

 

Or of course there's that clip-in DIN socket or the good old 12v cigar lighter socket...

 

 

 

 

Eggsacaly -

 

Change them all to the PROPER PLUG AND SOCKET!

Just like caravaners

 

Alex