Electric sockets - completely lost

[RickS]

As some of you may know I have taken on a boat without knowing much about them, and rely quite heavily on this forum for help.

 

My present concern is electrical - the boat has square pin sockets (like normal domestic ones) throughout - some are labelled 12V but I don't know how reliable that is.

At the moment I am on shore power so fairly easy to find which sockets work. my problem is that when I come to run stuff from the inverter, are all the sockets going to run 230V ?

Ideally I would like to have 12V sockets (car lighter sockets?) to be able to run / charge USB devices. My thoughts on testing is to take a 230v device and plug it in (when running from an inverter) to see if the socket supplies 230V or !2V - I know some of you will be raising eyebrows at this.

If they are all running 230V from the inverter, how do I get said 12V sockets? Run a supply from the RCD? 

Also, I try to follow posts on here about batteries and charging but really confusing - anyone recommend a basic book etc about charging battery banks oplease?

Thanks as always

[David Mack]

It's a REALLY bad idea to have the same type of socket used for 12V dc and 230V ac. Sooner or later you or someone else is bound to plug something into the wrong socket and things may go bang (or worse).

 

I would hope at least that the 12V sockets are wired so that the negative uses the earth pin and positive uses the neutral pin, which will minimise the chances of damage or injury.

 

If you only need 12V sockets to charge USB appliances, why not just fit 5V USB sockets and avoid using separate 12V to USB converters. There's a couple of recent threads about it on here.

[Higgs]

 

Can't imagine why you'd choose to put similar sockets in for the two different supplies, unless one is inverter supply and one mains shoreline. But still, a bad idea. 

 

 

Edited December 29, 2020 by Higgs

[TheBiscuits]

 

I agree with David - I really hope the ones labelled 12V are in no way possibly connected to the 240V, but there are no guarantees if a previous owner decided using standard sockets for both was a good idea!

 

A quick check would be to look at the cable going into the sockets.  Hopefully they at least used different cable to wire them in - if you have all the labelled 12V ones taking a red and black cable only and the working 240V ones having either red/black/green+yellow or blue/brown/green+yellow then it's possible they are wired correctly.

 

 

[David Mack]

3 minutes ago, TheBiscuits said:

if you have all the labelled 12V ones taking a red and black cable only and the working 240V ones having either red/black/green+yellow or blue/brown/green+yellow then it's possible they are wired correctly.

But I think I'd want to check every one with a multimeter just to be sure. Measure the voltage between all three pairs of pins (I.e. L-N, L-E, N-E) first with the meter set on a 230V ac range, and the if that shows nothing on a 12V dc range. Don't try to measure mains voltages on a low voltage dc range as your meter may well start emitting magic smoke.

[TheBiscuits]

2 minutes ago, David Mack said:

But I think I'd want to check every one with a multimeter just to be sure. Measure the voltage between all three pairs of pins (I.e. L-N, L-E, N-E) first with the meter set on a 230V ac range, and the if that shows nothing on a 12V dc range. Don't try to measure mains voltages on a low voltage dc range as your meter may well start emitting magic smoke.

 

Good advice, but I think I'd advise he does it with shorepower disconnected, inverter off and test at 12V.

 

If all the ones labelled 12V are live at 12-13V and all the unlabelled ones are dead then it should be safe to say they are on different circuits.

 

@Rick Savery has said he doesn't know a lot about electrics, so careful testing with a multimeter might not be his forte.  Using a mains tester plug as he asked about isn't a bad idea - it will at least indicate which are live 240V and which are not.

 

29 minutes ago, Rick Savery said:

Also, I try to follow posts on here about batteries and charging but really confusing - anyone recommend a basic book etc about charging battery banks oplease?

 

Have you looked at @WotEver's pinned thread?

 

 

[TheBiscuits]

 

For clarity, by mains tester plug I mean something like this:

 

 

There are many different ones available, and they are much safer than plugging a kettle into a 12V socket ...

[tehmarks]

A mains testing plug is a good idea if you don't feel confident with a multimeter, but the meter will give you more information (and you'll learn a useful new skill in the process). Just follow the golden rule and don't touch the shiny bits! Also as mentioned above, if you do as mentioned above and test with the 230V (unambiguously) isolated, the danger is nonexistent. Though for completeness, I'd also want to meter the 230V circuits too.

 

The pin-out for a UK 230V socket, as designed and as you look at it, should be:

    PE

N       L

 

But I'd meter between all combinations of pins. For mains, you should have 230V between both L and N, and L and PE. You should have 0V between N and PE

 

Once you've established what's what, change the LV socket type as a matter of urgency. Using the same connector for both will lead to magic smoke escaping from something, eventually.

 

7 minutes ago, TheBiscuits said:

There are many different ones available, and they are much safer than plugging a kettle into a 12V socket ...

If you plug a kettle into a 12V socket, very little will happen.

[PD1964]

49 minutes ago, Higgs said:

 

Can't imagine why you'd choose to put similar sockets in for the two different supplies, unless one is inverter supply and one mains shoreline. But still, a bad idea. 

 

 

An inverter is designed to produce 240v also, I’ve never seen a boat with two 240v ring systems for inverter and shore. As you say a bad and confusing idea.

  Some boats still use the old style round 3 pin 12v sockets to supply 12v appliances with the round pinned plugs and if you have not seen these before they could confuse you into thinking they are a specialist 240v boat thing if not labelled 12v only.
 

Edited December 29, 2020 by PD1964

[ditchcrawler]

The sockets will NOT change from 240 ac to 12 dc volts, not possible. It is possible that some may not be live when on shore power, like one for a battery charger, immersion heater, washing machine to prevent them accidently powering these items from the invertor.

[RickS]

Thank you everyone who has answered. Still slightly confused  - I am reasonably OK with using a multimeter (he says!), rather than shoving the needles from the multimeter into the holes would I be better off doing that to the back of the sockets, if you see what I mean.

Also, I think - or rather assume- that those sockets that are labelled 12v are those connected to the inverter, so effectively will run at 240V when running. It is very confusing and I don't see that it is logical or sensible to use the same sokcets for both shore mains and inverter mains - what if the labels fell off? Bonkers

So a tester plug (as mentioned by TheBiscuits) would work on those labelled 12V when the inverter is on?

I can't see how or why they would supply 12V yet use the same socket as 240V as I thought 12V devices aren't plugged up that way.

I agree with running 5V supplies for USB but unsure how I would do this - would it be a completely separate installation or could the existing wiring be used but just disconnected from going through the inverter.

Also (this really shows how little I know) I assume that when running without shore mains, those sockets would just not work, rather than also being utilised by the inverter (no idea how that would work, or even if that makes any sense, sorry!) 

Just so I'm clear - is it possible that some of the square-pin sockets(labelled 12V) may, in fact, be running 12V dc rather than my assumption that they would all be running 240Vac via the inverter?

 

If so, really confused by why that would be done

[PD1964]

Are you still in the Marina?? I think you need someone with experience with boats and there systems just to walk you around and explain the 12v and 240v system layout and the differences with being on shore power and Inverter, before you confuse yourself too much.

  Looking at the pictures you posted when you bought it, it looks like there shouldn’t be anything out of the ordinary with the set up. Then again? Good luck.

Did you get the boat surveyed before purchase? 

Edited December 29, 2020 by PD1964

[Higgs]

31 minutes ago, PD1964 said:

An inverter is designed to produce 240v also, I’ve never seen a boat with two 240v ring systems for inverter and shore. As you say a bad and confusing idea.

  Some boats still use the old style round 3 pin 12v sockets to supply 12v appliances with the round pinned plugs and if you have not seen these before they could confuse you into thinking they are a specialist 240v boat thing if not labelled 12v only.
 

 

My boat still has a few of the unmistakable smaller plugs for the 12v DC circuit. These are far too small to be confused with standard domestic 240v AC sockets. 

 

 

Edited December 29, 2020 by Higgs

[Murflynn]

15 minutes ago, Rick Savery said:

Thank you everyone who has answered. Still slightly confused  - I am reasonably OK with using a multimeter (he says!), rather than shoving the needles from the multimeter into the holes would I be better off doing that to the back of the sockets, if you see what I mean.

Also, I think - or rather assume- that those sockets that are labelled 12v are those connected to the inverter, so effectively will run at 240V when running NOT. It is very confusing and I don't see that it is logical or sensible to use the same sokcets for both shore mains and inverter mains - what if the labels fell off? Bonkers

So a tester plug (as mentioned by TheBiscuits) would work on those labelled 12V when the inverter is on?

I can't see how or why they would supply 12V yet use the same socket as 240V as I thought 12V devices aren't plugged up that way.

I agree with running 5V supplies for USB but unsure how I would do this - would it be a completely separate installation or could the existing wiring be used but just disconnected from going through the inverter.

Also (this really shows how little I know) I assume that when running without shore mains, those sockets would just not work, rather than also being utilised by the inverter (no idea how that would work, or even if that makes any sense, sorry!) 

you are making this incredibly complicated.

 

your sockets are either on a 230v loop or a 12v loop,  They can't be on both.

 

the inverter will not change the voltage at the socket. 

 

as explained earlier:

 

-  with no mains power or inverter power, test each socket with a multimeter set at 12v DC, testing between each pair of socket holes.  Mark the sockets that have (about) 12v and identify the working pair (checking for +ve and -ve.

 

-  now with shore hook-up test the remainder of the sockets with a table lamp or summat like that.  Mark the sockets that are live on mains hook-up.

 

-  If some sockets are neither 12v or 230v mains, power up the inverter and test again for 230v, marking any sockets that only provide 230v when the inverter is on.

 

-  if there are sockets that never had power then check wiring, fuses, etc.

 

 

 

Edited December 29, 2020 by Murflynn

[Alan de Enfield]

23 minutes ago, Rick Savery said:

Just so I'm clear - is it possible that some of the square-pin sockets(labelled 12V) may, in fact, be running 12V dc rather than my assumption that they would all be running 240Vac via the inverter?

It SHOULD mean that the ones labelled 12v are connected to the batteries and provide 12v for things that require 12v DC

 

The ones NOT marked 12v SHOULD be supplying 230v AC from either the shoreline OR the inverter (the inverter INPUT is 12v DC and its OUTPUT is 230v AC)

You may have a switch over to select 'Inverter' or 'shoreline'.

Edited December 29, 2020 by Alan de Enfield

[Higgs]

3 minutes ago, Alan de Enfield said:

It SHOULD mean that the ones labelled 12v are connected to the batteries and provide 12v for things that require 12v DC

 

The ones NOT marked 12v SHOULD be supplying 230v DC from either the shoreline OR the inverter (the inverter INPUT is 12v DC and its OUTPUT is 230v AC)

You may have a switch over to select 'Inverter' or 'shoreline'.

 

Is that unintentional?

 

 

[Alan de Enfield]

4 minutes ago, Higgs said:

 

Is that unintentional?

 

 

 

Yes it is an error - it should say 230v AC

 

Edited December 29, 2020 by Alan de Enfield

[PD1964]

On your 12v control panel is there a switch for “12v Sockets” or anything that can help identifying a 12v ring system and is it wired up, this may give you some help.

  As stated above not recommended to use standard 240v sockets and plugs for 12v system, should be smaller round pin 12v hardware.

 

[PaulD]

The sockets marked 12v could be connected to either 12v or the 230v from the inverter. As there seem to be no wiring diagrams to clarify this is potentially dangerous.

The OP should use the multimeter to find out and if any are 12v the sockets should be changed to a clearly different type.

 

Not sure the OP is safe doing this.

[Guest]

8 minutes ago, PaulD said:

The sockets marked 12v could be connected to either 12v or the 230v from the inverter. As there seem to be no wiring diagrams to clarify this is potentially dangerous.

The OP should use the multimeter to find out and if any are 12v the sockets should be changed to a clearly different type.

 

Not sure the OP is safe doing this.

I'm wondering if the boat has somehow been wired so that the ones marked 12V provided 240 V AC but from the inverter only.

 

And the ones that are 240 V are purely direct from the shore line.

 

Personally I would get it checked by somebody suitably qualified and competent.

[Slim]

1 hour ago, PD1964 said:

inverter is designed to produce 240v also, I’ve never seen a boat with two 240v ring systems for inverter and shore. As you say a bad and confusing idea.

I, quite correctly, have two 230v circuits on my boat. One circuit is fed by either the shorepower or generator and supplies heavy demand appliances such as the washing machine, dryer and 2 Kwh immersion heater whilst the other circuit supplies only low demand appliances such as TV, microwave, fridge etc. Everything is fed through a 100/2000 Mastervolt combi totally in accordance with MV instructions. All the manuals are on the boat so can't quote precise details off hand.

 

I'm keeping out of the main question as I'm uncomfortable about the OPs level of technical understanding.

Edited December 29, 2020 by Slim

[Higgs]

12 minutes ago, PaulD said:

The sockets marked 12v could be connected to either 12v or the 230v from the inverter. As there seem to be no wiring diagrams to clarify this is potentially dangerous.

The OP should use the multimeter to find out and if any are 12v the sockets should be changed to a clearly different type.

 

Not sure the OP is safe doing this.

 

If there is an alternative 240v AC supply via the inverter, it is hoped it doesn't bypass the main box and circuit breakers. 

 

 

 

 

[tehmarks]

1 hour ago, Rick Savery said:

Thank you everyone who has answered. Still slightly confused  - I am reasonably OK with using a multimeter (he says!), rather than shoving the needles from the multimeter into the holes would I be better off doing that to the back of the sockets, if you see what I mean.

I would personally do it through the front of the socket rather than unscrewing it from the wall, but thanks to a clever safety feature of British sockets, the bottom (live and neutral) holes are shuttered unless something (usually the pin of a plug) is inserted in the top (earth) hole. I personally think that's safer than the faff of unscrewing the frontplate from the wall and trying to probe terminals which are now just flapping around on the end of a cable in an awkward place — but obviously I can't condone sticking things other than plugs in mains sockets...

 

If you did decide to go down that route, even though the top terminal should be at earth potential ('dead'), I'd probably use something non-conductive in case you have a defective installation.

 

Quote

I can't see how or why they would supply 12V yet use the same socket as 240V as I thought 12V devices aren't plugged up that way.

If a clueless moron owner has done their own installation, they could be plugged up any way! I wouldn't assume anything, because one way or another the installation is non-standard.

Quote

Also (this really shows how little I know) I assume that when running without shore mains, those sockets would just not work, rather than also being utilised by the inverter (no idea how that would work, or even if that makes any sense, sorry!) 

1. With the 230V isolated, make sure all the 12V circuits are connected (ie breakers not tripped, etc) and meter the sockets labelled 12V. If 12V, stop here. If 230V:
2. Switch the inverter on and meter everything carefully.
3. Switch the inverter off, switch the shore power on and meter everything carefully.

If you get 12V out of a standard mains socket, these need swapping or decommissioning urgently. The sockets themselves aren't dangerous as plugging a 230V appliance into a 12V supply will just safely fail to work. But if you have any 12V appliances with equivalent plugs on them, cut them off immediately and replace with a more suitable connector.

 

The latter two steps will help you determine if someone has installed separate circuits powered by shore power and the inverter — which is weird, but not dangerous. If power comes out of everything on both shore power and inverter, and you haven't switched a changeover switch, and the inverter doesn't have a changeover feature, then you possibly have a dangerous installation with the shore power and inverter commoned.

Quote

Just so I'm clear - is it possible that some of the square-pin sockets(labelled 12V) may, in fact, be running 12V dc rather than my assumption that they would all be running 240Vac via the inverter?

It'd be moronic, but it's very possible.

Edited December 29, 2020 by tehmarks
Emphasis added to take care!

[Guest]

21 minutes ago, Slim said:

I, quite correctly, have two 230v circuits on my boat. One circuit is fed by either the shorepower or generator and supplies heavy demand appliances such as the washing machine, dryer and 2 Kwh immersion heater whilst the other circuit supplies only low demand appliances such as TV, microwave, fridge etc. Everything is fed through a 100/2000 Mastervolt combi totally in accordance with MV instructions. All the manuals are on the boat so can't quote precise details off hand.

 

I'm keeping out of the main question as I'm uncomfortable about the OPs level of technical understanding.

I suspect this is how the OP's boat has been wired BUT in the absence of seeing a diagram it's not possible to say.

 

I also wonder why if it as been so wired why each socket isn't labeled 'Inverter' and 'Shore/genny' or some such to differentiate.

 

I still urge the OP to get somebody competent to have a proper look rather than try and get forum members to second guess and advise over the internet. Feels like a recipe for disaster to me.

[MoominPapa]

There is a way to use the same type of sockets for 12v and 240v and make confusion between the two impossible. Note that I don't recommend doing this, but I have seen it done.

 

The trick is to remove the earth pin from the plugs to be used for 12v and install it permanently in the socket connected to 12v. That means 12v plugs without an earth pin cannot be plugged into 240v sockets as there's nothing to operate the shutters. Similarly 240v plugs with an earth pin won't go into 12v sockets because the earth pin hole is blocked. 12v sockets don't get shutters and earth connections, but they are safe without either.

 

Nasty, but effective.

 

MP.