12V and 220V lighting - on same circuit

[DeanS]

I want to install small spot lights on my new boat.

 

1. reading lights on each side of the main bed.

2. one for each kids cabin.

3. 2 on each side of the kitchen.

4. 2 in the saloon.

 

Most of the time, we'll be in a marina, and I want these to be 220V GU10 type bulbs (5Watt LED). I want to use this type of holder. (they come with bulbs, but will throw the bulbs away)

 

Each lamp will have an on/off switch.

 

I want to feed these lights, using one 20Amp cable. On 220V, they each draw about 0.3A, and all together, about 3Amps. The reason I want to use a 20Amp supply cable, is that I want these spot lights to be able to change over to 12V bulbs when I'm away from shorepower. The way I'm thinking of doing this, is to change the GU10 bulbs, to MR16 type 12V (10Watt) bulbs, using an adaptor (GU10 to MR16).

 

I'm hoping to be able to select either 220V supply or 12V supply to all the spotlights, using this rotary switch. In position 1, the supply to the bulbs will be from the 220V supply side. In position 2, the supply to the bulbs will be direct from the batteries.

 

So, to summarise, when I'm on shorepower (many months a year), I'll switch the rotary switch to 220V, and use 220V bulbs. When cruising, I'll switch the rotary to 12V and use 12V bulbs.

 

The supply sides will be completely isolated. The rotary has a middle (off) point, so there's no risk of having sparks between 12V and 220V contacts.

 

Yes I know that the 220V bulbs are smaller wattage than the 12V bulbs, and I could just use the invertor and have 220V bulbs all the time, but I dont want that. Invertors beep and switch off under 11.9V, meaning no lights unless you have 12V bulbs in...but I dont want to use 12V when on shorepower, else I'll have to keep charging batteries for no reason.

 

Would this supply voltage selection technique be "disallowed" for any justifiable reason.

[Robbo]

Very bad idea, just use 12volt lights and a 3 step charger so you can leave it on 24/7 when on shore power. It's better for the batteries and the 12v appliacnces will be using the charger as a source.

[dor]

Robbo's got it right. Surely if you are going to be on a shoreline for extended periods you will have a multi-stage charger? All your lighting can be 12V with the 230V keeping the batteries in good condition. And you shouldn't let your batteries get down to 11.9V or they won't last long. And switches designed for 230V are not considered a good idea on 12V. And if you use the same wiring for 12V & 230V, sooner or later someone will make a mistake...

[by'eck]

Very bad idea, just use 12volt lights and a 3 step charger so you can leave it on 24/7 when on shore power. It's better for the batteries and the 12v appliacnces will be using the charger as a source.

 

Agree absolutely - extremely bad idea - stick to 12 volts as Robbo suggests and don't even dream of mixing 240v AC with 12v DC.

[DeanS]

Very well

 

To be clear though...

 

1. What happens to 220V bulbs if you connect them to a 12V source?

2. What happens to 12V bulbs if you connect them to a 220V source ?

 

I have a charger I bought from Halfords...it's got a nice digital face ...but no idea if it's a 3-step. It has a green LED which lights up when it deems the batteries to be fully charged...at which stage...I'm not sure if it just switches off, or keeps feeding the system. It cost me £50 a year ago. What 3-step charger are you talking about exactly?

 

I dont like 12V lighting...horrible....would only have them as backup lighting........

[ditchcrawler]

 

Would this supply voltage selection technique be "disallowed" for any justifiable reason.

I don't think its "disallowed" very little is, but its a recipe for disaster, follow the other advice about good full time battery charging.

[RLWP]

I don't think its "disallowed" very little is, but its a recipe for disaster, follow the other advice about good full time battery charging.

 

It will make the BSS inspectors job interesting, although I feel 'I don't understand it, it looks dangerous, fail' seems the most likely outcome

 

I hate to say this Dean, but like your gas installation question, you are way out of your depth again

 

Richard

[bizzard]

Quite a popular practice 30 odd years ago, mains bulb sockets used for mains bulbs whilst on a landline, and swopping them for 12v bus bulbs which fitted mains sockets when off on a trip. I'm not aware of anyone getting electrocuted.

Edited August 1, 2012 by bizzard

[system 4-50]

The dodgy point in your grand plan is the rotary switch.

 

Change this for some means of switchover that requires tools and is locked and only you have the key.

Then you are effectively "rewiring" the system on each changeover. Slightly more tedious but much safer.

 

I agree with others that this is a scheme that one wouldn't recommend to the general public. But where tight control of an operation is available as in your case then compromises can be made. You would have to change it if selling, and I don't know the BSS take on it.

 

Battery charging is a quite separate concern & one I know nothing about.

 

AIMO

[DeanS]

It will make the BSS inspectors job interesting, although I feel 'I don't understand it, it looks dangerous, fail' seems the most likely outcome

 

I hate to say this Dean, but like your gas installation question, you are way out of your depth again

 

Richard

 

Hi Richard.

As usual, I'm thinking outside the box. I then bring it to the forum, for feedback, fully expecting the normal redicule. There is nothing wrong with this idea in principle. If I had to remove the rotary switch, and use 12V bulbs and hardwire it to the 12V fusebox, you would all say, thats great. If I had to use 220V bulbs, and hardwire it to the 16Amp trip box, you would all say, thats fine. So just because I choose to propose a switch that can convert it from one to the other, doesnt make it a stupid idea. Of course I know that a thread entitled...12V and 220V on the same circuit, will fill many with horror and an immediate response of " dont do that". I havent yet done it..I've simply "put it out there" to assess the feedback

 

I still think that if I removed the rotary switch and hardwired it into one or the other system, you would then all say, "thats fine"....I gather it is actually the idea of a rotary switch which changes the supply...which is causing a bit of fuss

[RLWP]

Quite a popular practice 30 odd years ago, mains bulb sockets used for mains bulbs whilst on a landline, and swopping them for 12v bus bulbs which fitted mains sockets when off on a trip. I'm not aware of anyone getting electrocuted.

 

Bet they blew a load of 12v bulbs though when they forgot to swap them

 

Richard

[DeanS]

The dodgy point in your grand plan is the rotary switch.

 

Change this for some means of switchover that requires tools and is locked and only you have the key.

Then you are effectively "rewiring" the system on each changeover. Slightly more tedious but much safer.

 

I agree with others that this is a scheme that one wouldn't recommend to the general public. But where tight control of an operation is available as in your case then compromises can be made. You would have to change it if selling, and I don't know the BSS take on it.

 

Battery charging is a quite separate concern & one I know nothing about.

 

AIMO

 

Thank you. Yup...the dodgy bit is the rotary switch

 

Looking at the actual risks of this..

 

1. If the 220V supply was fed to 12V bulbs...the moment you switched it on, it would pop I imagine?

2. If the 12V supply was fed to 220V bulbs...I guess they would just not light up.

 

Both of these options seem to be low risk.

[RLWP]

<snip>

which is causing a bit of fuss

 

Actually it was the unusual idea followed by 'I've got a £50 charger from Halfords - will that do' that revealed your level of knowledge to me

 

Have a look at a modern 12V/240V boat installation - I have. They are complex and sophisticated and are well planned. Not designed by forums

 

Richard

Edited August 1, 2012 by RLWP

[bizzard]

Hi Richard.

As usual, I'm thinking outside the box. I then bring it to the forum, for feedback, fully expecting the normal redicule. There is nothing wrong with this idea in principle. If I had to remove the rotary switch, and use 12V bulbs and hardwire it to the 12V fusebox, you would all say, thats great. If I had to use 220V bulbs, and hardwire it to the 16Amp trip box, you would all say, thats fine. So just because I choose to propose a switch that can convert it from one to the other, doesnt make it a stupid idea. Of course I know that a thread entitled...12V and 220V on the same circuit, will fill many with horror and an immediate response of " dont do that". I havent yet done it..I've simply "put it out there" to assess the feedback

 

I still think that if I removed the rotary switch and hardwired it into one or the other system, you would then all say, "thats fine"....I gather it is actually the idea of a rotary switch which changes the supply...which is causing a bit of fuss

I can't remember really but i think it was done with a rotary switch or more likely just two plugs of the same type,one mains and one 12v plugging and unplugging into the light circuits one. All very high tech stuff, probably way above the heads of electricians on here,ahem. (Reliable though, not much to go wrong).

 

And all probably wired up with that lovely old rubber and fabric covered twin twisted flex.

Edited August 1, 2012 by bizzard

[Gibbo]

You say you don't like 12 volt lighting. So why not just wire it up as all 230 volts and put a small inverter on it for when out cruising and a changeover switch to shorepower when in the marina?

[DeanS]

Actually it was the unusual idea followed by 'I've got a £50 charger from Halfords - will that do' that revealed your level of knowledge to me

 

Have a look at a modern 12V/240V boat installation - I have. They are complex and sophisticated and are well planned. Not designed by forums

 

Richard

 

I dont want a complex and sophisticated system. They're a nightmare when something breaks...and expensive to fix.

 

You say you don't like 12 volt lighting. So why not just wire it up as all 230 volts and put a small inverter on it for when out cruising and a changeover switch to shorepower when in the marina?

 

 

Yes I could do that...but there's still the slight chance that my kids XBox drains the batteries and the lights go off I have come to hate the sound of an invertor beeping...normally because we are running multiple laptops, tvs, etc, when we shouldnt be. Those 12V lights in my current boat, have always been a bit of a relief to have...

[Chris Pink]

 

1. If the 220V supply was fed to 12V bulbs...the moment you switched it on, it would pop I imagine?

 

 

I'm not going to try it because your 'thinking out of the box' is another person's plain stupid idea but I would think fire a distinct possibility.

[GUMPY]

Thank you. Yup...the dodgy bit is the rotary switch

 

Looking at the actual risks of this..

 

1. If the 220V supply was fed to 12V bulbs...the moment you switched it on, it would pop I imagine?

2. If the 12V supply was fed to 220V bulbs...I guess they would just not light up.

 

Both of these options seem to be low risk.

Have you seen what happens to a 12 v lamp when connected to 230v ?

No I thought not

If you had you wouldn't describe it as low risk.

[DeanS]

I can't remember really but i think it was done with a rotary switch or more likely just two plugs of the same type,one mains and one 12v plugging and unplugging into the light circuits one. All very high tech stuff, probably way above the heads of electricians on here,ahem. (Reliable though, not much to go wrong).

 

And all probably wired up with that lovely old rubber and fabric covered twin twisted flex.

 

 

Bizzard...you say the things I would never dare to say on this forum..LOL...

 

Have you seen what happens to a 12 v lamp when connected to 230v ?

No I thought not

If you had you wouldn't describe it as low risk.

 

 

No I havent. If you say it bursts into flames, then obviously I'd rethink this.

[Chris Pink]

Quite a popular practice 30 odd years ago, mains bulb sockets used for mains bulbs whilst on a landline, and swopping them for 12v bus bulbs which fitted mains sockets when off on a trip. I'm not aware of anyone getting electrocuted.

 

Maybe, just maybe, if a boat had four lights, not the complex wiring beasts they are now and it wouldn't be on a switch.

 

Just the thought of separating the mains and 12V circuits of a boat by the innards of a switch is a Bloody Stupid Idea.

[bizzard]

Bet they blew a load of 12v bulbs though when they forgot to swap them

 

Richard

It might have happened only once probably, the one in the toilet compartment which got forgotten cos someone was on the throne at time of change over.

However people were, poorer therefore more inventive and quite intrepid DIY'ers in those days.

[Chris Pink]

Bizzard...you say the things I would never dare to say on this forum..LOL...

 

 

 

That's because he's winding you (and everyone else) up.

[DeanS]

ok...time for you all to calm down.

 

This was simply an IDEA. I dont want 12V bulbs bursting into flames, so I promise not to do it.

I'll have a dedicated 12V loop, and a seperate 220V loop.

 

You can all relax again.

[Chris Pink]

However people were, poorer therefore more inventive and quite intrepid DIY'ers in those days.

 

...and I have Italian friends who used to switch their washing machine on with a wooden stick but I wouldn't recommend it as SOP

[GUMPY]

 

No I havent. If you say it bursts into flames, then obviously I'd rethink this.

 

Explodes would be a better description

 

If you are using led there will be no difference in light between 12 and 230