Convert 240v wiring to 12v system?

[alifraser88]

Hi there,

I'm about to buy a boat which has been fitted out (electrics-wise) for shore power, with loads of 240v plug sockets everywhere, TVs, Kettles etc, but we don't anticipate or want to be hooked up at all.

What I was wondering was if anyone has had experience in changing this sort of setup over to a 12v, battery-based setup, and what challenges they faced whilst doing so. Is it just a case of removing the external hookup point, connecting the internal wiring to the existing 12v loop (which runs the cabin lights etc) and replacing the 240v sockets with 12v ones? Maybe keep one or two and run through a separate, inverter-containing loop from the battery bank?

 

I don't expect it to be that easy but hopefully it won't mean ripping the walls apart!

 

Cheers,
Alistair

[Robbo]

Really bad idea. 240v volt cable won't handle the current of 12v as well as other safety and BSS issues.

 

If the cablin lights are 12v, what else do you require that's 12v that isn't?

[nicknorman]

I think you should make a list of what 12v services you actually need to add. From the sound of it you already have 12v lighting. Surely you will also have 12v water pump, shower pump etc. You won't be using the electric kettle but presumably a gas one instead. So is it just the TV? What about a fridge?

 

As a general rule mains wiring is not suitable for conversion to 12v as it is probably too thin for long runs. Mains runs at 1/20th the current of 12v for the same power, and even then dropping a volt or so at mains voltage is not an issue, whereas it is at 12v. In particular if you plan a 12v fridge the existing mains wiring will be totally inadequate.

 

So I would retain the mains wiring, add a decent inverter, and try not to have additional 12v services. Modern high efficiency mains fridges + decent inverter may use a bit more power than 12v, but trying to use the existing mains wiring to power the fridge at 12v will be a disaster due to voltage drop.

[alifraser88]

Wow thanks guys! I'll probably leave all the existing wiring in place then and not use it/hide the ugly bits.

 

I suppose the only thing other than lights and pumps would be a couple of 12v ports for phone charging etc. But I might buy solar panels and a digital voltage meter with USB ports or 12v sockets.

 

Cheers,
Alistair

[Paul C]

Yeah just make a list of the items which are 12V, and the items which are 240V. Then you have a simple choice/process:

 

1) Do I need the 240V device while out and about ie not on shoreline

2) If YES, is it easier/cheaper to replace/adapt it to 12V or to fit a decent inverter?

 

 

For example if the list was:

TV

Fridge

Phone charger points

 

Then it would be possible to convert the TV to 12V and fit 12V USB phone charging points, but the fridge might be too expensive to replace so a decent inverter would make sense, then there's no need to alter the telly etc.

 

If you need 12V phone/etc charging, you could fit these around £6 each:

 

 

 

 

 

 

http://www.ebay.co.uk/itm/121415340153?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[Arthur Brown]

The wire that is for 240 will be rated for mains typical currents but currents at 12v will be about 20 times that, and also DC so the cable will struggle with voltage drop and things like the breakers on the dis board will probably not break DC as you hope as they will be rated for AC.

 

As it seems that most of the core services are set up to run from 12v already use the 12v circuits for everything. I would however maintain the 240v circuitry with perhaps a moderate inverter so that you can use 240v if you really need to.

 

While you may not chose to use shoreline now, don't cut off the wires just in case you want to use 240 later, or the next owner may want to use 240.

 

I do have one or two things at home for which there is no 12v charger available -mains makes that easier.

 

I'd also make certain that you have a mains inlet so that you can use a charger when you suddenly need it.

[alifraser88]

Thanks for the advice everyone!

[blackrose]

My advice is not to do away with any systems that you think you'll never use because you never know. It's not like a mains system takes up much physical space.

 

I like to have as many different systems for lighting, heating and hot water as possible. If one system fails or you're working on it then you still have the others.

[George94]

Wow thanks guys! I'll probably leave all the existing wiring in place then and not use it/hide the ugly bits.

 

I suppose the only thing other than lights and pumps would be a couple of 12v ports for phone charging etc. But I might buy solar panels and a digital voltage meter with USB ports or 12v sockets.

 

Cheers,

Alistair

 

Definitely buy solar panels if you are off-grid. There is no better or more cost-effective upgrade you can make to a boat (other than fixing a leak below the waterline).