Mains Power on Board

[Stemar]

I'm thinking of installing mains electricity on Jazzcat. I understand how the circuits work and can wire things safely, but am less sure about cable sizes and a few other details.

I already have a box with a double pole RCD and a couple of 16amp circuit breakers, which I'll install as close as practicable to the supply plug (Is IP44 adequate for mounting out of spray but in the rain?).

Since I have the two breakers, I'm thinking of a circuit for each hull, with a couple of double sockets on each, on the basis that it's always better to have more rather than less, though the only serious current draw would be a fan heater in winter and, possibly a reasonably chunky battery charger, though this will come later.

Since I have 16 amp breakers and no long cable runs, ISTM that 1.5 amp cable would be more than adequate, and I plan on using heat resistant flexible cable, rather than house cable, for vibration resistance.

Any thoughts please?

 

[Tranona]

Just done this, but with very short cable runs and used 1.5A cable. 2 circuits, 6A for mains battery charger and 16A for a ring main with 1 single and 1 double. with USB outlets. Suggest you do the same rather than run 2 separate rings. the CU I used (type usually sold for garage/workshops) has room for an additional circuit breaker should I want to add a circuit for an immersion in a calorifier.

Also added a galvanic isolator and earthed the system (from the CU) to a dedicated button anode in line with the latest standards.

 

[Boathook]

I used 2.5mm 3 core flex for my electrics with both hulls from a single 16 amp circuit breaker. Another circuit breaker supplies the fridge and battery charger. Most marinas including my mooring are limited to 16 amps only.
The fuse box also has a double pole RCD.

 

[PaulRainbow]

Forget 1.5mm cable. Get some 2.5mm arctic flex, job done.

No need for a ring main, a radial circuit is fine for small installations.

 

[VicS]

Forget 1.5mm cable. Get some 2.5mm arctic flex, job done.

No need for a ring main, a radial circuit is fine for small installations.

Absolutely.

Ring mains ( or ring circuits as they are now known) were a strange invention unique to the UK back in about 1940. with little or no good reason for their installation today, even in peoples homes.
Anyone installing ring circuits should be aware of the additional tests which should be carried out.

 

[LadyInBed]

Any thoughts please?

Yes. Fit double sockets, don't bother with singles.
I also put in a mains led strip light circuit (inc engin bay) and wall mounted fan heaters in each cabin.

 

[Boathook]

Yes. Fit double sockets, don't bother with singles.
I also put in a mains led strip light circuit (inc engin bay) and wall mounted fan heaters in each cabin.

I agree with double sockets where possible but I prefer to use the boats 12 volt lights rather than mains. Fan heaters in each cabin is a good idea but can you get low wattage ones so you don't keep tripping the circuit breakers.

 

[VicS]

I agree with double sockets where possible but I prefer to use the boats 12 volt lights rather than mains. Fan heaters in each cabin is a good idea but can you get low wattage ones so you don't keep tripping the circuit breakers.

You can get fan heaters with switched power ratings. Maybe an electrician could "fix" one so that it only operates on the lowest setting.
I have been looking at fan heaters for the bathroom. Some can be restricted to 1kW during installation.

 

[coopec]

I'm not sure that I understand this thread.

No need for a "Ring Main". What's that? (I'm in Australia)

When I installed my 3000W/6000W 24V/240V inverter I just went to the hardware store and bought X3 extension cords and secured them in place -

• X1 microwave
• X1 Galley/jug/cooking hob
• X1 Bread-maker/General

A household electrician/boatie mate had a look at what I had done and said it was quite safe but it is not the way he would have wired as he could have done it cheaper.
(I plan to look at install a RCD device)

Some time in the future If I wanted to use shore power I'd use a switch to change from Inverter to shore power.

Maybe I misunderstand the thread?

 

[Boater Sam]

If you are on salt especially the cable should be tinned copper to avoid corrosion.
A ring main is unsuitable for your boat so ignore ( look it up on the net if you wish, then forget it )
Use 2.5mm flexible cable, often sold as Arctic cable for some reason. The extra copper makes connections better and it is less likely to fracture in use. Double back all stripped copper ends if you can so that you have more copper in the terminal. You should still be able to get 3 wires in the socket terminals but no more.
A Galvanic Isolator in the incoming earth cable is vital if you spend lots of time on the shore line in marinas or near other connected boats else your underwater metal and/or your hull if steel is at risk of disappearing.

 

[lustyd]

A Galvanic Isolator in the incoming earth cable is vital if you spend lots of time on the shore line in marinas or near other connected boats else your underwater metal and/or your hull if steel is at risk of disappearing.

I believe that's only an issue if you have a grounding point on board, which not all boats have. More common with gensets and inverters.

 

[Refueler]

May I suggest a couple of publications ??

James Yates : Boat Electrics

ISBN : 1-86126-280-5

Alastair Garrod : Electrics Afloat (...... as recc'd and sold by PBO themselves).

ISBN : 0-7136-6149-6

Why do I recc'd ?? For one very simple reason ... the possible dangers that can occur due to different wiring standards EVEN between UK based Marinas etc.
Garrods book - I particularly recc'd as it simply and without too much techy gubbins gets the message across ... and also puts right many misconceptions about Lead Acid batterys .....

 

[PaulRainbow]

If you are on salt especially the cable should be tinned copper to avoid corrosion.

The only place i've ever seen a boat wired with tinned cable is on the internet. In the real World, untinned copper is used, with the exception of areas more likely to be damp. I work on boats with wiring dating back to the 60's, wired with standard copper cable, no issues with any wiring in dry areas.

Are all cars and houses in coastal towns wired with tinned cable ?

A ring main is unsuitable for your boat so ignore ( look it up on the net if you wish, then forget it )

Not unsuitable, just unnecessary.

Use 2.5mm flexible cable, often sold as Arctic cable for some reason.

Lots of variations of 2.5 flex, Arctic being just one. It is called Arctic cable because it can endure temperatures as low as -40c and remain flexible. It's the go to cable for general outdoor use.

The extra copper makes connections better and it is less likely to fracture in use. Double back all stripped copper ends if you can so that you have more copper in the terminal.

Even if the cable is folded over, the screws still chew the thin strands. Better to use crimped bootlace ferules.

You should still be able to get 3 wires in the socket terminals but no more.

You won't get three doubled over 2.5mm wires in a socket terminal. That said, you should not need to do so, unless you are fitting spurs, which i'd avoid on a boat as much as possible, better to stick with a standard radial circuit on a mid to large sized installation. For a typical small boat installation, where there are a small amount of sockets, it's often simpler to run a separate cable from the consumer unit to each socket.

A Galvanic Isolator in the incoming earth cable is vital if you spend lots of time on the shore line in marinas or near other connected boats else your underwater metal and/or your hull if steel is at risk of disappearing.

As mentioned in post #11, a galvanic isolator is only needed of the Earth is connected to the water.

 

[PaulRainbow]

I'm not sure that I understand this thread.

No need for a "Ring Main". What's that? (I'm in Australia)

As the forums resident Google expert Clive, surprised you've not looked it up

When I installed my 3000W/6000W 24V/240V inverter I just went to the hardware store and bought X3 extension cords and secured them in place -

• X1 microwave
• X1 Galley/jug/cooking hob
• X1 Bread-maker/General

A household electrician/boatie mate had a look at what I had done and said it was quite safe but it is not the way he would have wired as he could have done it cheaper.
(I plan to look at install a RCD device)

Some time in the future If I wanted to use shore power I'd use a switch to change from Inverter to shore power.

Maybe I misunderstand the thread?

Sorry, but this sounds like a potentially lethal installation. This would not comply with current regs in any civilised country.

 

[Daydream believer]

This would not comply with current regs in any civilised country.

Western Australia?? ?

 

[Boater Sam]

The only place i've ever seen a boat wired with tinned cable is on the internet. In the real World, untinned copper is used, with the exception of areas more likely to be damp. I work on boats with wiring dating back to the 60's, wired with standard copper cable, no issues with any wiring in dry areas.

Are all cars and houses in coastal towns wired with tinned cable ?



Not unsuitable, just unnecessary.



Lots of variations of 2.5 flex, Arctic being just one. It is called Arctic cable because it can endure temperatures as low as -40c and remain flexible. It's the go to cable for general outdoor use.



Even if the cable is folded over, the screws still chew the thin strands. Better to use crimped bootlace ferules.



You won't get three doubled over 2.5mm wires in a socket terminal. That said, you should not need to do so, unless you are fitting spurs, which i'd avoid on a boat as much as possible, better to stick with a standard radial circuit on a mid to large sized installation. For a typical small boat installation, where there are a small amount of sockets, it's often simpler to run a separate cable from the consumer unit to each socket.



As mentioned in post #11, a galvanic isolator is only needed of the Earth is connected to the water.

Plenty of correct info there but your usual facetious comments and style I find jarring as is normal with your posts. I will put you back on ignore, thank you.
I don't know why I bother but I do like to try to the best of my limited ability to assist those who ask sensible questions. Perhaps we should all shut up and leave it to the few on here who are always totally correct and know it all.

 

[Boathook]

Plenty of correct info there but your usual facetious comments and style I find jarring as is normal with your posts. I will put you back on ignore, thank you.
I don't know why I bother but I do like to try to the best of my limited ability to assist those who ask sensible questions. Perhaps we should all shut up and leave it to the few on here who are always totally correct and know it all.

It's just @PaulRainbow style. If there are bits I don't like I just ignore those comments. About the only people using tinned wire on boats seem to be the DIYers which includes myself.

 

[Refueler]

The only place i've ever seen a boat wired with tinned cable is on the internet. In the real World, untinned copper is used, with the exception of areas more likely to be damp. I work on boats with wiring dating back to the 60's, wired with standard copper cable, no issues with any wiring in dry areas.

Are all cars and houses in coastal towns wired with tinned cable ?



Not unsuitable, just unnecessary.



Lots of variations of 2.5 flex, Arctic being just one. It is called Arctic cable because it can endure temperatures as low as -40c and remain flexible. It's the go to cable for general outdoor use.



Even if the cable is folded over, the screws still chew the thin strands. Better to use crimped bootlace ferules.



You won't get three doubled over 2.5mm wires in a socket terminal. That said, you should not need to do so, unless you are fitting spurs, which i'd avoid on a boat as much as possible, better to stick with a standard radial circuit on a mid to large sized installation. For a typical small boat installation, where there are a small amount of sockets, it's often simpler to run a separate cable from the consumer unit to each socket.



As mentioned in post #11, a galvanic isolator is only needed of the Earth is connected to the water.

I often have issues as many know with Paul ... but I have to applaud his post as being real world .....

I have had stick for using common copper based cable ... lack of earth to water ... but have such and I have no risk to myself or others as a result. I no longer have any evidence of Galvanic Corrosion ... my engine and shaft are fine ....

My lack of earth to water is based on not only using UK marinas for many years - but also using EU / Baltic marinas ... BUT I am careful to make sure I am not creating a path elsewhere ....

 

[coopec]

As the forums resident Google expert Clive, surprised you've not looked it up



Sorry, but this sounds like a potentially lethal installation. This would not comply with current regs in any civilised country.

If you reckon you guys know it all why did you go for a "Ring Mains" (Australia never used them)

Can you quote the Regulations that ban the use of domestic cabling (extension cord) for the internal 240V cabling of a yacht.
What do you suggest should be used instead? (The electrical tradesman approved the safety aspect of what I've done so I'm not terribly interested in what you think)

 

[Refueler]

It's just @PaulRainbow style. If there are bits I don't like I just ignore those comments. About the only people using tinned wire on boats seem to be the DIYers which includes myself.

According to many posts over the years ... I would suggest posts are telling DIY'rs to follow 'Professional' electricians use of Tinned ..... not other way round.

I agree Paul can 'rub wrong way' ..... as can I and many others on these Forums. Such is life. If we were in a pub and having the discussion - it would be different but we aren't.

Spinnaker Pub - Hamble ..... I was told I knew nothing about correcting for current - so I called the guy a twat ... he laughed - we had another pint.
Try that here !!