My Boat Elecrical Plan

[FORTUNATA]

I think I now have a reasonable, but non typical electrical plan for my restoration boat. I often spend most nights going over and over my wiring theory for about an hour before watching a film and winding down. Last night, I had a bit of a brainstorm over issues surrounding loop-in wiring and junction boxes.

Point is I'm going to use A.C. Pure A.C. that is with no inverter. Power will be taken from the shoreline and fed into a consumer unit. The consumer unit will be equipped with MCB's and RCD's and I'll be using ring circuits with lighting circuits added and ring main flex.

Pretty simple really. It's a small boat so I only need about 3 sockets and may even use LED ceiling lights, with stepped down voltage.

Will get my wiring checked by a pro just to be sure when it's done.

Controversial point is my plan to fit a small electric shower as opposed to the standard gas. Higher fuse rate, of course.

D.C. will be installed apart. Will probably involve wind generators and solar panels.

Yes, I think I have all the safety factors taken into account. Cable sizes for ring main and lighting circuits differ as do breaker ratings.

Only thing I'm not sure about is grounding on a fibreglass vessel. My consumer unit will have to be grounded at some fixed point.

Edited May 11, 2012 by FORTUNATA

[Chalky]

I'd be interested where you can find a shore line that can supply the power for an electric shower. Even the small ones are 7kW - 28A ish. You'll need some fairly big cables!

[steelaway]

I'd be interested where you can find a shore line that can supply the power for an electric shower. Even the small ones are 7kW - 28A ish. You'll need some fairly big cables!

 

 

 

That would be a 3.5 Kw shower - you could be busy finding one

 

Alex

[Chalky]

That would be a 3.5 Kw shower - you could be busy finding one

 

Alex

 

7000 / 240 = 29.1

 

3500 / 240 = 14.6

 

7kW is about 29 A ish

[FORTUNATA]

I was assuming I could get a very small, low KW system but it does raise a good point.

I don't fancy gas as an alternative when I already have petrol for engine fuel.

Yes, I have heard of showers tripping out because cables and fuses were underated. I need something low KW ratings.

 

I'd be interested where you can find a shore line that can supply the power for an electric shower. Even the small ones are 7kW - 28A ish. You'll need some fairly big cables!

[Paul C]

Putting the electric shower to one side.....

 

1) What AC mains devices are you planning to run? (eg lights - all lights? Some? What else?)

2) Are you happy for these to be unavailable without the shore power line, ie when you're cruising in the boat and/or mooring away from 'base'.

 

If the answer to (2) is 'no', then you need to either fit an inverter too or revisit (1) and specify some of the devices you've earmarked as mains power, 12V power.

[FORTUNATA]

Here ya go:

"Electric Shower Hoter Jet Compact Instant Hot Water Heater 220V 3.5KW - Ideal For Caravan & Boats"

 

However, there was the following customer comment:

 

"This unit was purchased for use in a workshop washroom as a means of heating water to wash hands only. Purchased this unit and fitted it in accordance with the manufacturers instructions and building regulations. When switched on the heat was minimal and decreased with water pressure. The only time the water got hot was on low pressure. The item was purchased to heat water for washing hands only. There is no way this unit would be good enough to heat water at speed for a shower. To top this within two days of being installed the unit started to leak from the body seam, as the pressure is regulated by a stop cock and has to be turned down low TO WARM WATER this is not a case of too high mains pressure. Considering the unit has electrical components and has failed so easily this constitutes a Health and Safety Hazard, and cannot now be used. Along with the fact there are no contact details for either making a complaint or asking for a refund, or replacement, or even an exchange. I would suggets THIS IS A DANGEROUS PRODUCT DO NOT PURCHASE"

 

Yes, the design would be for fixed mooring so it's not an issue over cruising. 2 different systems with DC for cruising.

As to 3.5kw showers, I can understand the complaint I listed as these units do cool under pressure. I have used one as a hand-wash and if opened up a lot the water cools. I think, though, the customer had a faulty unit as they shouldn't leak.

Should be able to get a reasonable 3.5 kw unit but will have to watch water pressure and my cable and fuse needs to be spot on.

 

Putting the electric shower to one side.....

 

1) What AC mains devices are you planning to run? (eg lights - all lights? Some? What else?)

2) Are you happy for these to be unavailable without the shore power line, ie when you're cruising in the boat and/or mooring away from 'base'.

 

If the answer to (2) is 'no', then you need to either fit an inverter too or revisit (1) and specify some of the devices you've earmarked as mains power, 12V power.

[Chalky]

We had a 7 kW shower in one bathroom at home. It never got used in the winter because it couldn't heat the water fast enough and in the summer it was pathetic. How about something like the caravan boilers that do gas and electric? Or fit a calorifier with a small immersion heater. That way you can use a low power feed to heat the tank and build up the temperature over a period of time rather than needing it instantaneously.

[bizzard]

Or a cafe size electric tea Urn,it would hold enough hot tea or plain water for a good shower.The shower head tube would fit where the tap is. Tea is good for the complexion too.You could call it the ''Typhoon''.

[Paul C]

......... How about something like the caravan boilers that do gas and electric? Or fit a calorifier with a small immersion heater. That way you can use a low power feed to heat the tank and build up the temperature over a period of time rather than needing it instantaneously.

 

x2

 

Just make sure that your mains electrics, and shoreline supply etc, are up to the job of handing the ~3kW or so of an immersion heater. And don't switch an electric kettle (or other large electrical consumer) on while its on or you'll trip it out!

[mickp]

i would go down the immersion heater route,i use a2kw jobby but a couple of friends use 1kw elements,make sure you can only use on shore ,so isolate from inverter circuit

[Guest]

When instanatneous electric showers first appeared on the market, they were around 3Kw (they were also going to kill everybody and "were banned in some parts of america" ). They gave a very low volume of water at a very modest temperature. Better than nothing I suppose, but not recommended. Most are in the region of 7kW and higher today, but our one at home can be switched to a lower power. I assume this is half power (3.5Kw) though it is rather cool at this setting. I think as others have stated, you are looking at an immersion and electric pump system.

 

There are still 3Kw handwash units; we have a Redring one at work which could be converted to a shower with a little ingenuity, though you wouldn't get much of a shower from it.

Edited May 11, 2012 by Guest

[DeanS]

Hello.

 

I think most marina bollards will supply a max of around 15Amps. An elec shower would probably not work ...it would trip the mains supply .

[Chalky]

i would go down the immersion heater route,i use a2kw jobby but a couple of friends use 1kw elements,make sure you can only use on shore ,so isolate from inverter circuit

 

I have a pair of MCBs on my mains input with a switch to select between them. 1 is 6A, the other is 16A. It allows me to set a trip current for my incoming supply at the same value or less than the supply I'm connected to so hopefully my breakers should trip before the one I'm connected to.

[Arthur Brown]

In reality a marina bollard will supply 5 - 15A and will not even nearly support an electric instant shower, which tend to be 7Kw and above. Usually a feed rating of 45a is suitable with it's own MCB and RCD. This would be a most unusual marina bollard!

 

For an instant shower it's possible that one or two eberspacher heaters would create enough flow of hot enough water, BUT they should be run with treated water not shower water.

 

SO whether you chose electric or oil heating the calorifier tank is your best friend, heat a tank of water over an hour or two then shower in it over a minute or two.

 

With the environment of a Plastic boat I'd be very cautions about the earth type and the CPC continuity for safety purposes.

[Guest]

Quite good feedback: http://www.amazon.co.uk/gp/offer-listing/B0043QR9RY/ref=asc_df_B0043QR9RY7503178?ie=UTF8&condition=new&tag=nextag26680-21&creative=22278&creativeASIN=B0043QR9RY&linkCode=asm

Edited May 11, 2012 by Guest

[RLWP]

Hello.

 

I think most marina bollards will supply a max of around 15Amps. An elec shower would probably not work ...it would trip the mains supply .

 

What has happened to you Dean? This is exactly the sort of mad-cap scheme you used to come up with. And now, here you are offering practical reasons why something won't work

 

 

Richard

[ditchcrawler]

What has happened to you Dean? This is exactly the sort of mad-cap scheme you used to come up with. And now, here you are offering practical reasons why something won't work

 

 

Richard

He has changed a lot in 12 months

[Biggles]

Me thinks the OP needs to rethink the whole idea of an electric shower on a boat unless he has a massive generator and or battery bank and 2 or 3 inverters linked.

 

As its a small boat I would think this amount of kit would either sink it or leave little room for a shower, or indeed anything else .

 

I would love to see how this is made to work.

[Guest]

Me thinks the OP needs to rethink the whole idea of an electric shower on a boat unless he has a massive generator and or battery bank and 2 or 3 inverters linked.

 

As its a small boat I would think this amount of kit would either sink it or leave little room for a shower, or indeed anything else .

 

I would love to see how this is made to work.

I tend to agree that it is not the best way forward.

 

Can be done with a 3kW unit (assuming normally rated shore supply), but as others and myself have explained the temp/flow is mediocre at best. In winter I expect it would be feeble. That was certainly my experience with the early 3kW domestic units in the '70's when I used to fit them.

 

I find 7kW to be the bare minimum for an electric shower in my home. Higher kW rating still is better in winter.

Edited May 12, 2012 by Guest

[smileypete]

Controversial point is my plan to fit a small electric shower as opposed to the standard gas. Higher fuse rate, of course.

D.C. will be installed apart. Will probably involve wind generators and solar panels.

Yes, I think I have all the safety factors taken into account. Cable sizes for ring main and lighting circuits differ as do breaker ratings.

Only thing I'm not sure about is grounding on a fibreglass vessel. My consumer unit will have to be grounded at some fixed point.

For shoreline only use you may be better off with a properly installed 2kW 15L 'undersink' heater, see Screwfix or Ebay. Or just get a calorifer. Also look into using a 'garage consumer unit' which is fairly compact and has RCD and usually 16A MCB.

 

Bear in mind if your boat has a 16A MCB and wired with 16A cable it does not NEED a bl**dy 'ring main'! Also standard mains electrical parts are not designed for use with flexible fine stranded cable, it's best to use crimp on ferrules on the cable ends.

 

Have a look at BSS with regard to mains to DC cable spacing requirements and other stuff.

 

cheers,

Pete.

smpt

[Guest]

For shoreline only use you may be better off with a properly installed 2kW 15L 'undersink' heater, see Screwfix or Ebay. Or just get a calorifer. Also look into using a 'garage consumer unit' which is fairly compact and has RCD and usually 16A MCB.

 

Bear in mind if your boat has a 16A MCB and wired with 16A cable it does not NEED a bl**dy 'ring main'! Also standard mains electrical parts are not designed for use with flexible fine stranded cable, it's best to use crimp on ferrules on the cable ends.

 

Have a look at BSS with regard to mains to DC cable spacing requirements and other stuff.

 

cheers,

Pete.

smpt

Good point re. ring main, my boat has radial circuits for the 240V sockets. I was warned (possibly Gibbo) that ring mains and inverters weren't a good idea, and on thinking about it couldn't see the need for a ring anyway (16A MCB.)Our obsession for ring mains comes from houses etc.

 

Good point re. cable ends, I used boot lace ferrules on mine.

Edited May 12, 2012 by Guest

[FORTUNATA]

"I would love to see how this is made to work."

 

So would I. Maybe I'm getting a bit over optimistic in my schemes. In fact, when discussing the plan today in an electrical store the staff started to titter. Problem is cable limitations and probable feeble capacity of a 3.5 kw shower.

 

Me thinks the OP needs to rethink the whole idea of an electric shower on a boat unless he has a massive generator and or battery bank and 2 or 3 inverters linked.

 

As its a small boat I would think this amount of kit would either sink it or leave little room for a shower, or indeed anything else .

 

I would love to see how this is made to work.

[DeanS]

"I would love to see how this is made to work."

 

So would I. Maybe I'm getting a bit over optimistic in my schemes. In fact, when discussing the plan today in an electrical store the staff started to titter. Problem is cable limitations and probable feeble capacity of a 3.5 kw shower.

 

Are you sure you and I arent related? Have you considered a recirculating shower?

[FORTUNATA]

I need to chew it over very carefully. It may be doable but only just.

 

Are you sure you and I arent related? Have you considered a recirculating shower?