Electrics. Where to start.

[truckcab79]

10 hours ago, Richard10002 said:

Even if you are off grid completely, you will need the shore power connection to connect your generator in winter. Money well spent.

 

I spend 3 or 5 nights a week on board a 45ft narrowboat. 400W of solar keeps me topped up for most of March to September- if the sun isn't good for a few days, I run the genny.... perhaps 3 or 4 times over the period. 

 

I think I would have got 600w to possibly avoid running the genny in Spring/Summer. 

 

October to March I run the genny to fill up about every 3 days on board. Solar is pretty much a token.

 

 

 

Many thanks. And a good guide for what solar I think I probably need to go for, and in line with that YouTube chap who installs ‘500 for narrow boats, 1,000 for wide beams’.  

If you have an inverter for minimal use let me know what you have (wife’s hairdryer and not much else), and you’ve probably answered everything I need.  👍

[Jen-in-Wellies]

21 minutes ago, truckcab79 said:

If you have an inverter for minimal use let me know what you have (wife’s hairdryer and not much else), and you’ve probably answered everything I need.

A hairdryer is not minimal use! 1600W is typical. They are high power consumers, but fortunately, only for a limited time. 10 minutes at 1600W is roughly 27Ahrs out of the batteries.

Beware of YouTube channels. Some are good, but the only qualification for starting one is ownership of a baseball cap to wear while in front of the camera.

[jonathanA]

15 hours ago, MtB said:

There is a drawback to this style of fuseboard, I find.

 

All the connectors on the back are spade tags for you to connect onto with push on crimp connectors. Once you've done this with a 20 or 30  surprisingly fat wires all pushed on to the spade terminals, it requires a fair amount of force to shove it into the exact right place as all the wires get bent into position. Hopefully none will actually fall off or get bent off, but they can. And it you unscrew it to withdraw it to add something, some will almost definitely come off the spades. DAMHIK.

 

I scrapped mine in the end and fitted a proper domestic consumer unit with DC rated breakers, and now I can get at the gizzards of it without disturbing any of the other 12 circuits I'm not working on. 

 

 

Agree it can be a problem if you don't know how to form and lace* a nice wiring loom. (Stick to plumbing 😀)

 

Actually the bigger problem with most of these type of panels is the lack of sufficiently beefy supply busbar. Tends to be 2.5mm2 wire looped from cct breaker to cct breaker. With just a spade connector or two to link to the battery feed.

 

*lace - doubt anyone uses string now but cable ties 

Edited September 10, 2023 by jonathanA
Lace

[MtB]

1 hour ago, truckcab79 said:

Many thanks. And a good guide for what solar I think I probably need to go for, and in line with that YouTube chap who installs ‘500 for narrow boats, 1,000 for wide beams’.  

 

"How much solar do I need?" is not a question that cannot really be meaningfully answered, due to what we call "WotEver's Law". 

 

WotEver's Law states: "However much solar you install, it will be too much in summer and too little in winter."

 

This is due to the massive swing in output of solar with the passing of the seasons. In high summer, the output is 10-20 times the output in mid winter, so in summer you'll probably find an 80W panel more than adequate and in winter, 1kW will hardly keep up. 

 

The more solar you have though, the earlier the date in the year when the solar has enough output to take over from engine running etc, and the later into the autumn it will carry on working. So bottom line in, just fit as much as will fit on the roof. 

 

 

12 minutes ago, jonathanA said:

Agree it can be a problem if you don't know how to form and lace* a nice wiring loom. (Stick to plumbing 😀)

 

When I was an apprentice engineer I was trained in loom construction and lacing by Decca Radar and I've NEVER seen any boat wired to the standard we worked to.  

 

And you no doubt appreciate the big problem with a neatly laced loom is how difficult is it is to add more wires. Also identifying each conductor turns into a problem pretty quickly as you rapidly run out of colours with more than about ten wires in it. At least with the "rat's nest" method favoured by most marine electricians you stand a chance of following each wire, should you need to!

Edited September 10, 2023 by MtB
Clarify a point.

[truckcab79]

Yep.  Found a good site yesterday with a chart showing the huge difference between June and September to March.  I’m going to base it on 500 I think as a starting point for planning. 
 

Still looking for a sensible answer on inverter size for light use.  Might just base it on the fact that a hairdryer or a tool battery charger is probably all that will ever be run on it. I’m only going to add probably two sockets and they’ll get very little use. Fridge, TV if we have one, stereo if it’s not just a rechargeable radio (I’ll probably install a ‘car stereo’ type with a couple of speakers in the ceiling), will all be 12v.  

[DShK]

Hair dryer is not light use. 2-3kw inverter depending on the pull of your appliance. Check it with a power plug. Don't toe the rated wattage (you want to be looking at VA rating too not just wattage)

 

You'll get away with a much smaller inverter if you do away with the hair dryer

Edited September 10, 2023 by DShK

[Alan de Enfield]

14 minutes ago, truckcab79 said:

Might just base it on the fact that a hairdryer or a tool battery charger is probably all that will ever be run on it. I’m only going to add probably two sockets and they’ll get very little use. Fridge,......................

 

If you are looking to install a 240v fridge, then of all the items listed the fridge will be the one that determines the size of inverter.

 

You may think that a 40w fridge needs a smaller inverter than a 1500w hairdryer - wrong !

Different sort of loads.

 

Yes the fridge is only 40w when running, but being an inductive load, everytime it stops and restarts (3 or 4 times an hour) it will have a huge 'surge' and need (probably) require a 2000w inverter.

[DShK]

1 minute ago, Alan de Enfield said:

 

If you are looking to install a 240v fridge, then of all the items listed the fridge will be the one that determines the size of inverter.

 

You may think that a 40w fridge needs a smaller inverter than a 1500w hairdryer - wrong !

Different sort of loads.

 

Yes the fridge is only 40w when running, but being an inductive load, everytime it stops and restarts (3 or 4 times an hour) it will have a huge 'surge' and need (probably) require a 2000w inverter.

A "soft start" device would potentially lower this, not used one myself but looked into it for AC...

[truckcab79]

23 minutes ago, Alan de Enfield said:

 

If you are looking to install a 240v fridge, then of all the items listed the fridge will be the one that determines the size of inverter.

 

You may think that a 40w fridge needs a smaller inverter than a 1500w hairdryer - wrong !

Different sort of loads.

 

Yes the fridge is only 40w when running, but being an inductive load, everytime it stops and restarts (3 or 4 times an hour) it will have a huge 'surge' and need (probably) require a 2000w inverter.

Pretty sure it’ll be a 12v fridge. They’re comparatively expensive but not horrendously so.  

[Ronaldo47]

1 hour ago, jonathanA said:

Agree it can be a problem if you don't know how to form and lace* a nice wiring loom. (Stick to plumbing 😀)

 

Actually the bigger problem with most of these type of panels is the lack of sufficiently beefy supply busbar. Tends to be 2.5mm2 wire looped from cct breaker to cct breaker. With just a spade connector or two to link to the battery feed.

 

*lace - doubt anyone uses string now but cable ties 

As a young engineer in the late 1960's I was taught how to make up cable looms using lacing cord, but nowadays I tend to use plastic spiral wrapping, it's reusable and not expensive. I've just got some from CPC: 25m of 15mm cost £8.99 plus VAT.  Other suppliers and other sizes are available! 

Edited September 10, 2023 by Ronaldo47
typos

[Alan de Enfield]

12 minutes ago, truckcab79 said:

Pretty sure it’ll be a 12v fridge. They’re comparatively expensive but not horrendously so.  

 

£600 ish, for a decent one, or you can of course buy a 'cheapy' off ebay for £400 ish.

 

Buy a recognised 'boaty' brand like Waeco / Dometic and buy once.

 

When installing a 12v fridge there are two things to do 'right'

 

1) Ventilation all around, even put a fan thru the floor and use the bilge air for cooling.

2) Follow the manual for cable sizes, go even larger, do not underspec the wiring or you will have problems. If you think it looks OK, then it isnt.

 

 

[truckcab79]

13 minutes ago, Alan de Enfield said:

 

£600 ish, for a decent one, or you can of course buy a 'cheapy' off ebay for £400 ish.

 

Buy a recognised 'boaty' brand like Waeco / Dometic and buy once.

 

When installing a 12v fridge there are two things to do 'right'

 

1) Ventilation all around, even put a fan thru the floor and use the bilge air for cooling.

2) Follow the manual for cable sizes, go even larger, do not underspec the wiring or you will have problems. If you think it looks OK, then it isnt.

 

 

Cheers. Seems to be loads around under £400 from various camper and marine sites.  Still need to plan layout so not sure what size we’ll be looking for but the whole kitchen will be tiny. Been looking at fridge / freezers but in reality we wouldn’t miss a freezer at home so fridge with ice box type thing would probably be all we’d need.  Probably fridge only I suspect.  

[Richard10002]

1 hour ago, Alan de Enfield said:

 

Buy a recognised 'boaty' brand like Waeco / Dometic and buy once.

 

When installing a 12v fridge there are two things to do 'right'

 

1) Ventilation all around, even put a fan thru the floor and use the bilge air for cooling.

2) Follow the manual for cable sizes, go even larger, do not underspec the wiring or you will have problems. If you think it looks OK, then it isnt.

 

 

When my 15 year old fridge failed in 2016, I bought a Waeco - ventilation and fan in the floor. When my Waeco failed in 2020, I bought a Waeco as I didnt want to risk an ebay cheapy.

 

So far so good but, if my current Waeco fails, I will be buying a "cheapy"...... probably Alpicool, but we'll see what's around when it happens..

[StephenA]

23 hours ago, David Mack said:

Think carefully before installing your wiring behind the hull or cabin lining. It will make subsequent alterations, and fault-finding in the case of problems, much more difficult.

And if you have polystyrene insulation you MUST avoid all contact between the polystyrene and the pvc cable sheath/insulation, which means cable behind the lining has to be fully ducted anyway.

This diagram from Tony Brooks' notes shows the usual locations for wiring.

http://www.tb-training.co.uk/MarineE03.html#RUNNING THE CABLES

My choice would be location B, but with a removable cover fitted to the bottom.

 

 

All of our cables sit basically on a cable tray in position B

[cuthound]

5 hours ago, jonathanA said:

Agree it can be a problem if you don't know how to form and lace* a nice wiring loom. (Stick to plumbing 😀)

 

Actually the bigger problem with most of these type of panels is the lack of sufficiently beefy supply busbar. Tends to be 2.5mm2 wire looped from cct breaker to cct breaker. With just a spade connector or two to link to the battery feed.

 

*lace - doubt anyone uses string now but cable ties 

 

I remember learning to lace up wiring looms at college in 1970.

 

Not sure if I could remember how now. Spiral wrap and cable ties killed this particular skill off.

Edited September 10, 2023 by cuthound
Phat phingers

[truckcab79]

Those using Position B in that earlier diagram. What are you using to run and secure them in.  Inverted commercial cable trays?  

[cuthound]

16 minutes ago, truckcab79 said:

Those using Position B in that earlier diagram. What are you using to run and secure them in.  Inverted commercial cable trays?  

 

My first shareboat used inverted PVC trunking screwed into the ply that lined the underside of the gunwale. The lid formed the bottom of the trunking and a piece of veneered ply was glued to the exposed side of the trunking to make it look nice.

[truckcab79]

20 minutes ago, cuthound said:

 

My first shareboat used inverted PVC trunking screwed into the ply that lined the underside of the gunwale. The lid formed the bottom of the trunking and a piece of veneered ply was glued to the exposed side of the trunking to make it look nice.

So the normal snap close white plastic stuff?  Might try to find some commercial stuff that leaves them all nicely exposed (and then cover with decorated panel. 

[cuthound]

4 minutes ago, truckcab79 said:

So the normal snap close white plastic stuff?  Might try to find some commercial stuff that leaves them all nicely exposed (and then cover with decorated panel. 

 

Yes, the normal trunking. it was 50 wide by 25 deep IIRC (it was over 20 years ago 😂).

[Tracy D'arth]

1 hour ago, truckcab79 said:

So the normal snap close white plastic stuff?  Might try to find some commercial stuff that leaves them all nicely exposed (and then cover with decorated panel. 

Or this type

https://duckduckgo.com/?q=plastic+cable+tray&atb=v314-1&iax=images&ia=images&iai=https%3A%2F%2Fimage.made-in-china.com%2F2f0j00ndhtBmecNskJ%2FQuick-Deliver-Date-25X25mm-PVC-Cable-Trunking-for-Electrical.jpg

[LadyG]

10 hours ago, truckcab79 said:

Yep.  Found a good site yesterday with a chart showing the huge difference between June and September to March.  I’m going to base it on 500 I think as a starting point for planning. 
 

Still looking for a sensible answer on inverter size for light use.  Might just base it on the fact that a hairdryer or a tool battery charger is probably all that will ever be run on it. I’m only going to add probably two sockets and they’ll get very little use. Fridge, TV if we have one, stereo if it’s not just a rechargeable radio (I’ll probably install a ‘car stereo’ type with a couple of speakers in the ceiling), will all be 12v.  

I don't think your requirements are my idea of light use!

There are low power hair dryers, indeed 12v, I believe. My car radio has been fitted in the stern, but the speakers are in the front, so I can't really control it easily.

[truckcab79]

15 minutes ago, LadyG said:

I don't think your requirements are my idea of light use!

There are low power hair dryers, indeed 12v, I believe. My car radio has been fitted in the stern, but the speakers are in the front, so I can't really control it easily.

Yep. Hair-dryer probably the wrong example.  She’ll have to use a towel. 😂

Just now, truckcab79 said:

Yep. Hair-dryer probably the wrong example.  She’ll have to use a towel. 😂

Might convince her to have a 12v hair-dryer but the reviews of any I’ve looked at are pretty poor.  

17 minutes ago, LadyG said:

My car radio has been fitted in the stern, but the speakers are in the front, so I can't really control it easily.

There are plenty of basic but decent enough head units on the market that come with remote controls. Think I paid £20 for one for my old van when I needed something at short notice.  Decent sound too.  Well for £20 anyway. 

[MtB]

14 minutes ago, truckcab79 said:

Yep. Hair-dryer probably the wrong example.  She’ll have to use a towel. 😂

Might convince her to have a 12v hair-dryer but the reviews of any I’ve looked at are pretty poor.  

 

Reducing the voltage doesn't reduce the power, which is what the batteries care about.

 

A 1600w 12V dryer will draw 133A from the batteries. A 240V dryer via an inverter 100% efficient (no such thing) would draw the same. But taking inverter inefficiency into account it would probably draw about 160A.

 

So there are two marginal benefits to switching to a 12V dryer. 

 

1) You get rid of the (fairly small) inverter losses

2) You will find 12V hair dryers tend to be much lower power so they don't need a cable the size of battery interconnects. The corollary is they are not going to work as well and the power of the heater inside is what makes the thing dry hair. Mostly! 

 

 

Edited September 10, 2023 by MtB
sp

[truckcab79]

On 10/09/2023 at 20:22, LadyG said:

My car radio has been fitted in the stern, but the speakers are in the front, so I can't really control it easily.

There are plenty of basic but decent enough head units on the market that come with remote controls. Think I paid £20 for one for my old van when I needed something at short notice.  Decent sound too.  Well for £20 anyway. 
 

 

 

Just chucking in random questions as they come to me. Hope nobody minds. Better than starting 100 thread I’m sure.  
 

Im a sucker for new tools and hate borrowing or hiring. They’re  tax deductible through the business anyway so I tell myself they’re ‘free’.
 

As part of my electrical planning I’ll need some big crimpers for  battery cables and the like.  Looked at the ‘bolt cutter’ type but they’re bulky and limited range.  Then I found the little hydraulic ones which seem ideal.  Smallest one does 4-70mm.  BSS says battery cable minimum 25mm so more than enough capacity without going to the next size up I assume. Any thoughts?  
 

[Alan de Enfield]

70mm2 is only rated at ~200 / 230 amps, so if you are going for a large-ish (or 'big') Inverter you will need to go larger.

 

eg a 3kw inverter will be drawing around 300 amps.

 

70mm2 will be plenty big enough for 99.9% of what you are likely to be doing.