Calling all sparkies

[Pladdatoo]

Am undertaking a bit of a re-wire, so have a few questions to ask. I am looking for some best practice advise, so please be patient, I am keen to learn and do it well and don't want to just hand it over to an expert and not become intimate with my boats electrics.

Apart from replacing old wiring (some of which appears to be domestic household 3-core),I am installing a Nasa Battery Monitor, along with a VSR (I am on a 1xhouse/1 x starter config). This requires a bit of alteration to my battery cabling as the current setup is an 12AB switch. The problem with that setup is that people tend to switch it off when the engine is running!
So, I know I need to run new cabling to the VSR - with runs now shorter than previously (max about 1 metre) what is the minimum cable grade I should use? I intend to get the local auto electrician to make them up.
Also, I will need to pull 12v from the battery up to the switch panel...what is the best arrangement to tap onto the battery? I was thinking about bringing cabling up to a Positive bus bar and from there taking feeds into the switch panels. Again, any suggestions of nice ways to do that?

I gather that the BM2 requires no other cabling off the house battery's neg terminal. I currently have the Eber neg on that and also the main neg for the domestics. I want to keep the Eber on the that battery (to preserve the starter just in case it runs it down), where to I get my neg from for those?

What grade cable is recommended for general domestic cabling? Is 15/16 awg OK for short runs (<1metre) with nominal load eg for nav lights, radio etc).

Finally (for the moment), I intend to use 3 battery isolator switches (701's)to be able to separate the supplies, for those with similar set ups, do you use bars to join these together or cables?

Many thanks in anticipation for helpful guidance. Oh and yes I do have good reference material, I am looking for some practical suggestions and ideally some nice photos/illustrations to make real what I have in my head.
Cheers

 

[pmagowan]

Do you not have a neg buzz bar at your switch panel. The starter should not run down with a VSR attached as it will disconnect from the house at a set level. There will be someone along shortly with all the knowledge. I redid all of mine the same as you, with a VSR and a BEP battery monitor but I can't remember what size cables etc except that there are tables online that let you calculate them based on voltage drop. I simply went one bigger after consulting others on here.

 

[Pladdatoo]

Do you not have a neg buzz bar at your switch panel. The starter should not run down with a VSR attached as it will disconnect from the house at a set level. There will be someone along shortly with all the knowledge. I redid all of mine the same as you, with a VSR and a BEP battery monitor but I can't remember what size cables etc except that there are tables online that let you calculate them based on voltage drop. I simply went one bigger after consulting others on here.

I am currently adorned with multitudes of chocblocs which "serve" as bus bars. These are to be replaced with proper ones.
I was wondering how to tap off for the neg bus bar?

 

[nickd]

Would recommend Furneaux Riddell
http://www.furneauxriddall.com/acatalog/Key_Operated_Battery_Isolators.html
I used three key operated isolators
One for starter
One for domestic
One to join Starter and Domestic together
The third does not have a key in it, this prevents the accident of a guest joining the two together and flatting everything.
FR do tinned cable, bus bars everything - all of the cable has current on it so size appropriately

 

[pmagowan]

I used this company http://www.power-store.com/?id=10

They have lots of useful information on their website and seem to have most of the bits I needed.

 

[Spirit of Glenans]

Am undertaking a bit of a re-wire, so have a few questions to ask. I am looking for some best practice advise, so please be patient, I am keen to learn and do it well and don't want to just hand it over to an expert and not become intimate with my boats electrics.

Apart from replacing old wiring (some of which appears to be domestic household 3-core)
Cheers

There's a lot to be said for domestic 2.5sq.mm. T&E. With that kind of cross-section you get very little current drop over long runs, and the covering is quite robust. My previous boat which I sold two years ago was originally wired with this in 1984 and it was still fine.

 

[oldsaltoz]

Some of the lessons I have learned include.
Make sure you know what each wire goes to and comes from, then label them.
Also note the power requirements of each item and note them.
Do a wiring diagram and keep a copy on board.
Spray all printed circuit boards with a good quality protective coating made for just this purpose.
The square conduit with a removable cover strip not only protects your wiring but also gives you easy access.
Calculate the maximum for each breaker or fuse and add 20%.
Cabin lights should be on more than one breaker/fuse, so that if one drops out you still have some lights available below deck.
Similarly, do not put navigation lights on the same breaker/fuse as mast head or deck lights, you might to light her up and you don't want a single fuse/breaker to take out all illumination.
Bulge pumps should not all be on one breaker/fuse for obvious reasons.
Only join wires with the heat shrink that has an epoxy coating inside it, made for wet environments.
use tinned wire (best practice) where possible.
If you have space, build in a live current test lamp with a probe.
Use a positive and negative bus bar system.
Breakers are the way to go, try changing a fiddly fuse in the dark on a stormy night if you need convincing.
Look for a low battery voltage alarm that has a timer to turn itself off after a pre set time, gages help but who looks at them. and how often.

There is a hand book called the 12 volt hand book available on the net, but I seem to have lost the link, hopefully someone will read this and post the address.

Good luck and fair winds.

 

[RobBrown]

http://www.smer.fi/docut/12volthandbook.pdf

 

[TQA]

Some of the lessons I have learned include.
Make sure you know what each wire goes to and comes from, then label them.
Also note the power requirements of each item and note them.
Do a wiring diagram and keep a copy on board.
Spray all printed circuit boards with a good quality protective coating made for just this purpose.
The square conduit with a removable cover strip not only protects your wiring but also gives you easy access.
Calculate the maximum for each breaker or fuse and add 20%.
Cabin lights should be on more than one breaker/fuse, so that if one drops out you still have some lights available below deck.
Similarly, do not put navigation lights on the same breaker/fuse as mast head or deck lights, you might to light her up and you don't want a single fuse/breaker to take out all illumination.
Bulge pumps should not all be on one breaker/fuse for obvious reasons.
Only join wires with the heat shrink that has an epoxy coating inside it, made for wet environments.
use tinned wire (best practice) where possible.
If you have space, build in a live current test lamp with a probe.
Use a positive and negative bus bar system.
Breakers are the way to go, try changing a fiddly fuse in the dark on a stormy night if you need convincing.
Look for a low battery voltage alarm that has a timer to turn itself off after a pre set time, gages help but who looks at them. and how often.

There is a hand book called the 12 volt habd book available on the net, but I seem to have lost the link, hopefully someone will read this and post the address.

Good luck and fair winds.

Good luck anf fair winds.

+ 1 on the above ESPECIALLY ON THE USE OF TINNED WIRE.

 

[dazautomatics]

Hi Pladdtoo

First of all, don't waist your money on a Nasa or any other type of battery monitor, ( I have one of these and have fitted other types as well) you can fit a quality voltmeter and this will give you the same information if it is used with the voltage charts that can be found on the internet detailing the state of discharge from the rested battery voltage, look for a chart relevant to your type of battery. All the battery monitors do is leave a big hole in your bulkhead and stress you out! If you do want to monitor what you are using then get an ammeter (Same set-up as BM-2) if you are using solar or wind charging then you could fit 2 (1 in and 1 out) better than BM-2, the 12 volt handbook will show you how. Both analogue meters can be found through Blue sea systems at a high price or from other places on the internet at a much reduced price.

Tinned cable is very good but expensive, so unless you have a very wet boat I wouldn't waste your money. It rotts just the same when exposed to salt water, I would recommend the use of "Thin walled cable" which can be found from this company (http://www.autoelectricsupplies.co.uk/product/70/category/114) at a very reasonable cost and you can also purchase per meter as well as the reel. The thin walled cable uses a new technology that has been adopted by the automotive industry and also some of the marine, as it thinner, more economical and more resistant. Also they give you the cable rating in amps so you can determine what cable you need for devices, over spec cable is not a problem if you have the room. Also look out for fridges, autopilots and other devices that suffer from voltage drop and require considerably larger cable than the rating on the back of the device.

As for your other questions I would use 2 bus bars for your domestic switch panel but locate the negative bus bar away from the back of your panel, possibly in an adjacent locker to reduce the risk of a short. You can then run a large cable (whatever your consumption x 2) back to your batteries. Also if you have the room use a connection blocks behind your switch panel to terminate you cables from appliances or devices and then use 1 cable up to your switch panel, this saves you trying to connect 7 wires onto the back of the cabin light / instrument breaker.... If these are mounted to correspond with your switch panel i.e. top left connecter is the top left switch then identifying cables is so much easier. An example of a good connection block is as follows (http://www.autoelectricsupplies.co.uk/product/51/category/116) as long as this is used with the correct insulated terminal connectors, or you can use din rail connectors which can be found at electrical wholesalers.

Also I would be inclined if you are replacing most of your cables to go with a colour coded system as this makes identifying faults so much easier, especially used with the above connection block system negates the use of wiring diagrams. You can use your own colours like: Red for M&E, yellow for domestic lighting, orange for nav lights ect…… or you can go onto the internet and use one of the marine colour coded systems.

.

As for your VSR you should be able to find diagrams on the internet from the manufactures or generally run a cable from your motor + bus bar through the relay and down to your domestic batteries. I would also recommend the use Mega fuses, which as the name states is a massive fuse normally rated at 100A for domestic and 200A for the motor (Please check) and are fitted as close to your batteries as you can get them on the main supply cable. These are your last line of defence of you make a catastrophic error or supply cables short.

Anyway, good look with your wiring.

Regards Darren

P.S. Please do not use domestic 3 core cable or more to the point Brown and Blue for 12 volt cables as this is for 230vac and is a very quick way to get yourself into the Darwin awards. By touching the wrong cable end thinking that is 12 volts!!!

 

[rbmatthews]

I have just completed more-or-less the same as what you are hoping to do. Description and pictures at http://shetlandf4.wordpress.com/rewiring/.

I used tinned AWG 16 for most of the normal domestic wiring, AWG 14 for the feeds from batteries to dashboard, and AWG 8 for the VSR cables. One isolator switch for each battery.

I am working on a wiring diagram at the moment which I will post in due course, but feel free to ask any questions.

Rob.

 

[dazautomatics]

I have just completed more-or-less the same as what you are hoping to do. Description and pictures at http://shetlandf4.wordpress.com/rewiring/.

I used tinned AWG 16 for most of the normal domestic wiring, AWG 14 for the feeds from batteries to dashboard, and AWG 8 for the VSR cables. One isolator switch for each battery.

I am working on a wiring diagram at the moment which I will post in due course, but feel free to ask any questions.

Rob.

Hi Rob

Have looked at your wiring and would recommend the use of more cable ties, cable bases and "P" clips. some of your connections are far to close together. remember that you will be using your boat at planning speeds and the wires you have fitted with move about and could cause you problems or a fire. All cables should be fitted in a cable tray or secured to the vessel correctly. also try as much as possible to segregate your positive and negative cables. If you have done this since you took the pics then my sincerest apologies.

I have mentioned this before on the forum and I appears to fall on to deaf ears, that unless your wiring a vessel you intend to keep above 40 years + then again I would not be wasting your money on tinned cable. Our boat is 40years old and has some standard copper wiring in the deckhead that is not removable and this is still like new. As far as I am aware, most mainstream boat manufactures use normal copper cable. If you are fitting cable near a water source then you need to rethink your locations. It is possible to tin (Apply solider) to the end of cables in a higher risk area, this if done properly will seal the end of the cable to stop the wicking effect. (I have spent 20 years working with tinned cable commercially away from boats and it still rots very quickly) In fact last year I rewired an Avon rib for a friend and after 1 season the commercial grade tinned cable used had turned green and had started to deteriorate to the level that the rib was unreliable. With technology moving on so quickly and new equipment being fitted to your boat every year then a re-wire every 10 years or so is a good way to stop electrical fires, thus your tinned cable will probably be in the bin and replaced anyway! Sorry this is a sore point, I have seen so many boats with chock blocks dangling all over the place and bodged connections to keep the fire service going for years.

Spend your time planning your system and organising your connections so that you can find problems easy and without a wiring diagram. Remember that is a rough sea at the night, possibly close to a lee shore, Generally when things do going wrong and the boat goes black! that's when your well thought out and very tidy wiring will save you calling the big orange taxi

As you can tell I don't like wasting money, that must be the Yorkshire in me!!!!! LOL

Now I've seen yours so I thought I would be rude not so show you what I was doing for a month or so last year on a friends boat. This is just my hobby. I play with powered doors to pay for beer

 

[Pladdatoo]

Hi Rob



Now I've seen yours so I thought I would be rude not so show you what I was doing for a month or so last year on a friends boat. This is just my hobby. I play with powered doors to pay for beer

]

Ok, I'm convinced.............If you ever want to practice your hobby again, give me a shout !!

 

[dazautomatics]

Ok, I'm convinced.............If you ever want to practice your hobby again, give me a shout !!

Unless your in the West Indies then I may be a bit far away from you to help. but good luck, I'm
sure you will have a reliable system when you finish

Best Regards

Darren

 

[rbmatthews]

Now I've seen yours so I thought I would be rude not so show you what I was doing for a month or so last year on a friends boat. This is just my hobby. I play with powered doors to pay for beer

It's a work of art, Darren. I feel like ripping all mine out and starting again!

Thanks for the comments, though.

R.

 

[john_morris_uk]

There are a couple of things I would disagree over. in what has been said so far. Firstly I do believe that tinned wire is worth the extra money. I've had to play with wiring done with none-tinned on various boats and its a pain in the backside as the copper deteriorates in the salt atmosphere.

Secondly, don't worry overly much about making the battery cables less than a metre in length. I can't remember a boat where battery cables were that short; just make sure that they are the appropriate cross section of cable.

 

[oldsaltoz]

Thanks for the link Rob.
The link I had was out of date.

Good luck and fair winds.

 

[lpdsn]

...
I used three key operated isolators
One for starter
One for domestic
One to join Starter and Domestic together
The third does not have a key in it, this prevents the accident of a guest joining the two together and flatting everything.
...

An alternative would be to have the third key just connect the domestics to the starter circuit. If the engine battery is buggered no point in having it in the circuit and dragging down the other batteries.

 

[ghostlymoron]

An alternative would be to have the third key just connect the domestics to the starter circuit. If the engine battery is buggered no point in having it in the circuit and dragging down the other batteries.

I've always advocated this but have been shouted down by the majority on here. (in the nicest possible way)

 

[Pladdatoo]

riginally Posted by lpdsn View Post
An alternative would be to have the third key just connect the domestics to the starter circuit. If the engine battery is buggered no point in having it in the circuit and dragging down the other batteries.

I've always advocated this but have been shouted down by the majority on here. (in the nicest possible way)

Anybody able to sketch me out a basic circuit diagram for this arrangement, as opposed to one with the starter and domestic batteries connecting together?