biggest_kid Posted October 9, 2017 Share Posted October 9, 2017 Hey guys, I recently purchased my first boat, and am having an absolute ball with it. It is a 4.3m Seajay Nomad, with a bench seat at the back, cast deck up the front and false floor in the middle. However the previous owner left it out in the sun and weather for years, and so certain components are sun faded and just complete eyesores. This includes the switch panel, fuel lines and just about anything else made of plastic. So my plan is to replace the switch panel, and completely overhaul all the wiring for the boat in the process as it is quite messy and is setting off my OCD. Also, who knows how corroded the wiring is. I have always had an interest in electronics, and so want to DIY this job in order to learn. I have no experience in the field though, so will need some assistance please. I have already purchased a 6 gang, fused switch panel from Road Tech Marine, this one to be exact. It is pre-wired and includes a volt-meter for the battery. I am going to purchase an additional 4 gang fused panel to mount beside it as I plan on fitting more than 6 accessories. The fuses are rated for 15A and I figured this should be plenty? I have drawn up a rough diagram (attached) of where all my accessories will be placed, some of which are already in place from the previous owner. So my questions to you guys, the experts: 1) In order to connect the accessories to the switches, is all I need to do just run the positive wire (red) of the accessory to the free terminal (shown in my second attached image) on the back of each switch? If so what is that connector called? Is it a spade crimp or something like that? 2) What about the negative (black) wires of each accessory? Do they just connect to the single black wire on the back of the switch panel? 3) As I understand it, the blue is the positive for the led back light of the switches, the yellow is the negative for the led back lights and the single black wire is the negative for everything? Is this correct? 4) After connecting each accessory to the switch panel, then do I just run the positive (red and blue) and negative (black and yellow) wires of the panel to their respective terminals on the battery? 5) After some research on other forums, it was suggested to run all positives coming from the back of the panel into one heavy gauge positive wire (5-8mm in thickness) and run that back to the battery, to reduce voltage drop and also to make things neater at the battery end of the boat. Is this necessary seeing as the switch panel will only be about 1m away from the battery? Can this be done before the switch panel, or will that essentially cause every accessory to be controlled by one switch? 6) What gauge wire should I use for the accessories? Or will they already have their own wires connected to their internals, meaning that I have no choice? Is this even an issue? 7) What is the best way to connect wires for optimum conductivity and the least exposure to corrosion? Someone suggested soldering and then heat shrink tape? 8) The fuses are all in rather close proximity, if one of them blows, will it wreck the rest of them? 9) Anything else I may have overlooked that I need to know? Ratings of crimps, ratings of solder wire, etc etc? So as you can see I am a total newbie at this sort of stuff so any help you can offer is appreciated. I apologize if any of my questions are stupid, but electrics are not something I want to take any chances on. Cheers Link to comment Share on other sites More sharing options...
rickmarlin62 Posted October 9, 2017 Share Posted October 9, 2017 my first suggestion is buy tinned wire to reduce chance of corrosion...rick Link to comment Share on other sites More sharing options...
rozza_b Posted October 18, 2017 Share Posted October 18, 2017 (edited) bucket load of questions there so will answer what i can. 1. would need to see a wiring diagram of that switch panel to answer that but you should only need to connect positive to 1 point as they are all linked by the looks of it and yes they are spade connectors 2. cant tell from that picture but all my negatives run back to 1 point and then i run 1 wire back to the battery 3. need a wiring diagram to answer that but my guess would be your are on the right lines 4 & 5. run 1 wire for positive and negative to the battery no need to have a million connections at the battery that would be a nightmare to fault find if something went wrong....as for the size of the cable, you would need to calculate the total load draw by all the accessories if they where all turned on at once, 2.5mm is rated for 20amps which would probably cover everything in most tinnys i cant imagine any tinny needing 8mm cable for accessories and as rick mentioned get good quality tinned cable 6. broad question and depends on each accessory but i imagine 1/1.5mm would suit most stuff in the boat, 2.5mm max 7. would use crimped terminals on all and heat shrink the back of each crimp to prevent salt getting in, you could also use a electrical connections gel on each joint if you are worried 8. dont be worried by there closeness they are designed that way 9. get a decent quality set of crimpers and use good quality lugs cheap stuff just doesn't cut the mustard Any more questions shoot me a pm and ill help where i can Edited October 18, 2017 by rozza_b incomplete post Link to comment Share on other sites More sharing options...
Fab1 Posted October 18, 2017 Share Posted October 18, 2017 This might help you mate. 1 Link to comment Share on other sites More sharing options...
biggest_kid Posted October 20, 2017 Author Share Posted October 20, 2017 (edited) Thanks Rozza for all the help, appreciate it mate. Quick question though: where can I buy good quality tinned cable? And what are good quality lugs? In fact where can I buy all the stuff I will need? I'll need tinned wire, spade connectors, butt crimps/connectors for joining 2 wires together, heat shrink, a crimping tool/ratchet Thanks for the thread Fab, helped me to nut out exactly how to do this. Edited October 20, 2017 by biggest_kid Link to comment Share on other sites More sharing options...
rozza_b Posted October 21, 2017 Share Posted October 21, 2017 Hey mate, No worries, i would go to a electrical wholesaler to buy crimps and cable (dont go to bunnings or jaycar to buy lugs, personally think there lugs are terrible), get your heat shrink from wherever you want and as for the crimpers, try find some decent ratchet ones for that type of lug or possibly burrow some off someone, know my set that i use for work where around $250 but they are really good quality. Take your time doing it and keep it all tidy and youll come out with a good job plus if you keep it all neat and something doesnt work it will make it a million times easier to fault find, let me know if you have any more questions Rozza Link to comment Share on other sites More sharing options...
biggest_kid Posted October 24, 2017 Author Share Posted October 24, 2017 Someone said to replace the fuses that come pre-wired with the switch panel as 15A is too high and wont properly protect the circuit? Is this true? Also I was going to run an 6 or 8mm positive wire from the battery to the switch panel, and then 2 or 3mm positive wires from each switch to each device. Would this be suitable for the sort of currents I would be expecting? Then for the negative do I run another 8mm wire from the panel back to the battery, which the 2 or 3mm negative wire from each accessory splice into? Or do I run the 8mm negative from the front of the boat back to the battery, which each negative wire splices into? Bit confused here. Link to comment Share on other sites More sharing options...
Sigma Posted October 24, 2017 Share Posted October 24, 2017 (edited) PM sent... Edited October 24, 2017 by Sigma Link to comment Share on other sites More sharing options...
rozza_b Posted October 25, 2017 Share Posted October 25, 2017 21 hours ago, biggest_kid said: Someone said to replace the fuses that come pre-wired with the switch panel as 15A is too high and wont properly protect the circuit? Is this true? Also I was going to run an 6 or 8mm positive wire from the battery to the switch panel, and then 2 or 3mm positive wires from each switch to each device. Would this be suitable for the sort of currents I would be expecting? Then for the negative do I run another 8mm wire from the panel back to the battery, which the 2 or 3mm negative wire from each accessory splice into? Or do I run the 8mm negative from the front of the boat back to the battery, which each negative wire splices into? Bit confused here. Sure change them down to the fuses to sizes to suit the piece of equipment being switched will suit them better, maybe put a in line fuse on the supply cable if your that worried. Why the need for such excessive sizes of cabling ?? 6-8mm is good for over 40A i mean sure pay for it and run it and try deal with it if you must it wont hurt but its way way way to excessive. As for the negative, if your going to run 1 negative, run it to 1 point and then run all the negative cables from the accessories back to that point, dont bother splicing thats just way to much work and way to many chances for bad joints etc. Once again why then need for such excessive sizes of cabling.....run the same size cable as you do for the active, or just get the cable as a twin pair saves running 2 cables. Rozza Link to comment Share on other sites More sharing options...
rozza_b Posted October 25, 2017 Share Posted October 25, 2017 heres a chart that shows some cable sizing, use it for a guide if you want, you will notice the cabling sizes are way smaller then what your looking at, just my 2 cents cable-table-web.pdfcable-table-web.pdf Link to comment Share on other sites More sharing options...
Fab1 Posted October 25, 2017 Share Posted October 25, 2017 You could re-wire the Queen Mary with 8mm cable.4mm wire from battery + & - to the switch panel is plenty.2mm from the switch panel to your accessories is ample too. I have my nav,bildge,strip lights,sounder all running like this from a single battery no worries at all. Link to comment Share on other sites More sharing options...
Sigma Posted October 25, 2017 Share Posted October 25, 2017 You should wire your devices with whatever the device cable diamater is. For example if your device is using 2mm cable, wire the device to the panel with 2mm cable. Link to comment Share on other sites More sharing options...
antonywardle Posted October 25, 2017 Share Posted October 25, 2017 One thing to consider is the wire that goes from your battery to the switch panel.It needs to be thick enough to be able to carry all of the current that your devices will draw. I'm guessing this is why people were talking about the 8mm stuff. Add up all of the AMP's your devices are rated for and then look for the correct wire, and have a fuse that is rated correctly. 8mm is good for up to 200AMP's which is probably going to be about 10 times more than you'll need on your tinny. A lowrance elite 4 draws 1.1 amps 1 500GPH bilge pump draws 2 amps so you want two because of the live bait tank so 4AMPs Nav lights, maybe 1 AMP for each one so 3AMP That adds up to 8.1 AMPs. 2MM wire should be good for 20 AMPS, so if you put a 15AMP fuse in the middle then it will pop before the wire melts, and you've got spare capacity for when you want to add a disco ball and a jukebox! You should check that the wire size can carry the load you'll put through it. Google is your friend. good luck! Link to comment Share on other sites More sharing options...
biggest_kid Posted October 26, 2017 Author Share Posted October 26, 2017 Yeah I now realize I am being a bit excessive with cable gauges, so will tone it down a bit to save costs. Think I will do as Fab suggested, 4mm for the active wires from the battery to the panel, and 2mm from the accessories to the panel (however if an accessory has a heavier gauge, I will match that). Rozza what do you mean about running the negative to one point, and then all negatives from the accessories back to that point? I was just going to run twin-core tinned wire from each accessory back to the panel. Plug the positives onto the prongs on the back of the switches, merge all the negatives into one 4mm wire, merge the positives into one 4mm wire, and run those two 4mm wires back to the battery? Antony I won't be running a single fuse, but rather there is already 3 fuses in place that are pre-wired into the switch panel. So each 15A fuse is essentially protecting 2 switches. So as I understand it, that means one single switch would need to pull more than 7.5A to set off the fuse right? If that is the case, pulling 6A could damage sensitive electronics without actually blowing a fuse, leaving me oblivious to the problem. Have I understood this correctly? Still not sure if I have my head around this fuse situation, and I would think that would probably be the most important part of this whole process to understand correctly. Link to comment Share on other sites More sharing options...
Sigma Posted October 26, 2017 Share Posted October 26, 2017 (edited) On 26/10/2017 at 2:28 PM, biggest_kid said: Yeah I now realize I am being a bit excessive with cable gauges, so will tone it down a bit to save costs. Think I will do as Fab suggested, 4mm for the active wires from the battery to the panel, and 2mm from the accessories to the panel (however if an accessory has a heavier gauge, I will match that). Rozza what do you mean about running the negative to one point, and then all negatives from the accessories back to that point? I was just going to run twin-core tinned wire from each accessory back to the panel. Plug the positives onto the prongs on the back of the switches, merge all the negatives into one 4mm wire, merge the positives into one 4mm wire, and run those two 4mm wires back to the battery? Antony I won't be running a single fuse, but rather there is already 3 fuses in place that are pre-wired into the switch panel. So each 15A fuse is essentially protecting 2 switches. So as I understand it, that means one single switch would need to pull more than 7.5A to set off the fuse right? If that is the case, pulling 6A could damage sensitive electronics without actually blowing a fuse, leaving me oblivious to the problem. Have I understood this correctly? Still not sure if I have my head around this fuse situation, and I would think that would probably be the most important part of this whole process to understand correctly. Hey mate, I have sent you a PM but just to let you know, once you connect all the positive to the prongs, then you are left with 3 wires from the panel that need to go back to the battery. Using a bus bar to connect these near the panel and then running one single heavier gauge positive wire back to the battery would solve your problem. Same thing for the black negatives. Run the blacks from the devices and from the back of the panel to one central point and connect them to another separate bus bar (one bus bar for positive and one separate for negative conbections) then run one heavier gauge (4mm if you wish) to the battery. This will give you one earth/negative and one positive wire at the battery....much neater. Cheers Dave Edited October 27, 2017 by Sigma Link to comment Share on other sites More sharing options...
rozza_b Posted October 27, 2017 Share Posted October 27, 2017 Following on from what sigma has said, if you use a single bus for positive and a single bus for negative you can run all your required connections to that point, not only is it neater it also provides you with the abiltiy to expand or shrink the amount of connections you have at once (make the bus bigger then needed when making your initial one up) and also makes it a million times easier to trouble shoot issues. In regards to your fuses, your almost right, if a 15A fuse is protecting 2 switches the total current drawn by 1 or both switches to blow the fuse would need to be greater then 15A before the fuse blows this means that 1 switch has the potential to cause a problem, personally i would calculate the total current required by both the switches and change out the fuse to the size required. As for a single in line fuse in the supply why not do it, you can buy cheap in line fuses setups and put a fuse in right after your battery connection to protect you supply cable and everything downstream. Link to comment Share on other sites More sharing options...
biggest_kid Posted October 28, 2017 Author Share Posted October 28, 2017 Ahh bus bars, so that is how you connect all the wires? I was thinking you would somehow have to splice them all together, but had no idea how to actually do this. One thing though, my boat is an aluminium dingy with side gunwales. I was thinking of running some waterproofed (and possibly fibreglassed) 6mm ply from underneath the gunny to the floor, cutting a hole in it and mounting the switch panel to that. I would then make up a small box also out of the 6mm ply, fibreglass and waterproof it then to act as a waterproof box for all the wiring to sit inside. This would probably be a pretty tight fit depending on the size of the box, so is there any danger if the 2 bus bars come into contact with each other? That sounds like a recipe for disaster to me, but I'm not sure. Thanks for all the help by the way guys, finally starting to get my head around this process and will look at starting to purchase all the required wiring and crimps and what not soon. Link to comment Share on other sites More sharing options...
rozza_b Posted November 14, 2017 Share Posted November 14, 2017 Hey mate, In regards to busbars etc if I was doing it the way you are planning to I would make my bus bars out of terminals mounted to din rail with connector strip all in a waterproof junction box of suitable size, and then just mount that, no need to make a junction box, that's just my opinion though, busbars will work as well, just make sure you screw them down and all will be sweet. You might even be able to make up some sort of bracket so you can mount your terminal box in the piece of ply so it can be accessed from the front, oh also run all your cables into the bottom of the panel, makes it harder for water to get in the way Link to comment Share on other sites More sharing options...
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