mii11x Posted December 20, 2018 Share Posted December 20, 2018 Hi again fellas, So after tidying up all my existing switch wiring under the dash, the next step is to wire up the new sounder. I have a switch panel on the dash which I will be wiring into. Also under the dash is like a distribution block for grounding, but it also takes an input of 12v direct from the positive on the battery and input from the negative. The positive on the distribution block then wires into a 15A inline fuse then into the switch and is chained for all 4 switches on the back of the switch panel. Lowrance recommend a 5A fuse to be wired in. Am I correct with where I am wiring in the inline fuse in my crudest of diagrams below - I have drawn where I think it should go in red. I also noticed that my bilge, stern and nav lights dont have any inline fuses, should I be adding them in? Thanks Mick Link to comment Share on other sites More sharing options...
zmk1962 Posted December 20, 2018 Share Posted December 20, 2018 (edited) This is what I would be doing. At present your wiring is protected by 1x15A fuse. The fuse is holding the combined load of all the devices that the switches are controlling. So if you had the bilge on (15A) and the sounder (5A) plus the lights, you would be drawing 20A+...ie. more than 15A and more than likely the fuse would blow. Also at present, if you have a short at the distribution block... there is no protection for the wiring and it will burn from the distribution block back to the battery. Putting a fuse (25A or 30A) between the block and the battery will protect that wiring (the fuse will blow first). This fuse has to carry the combined load of everything you plan to turn on at the same time....of course this assumes your main wire from battery to the distribution block is also rated to carry the 25-30A you are projecting to support if all the devices are on and drawing their full current. Then, again assuming each switch is rated to support more than the draw load of the device it controls, you can put the fuse after the switch (otherwise before the switch and the fuse has to be at or below the switch rating). Typically the switches are rated 15A so I have drawn the fuses after the switches as all the devices you mention draw less then 15A. I'd have lights wired with a 2-5A fuse, bilge minimum 15A (but it would be stated on the device) and sounder as you have stated is 5A. Cheers Zoran Edited December 20, 2018 by zmk1962 1 1 Link to comment Share on other sites More sharing options...
zmk1962 Posted December 20, 2018 Share Posted December 20, 2018 (edited) Forgot to mention its not just about how much your devices draw or the combined load of all devices in a circuit. Fuses are used to cap the max amount of current that you want to allow to flow. So if there is a power spike, in the way your wiring is set up, the 15A fuse would let 15A through toward the switches and to the devices (if the switches were ON). This could damage the devices that can't handle 15A. Which is why the sounder manufacturer is advocating you protect the sounder with a 5A fuse in the sounder circuit... the 5A fuse will not allow more than 5A current to flow through the device before it blows and breaks the circuit. Cheers Zoran Edited December 20, 2018 by zmk1962 2 1 Link to comment Share on other sites More sharing options...
Sigma Posted December 20, 2018 Share Posted December 20, 2018 (edited) Absolutely agree with zmk1962. All equipment should have a fuse as this is what protects it in case of an overload. This is why I installed a fuse box and everything is running to that....everything has its own fuse. Cheers Dave Edited December 20, 2018 by Sigma 2 Link to comment Share on other sites More sharing options...
Fishop Posted December 21, 2018 Share Posted December 21, 2018 One day Ill get to re-wiring my boat. Might look at a fuse box to tidy it up/simplify it. 1 Link to comment Share on other sites More sharing options...
mii11x Posted December 23, 2018 Author Share Posted December 23, 2018 Cheers fellas for the responses. ZMK1962 I rewired as you mentioned on my diagram, without a fuse box though. I had some inline fuse casings in the garage that I put to use. Everything looks much neater now under the dash and all my circuits are protected with fuses. Checked everything once finished and all my lights, bilge and new sounder work fine. Link to comment Share on other sites More sharing options...
shakey55 Posted December 23, 2018 Share Posted December 23, 2018 On 12/20/2018 at 8:11 PM, mii11x said: Hi again fellas, So after tidying up all my existing switch wiring under the dash, the next step is to wire up the new sounder. I have a switch panel on the dash which I will be wiring into. Also under the dash is like a distribution block for grounding, but it also takes an input of 12v direct from the positive on the battery and input from the negative. The positive on the distribution block then wires into a 15A inline fuse then into the switch and is chained for all 4 switches on the back of the switch panel. Lowrance recommend a 5A fuse to be wired in. Am I correct with where I am wiring in the inline fuse in my crudest of diagrams below - I have drawn where I think it should go in red. I also noticed that my bilge, stern and nav lights dont have any inline fuses, should I be adding them in? Thanks Mick I may be wrong, but I’ve always been told to put the fuses close to the battery. Experts will give you the proper answer. Good luck Link to comment Share on other sites More sharing options...
zmk1962 Posted December 23, 2018 Share Posted December 23, 2018 (edited) Yes @shakey55 thats correct. You will notice @mii11x only has one positive wire (the main supply) running from the battery to the distribution block and then again that single positive wire (main supply) continues to the switch(es). I have suggested a master fuse inbetween the distribution block and the battery box - ie close to the battery as you say for that main supply. This corrected what @mii11x had previously which was unprotected wiring all the way to the switches/devices. Then at the switch that main supply wire acts pretty much like the positive terminal of the battery in a circuit. - and fuses should be between that wire and the device. I have previously explained why I have put the fuses after the switch and before the device, but they could be before each individual switch - it would have just been more intricate wiring in a tight space. Cheers Zoran PS - the alternative is to run individual positive wires from the switches back to the battery terminal or to the positive terminal of the distribution block and put a fuse on each wire back there. This would complicate the number of wires running around the boat - very few cars or boats are wired that way these days. I have ONLY run individual supply wires (both positive and negative) back to the batteries when I absolutely could not eliminate electric motor noise. This only happened with two GME radio sets which were particularly sensitive to electric motors being in the same circuit. Edited December 23, 2018 by zmk1962 2 Link to comment Share on other sites More sharing options...
mii11x Posted December 24, 2018 Author Share Posted December 24, 2018 I forgot to add that I did install a fuse between the battery and the switch panel.....felling protected now 2 Link to comment Share on other sites More sharing options...
Fishop Posted December 29, 2018 Share Posted December 29, 2018 On 12/24/2018 at 6:40 PM, mii11x said: I forgot to add that I did install a fuse between the battery and the switch panel.....felling protected now What sot of fuse did you put in here? Was it an inline fuse or a fuse on the battery terminal? Also curious, do people fuse their positive cable running to the starter motor on the engine and if so, what size is required? 1 Link to comment Share on other sites More sharing options...
mii11x Posted December 30, 2018 Author Share Posted December 30, 2018 It was an inline fuse Link to comment Share on other sites More sharing options...
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