Bilge Pump wiring/switch

I am in the process of rewiring the boat. My plan for the bilge pumps, since they are so close to the battery switch, is to attach the positive lead, through a fuse, to the bilge pump, ~ 3 ft. then run the ground wire to the dash panel switch, and then to the ground buss at the console. Since any overload situation would/could fuse to blow, I figured the shortest distance of wiring for positive would be the best. Batteries and fuse block are tucked away in the transom compartment high and dry. Anyone see anything wrong here or any other suggestions? Thanks.

Re: Bilge Pump wiring/switch

Basic wiring 101. Never put a switch, circuit breaker or a fuse in a ground wire. Period! You are just as close to the battery with the ground wire. Connect it at the battery and run the HOT wire to the switch. Since there is obviously +12V present at the console already, pick up 12V there. Why on earth would someone install a fuse panel at the back of the boat which means for every fused circuit there is another wire to run to the console.

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Can you elaborate on the wiring 101. I understand not putting a breaker or fuse in a ground ckt, but I would like to hear more about not switching a ckt on or off on the ground side.

Re: Bilge Pump wiring/switch

Perhaps electrolysis. You will probably eat up your zincs or worse.

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Bilge pumps are an important safety feature of your boat. Besides the manual dash mounted switch, the pump should also be connected to a float type switch in the bilge next to the pump. The +12VDC source for the bilge pump( + feed for dash switch and float switch) should be wired directly to the battery ( with the appropriate sized wire and inline fuse within inches of the battery to protect the wiring). The negative should go directly to the battery ground terminal. The un-iterrupted positive should feed both the float switch and the dash mounted bilge switch. Note that these two switches get wired in parallel, not series ( the dash switch should NOT have to be on for the float switch to work). As stated earlier, the ground or negative wire gets connected directly to the battery.<br /><br />There should NEVER be a switch or fuse inline with any negative power lead. Wiring 101 states that if power is off to any device, the positive(or hot) MUST NOT have any voltage. If you work with higher voltage systems, you will learn real quick how important this is to your safety.

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Can you show me where I can confirm this information pertaining to 12 volt systems.<br /><br />The reason I'm questioning is because I know of several instances where the ground ckt is used for switching, and they are all engineer designs and used by the consumer market. These ckts range from milliamp to 30amp + ckts.

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You are correct that most electronic devices switch the ground or the negative side of a circuit whether it be a radio, TV, VCR, electronic motor control, your furnace controls, etc. I'll bet good money the control devices you mention in their final application do not switch ground. If they do, that device is called a service disconnect and both sides of the circuit will be switched. However, those are self-contained control circuits which you do not have in this case. You are working with a potentially high current electrical device. There is a difference. Besides, a short to ground in the run of wire to the console on your boat would turn the bilge pump on, running it dry, and potentially creating an overheat and fire hazard. Wired properly, a short in the +12V lead to the switch would pop the fuse or breaker. Bye!

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Wow, Waterone1, I just can't believe how badly my boat's been wired. I have a Rulemate that's wired to a DTDT dash switch; the manual side of dash switch is conventional (batt switch on, dash switch on, pump runs). The AUTO side of the switch is hot wired to batt #1 and the pump is in auto mode when the dash switch is AUTO. When the boat comes off the trailer (not all boats sit in slips/moorings), the switch goes to AUTO and stays there until the beast again hits the trailer.<br /><br />Reasoning? I wanted to be able to completely disconnect all electrical power while at the dock, and still maintain an auto bilge pump. Everything is properly fused and works as advertised. Guess I didn't realize how many absolutes there are with boat wiring.

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The reasoning behind my original question was; if a short occurs in a hot (red) wire, the fuse will blow, or burn up the wiring between the short and the + side of the battery. By minimizing the length of run of the + wire, I reduce the "short" possibility. I realize there will be some, even marginal at best, voltage drop over 20 to 22 ft of wire, regardless of + or - lead. My concern was, why chance burning up a + wire 22' long when a chafe in a ground wire run that length would not cause a short. Also, let me clarify my original post. I still have my fuse block at the console. I am adding a fuse block (2 fuses)from my common on the Battery Selector Switch on the transom to power my 2 bilge pumps separtely. Each would then have their own separate ground lead to a switch on the console, then to the ground buss. I see a similar type of arrangement on my Yamaha outboard 175. The lead to power the remote oil tank pump is hot with key on. The Oil control Unit controls the pump operation by grounding and causing the pump to turn on. The indicator lights on the tach for the oil unit are also controlled this way. 1 hot wire splits to 3; green, yellow, and red. The Oil control Unit then grounds out the appropriate light for indication. I figured, if it works for Yamaha, then why not my bilge pump. If there is going to be a "chance" of a short, why not reduce the length of hot wiring. If a ground wire chafes, I doubt it would complete the circuit back to the battery on a f/g boat.<br />These are just my thoughts and nothing set in stone yet. Plan to wire up the engine and starting circuits this weekend.

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You seem to be convinced this is not a problem but I assure you, the poor SOB that has to work on this boat should it ever develop an electrical problem (or the next owner) will wonder what the owner was smoking when that wiring was added. Since you already have +12V at the console, and you also have a fuse panel at the console, and you apparently have a switch at the console, you only need one wire (+12V) going to the float switch or the bilge pump from the switch on the console. Ground the pump at the battery and go. Everything is nice & tidy. The temp horn on my boat is also activated by a ground at the temp sensor. However that lead is not fused nor is there a need for it. If it shorts the horn goes off -- provided the ignition switch is on. But then I want to know that anyway. If the + lead shorts the fuse blows. No harm - no foul. You also worry about wire length. Well, in your case current must get from the battery to the console (its already there by the main feed) as well as back to the battery so instead of a +12 run you are making the same run with a ground wire. Where's the savings? My Alumacraft livewell and bilge pumps are wired as I've suggest yours should be. Will your scheme work? Certainly -- its the logic that I'm questioning.

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Thanks for the viewoint upinsmoke. This is what I really appreciate on here. Being an ex- coastie, safety is a main concern for me. I was trying to figure how to wire the bilge pumps completey separate from main wiring harness, in case of some hidden gremlin shutting down my main supply leads. At least, I would still have pumps on a completely separate circuit. I agree, to the next guy, he would think I was a bit off my rocker wiring a switch to ground rather than to hot. I guess in order to keep uniformity on the boat, perhaps an additional hot lead to the console for the pumps will be the way to go in order to have redundency.

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It's not even so much about safety as it is about uniformity (and wouldn't it be horrible if we all thought alike). I question running a separate hot lead as well. The main feed to your console fuse panel is via a heavy gauge wire (hopefully) and is fused at the battery so why duplicate that run which would then result in running two wires. If you have an electrical gremlin it can affect any wire in the boat. Therefore you are not decreasing the chances of a problem but rather increasing them by adding two wires instead of one. More wires does not necessarily make an installation more safe or reliable. If you have a problem with the pump(s) on the water, you can use a short jumper wire to run from the battery to the pump if necessary. I carry a small spool of wire for just such emergencies and have never had to use it. Cheers.

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There are several instances of switched ground in the Automotive world. A/C compressors, even cooling fan relays are powered and switched on by a ground in some systems. I see no problem with swicthing a ground in 12volts systems.

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Again -- it works, but new boats are not wired that way and the poor service tech that has to figure out the wiring goes nuts in the process. The new owner pays the price for extra labor figuring things out. The discussion is not about engine related electrical systems. These are generally computer controlled circuits and in the electronics world switching ground is done on a regular basis. It is not done on a regular basis in vehicle power systems.

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Originally posted by Reel Poor:<br /><br />The reason I'm questioning is because I know of several instances where the ground ckt is used for switching, and they are all engineer designs and used by the consumer market. These ckts range from milliamp to 30amp + ckts. [/QB]

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Reel Poor, I like to see that. Give us an example will ya. <br /><br />Because ALL electronic equipments designed for general use are based on ELECTRON THEORY, Which states, in short, electrons flow from negative to positive. Due to this, outer casing and all metal parts of such devices serve as negative or ground. Under no circumstances a fuse shall be placed on the negative conductor for the fact that more than often the casing or metal parts will be in contact with other grounded objects such as the car chasis or water inside the boat allowing many paths for current to travel to your equipment. The negative or ground wire is there to insure the path is never interupted and will not limit current flow or prevent your equipment from functioning. Because the purpose for a fuse is to limit current flow, in this case it is useless. Fusing the negative conductor does not serve the purpose of protecting the equipments or personel. Fusing or switching should be done on the positive conductor.<br /><br />Furthermore.......

Re: Bilge Pump wiring/switch

Originally posted by recess:<br /> I was trying to figure how to wire the bilge pumps completey separate from main wiring harness, in case of some hidden gremlin shutting down my main supply leads. At least, I would still have pumps on a completely separate circuit.

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Well, you are not alone in your thinking. Folks that are serious about keeping their boats afloat pretty much blow off all conventional wiring standards and may install a bilge pump directly to the battery WITHOUT any fuse or circuit breaker. You might want to take a look at this:<br /><br /> http://www.yachtsurvey.com/bilge_pumps.htm

Re: Bilge Pump wiring/switch

i gotta scan in the page from the april seaworthy tonight<br /><br />It goes through this whole issue and the problems it causes buy hooking it in a non-standard way like galvinac reactions <br /><br />tommays<br />

Re: Bilge Pump wiring/switch

Originally posted by --GQ--:<br /><br />Reel Poor, I like to see that. Give us an example will ya. <br /><br />

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First let me say, I never said that the ground ckt should or could be fused.<br /><br />I said, I know of examples of switching in ground ckts.<br /><br />The ckts I'm illuding to are all 12 volt or less systems.<br /><br />One example is in the fuel injection system on engines. The injectors are fed a constant voltage supply and switched on and off via the electronic control module.<br /><br />Second example is on many automotive A/C and heater blower motor controls systems where the blower is fed a constant voltage and control speeds are controled via a switch and resistor set up on the ground side.<br /><br />Many automotive systems are controled via ground switching, although it is typical that many of these switches serve as ground contacts for relay coils, then the relay load contacts supply the voltage to individual componants, never the less, it's still ground ckt switching.<br /><br />All of the examples suply voltage through a wound coil before entering the switch to ground.<br /><br />And as upinsmoke said earlier most are switched on both sides.<br /><br />I'm not trying to say that its ok to wire things on a boat, house or whatever else you may question/throwout with switches in the ground ckt. Just making a general statement based on experiance. Also I'm not an electrician, nor had I ever heard of wiring 101, and was wanting some clearification for my own knoweledge.<br /><br />Now I'm really confused. Why do these examples stray from the rules.

Re: Bilge Pump wiring/switch

Originally posted by Reel Poor:<br />

Originally posted by --GQ--:<br /><br />Reel Poor, I like to see that. Give us an example will ya. <br /><br />

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First let me say, I never said that the ground ckt should or could be fused.<br /><br />I said, I know of examples of switching in ground ckts.<br /><br />The ckts I'm illuding to are all 12 volt or less systems.<br /><br />One example is in the fuel injection system on engines. The injectors are fed a constant voltage supply and switched on and off via the electronic control module.<br /><br />Second example is on many automotive A/C and heater blower motor controls systems where the blower is fed a constant voltage and control speeds are controled via a switch and resistor set up on the ground side.<br /><br />Many automotive systems are controled via ground switching, although it is typical that many of these switches serve as ground contacts for relay coils, then the relay load contacts supply the voltage to individual componants, never the less, it's still ground ckt switching.<br /><br />All of the examples suply voltage through a wound coil before entering the switch to ground.<br /><br />And as upinsmoke said earlier most are switched on both sides.<br /><br />I'm not trying to say that its ok to wire things on a boat, house or whatever else you may question/throwout with switches in the ground ckt. Just making a general statement based on experiance. Also I'm not an electrician, nor had I ever heard of wiring 101, and was wanting some clearification for my own knoweledge.<br /><br />Now I'm really confused. Why do these examples stray from the rules.

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i always subscribed to the no switch or fuse in the ground circut, but that is the way I was taught in school in the 60s , and a lot has changed since then, with these new-fangled puters and such I will keep wiring the way I have all my life, I can see how it works both ways, I just do it the way Im used to. Another thing that bothers me humpteen years ago black was ground red was hot, black tracer grounded circut red tracer hot circut to a specific device. WHAT HAPENED, did the metrics take us over on wireing also?

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Every circuit breaker on my boat is 2 poles. Except for the battery switches, every switch on the boat is 2 poles too. For everything that uses electricity, either AC or DC, both pwr and gnd (or hot and neutral if AC) are switched and ckt protected.