Interesting question. The term ‘ground’ probably should be distinguished from the negative side of the dc circuit. Can’t speak to more sophisticated boats but in my relatively simple 33-2 The AC system is isolated, grounded only when connected to shore power. I do not run any AC loads otherwise, no inverter. The 12v system would ultimately ‘ground’ To the water via the engine, prop and shaft.
Dave On Sat, May 30, 2020 at 9:33 AM Neil Andersen <neil.eric.ander...@gmail.com> wrote: > Where do you actually go to “ground” off the bus?? > > Neil Andersen > 1982 C&C 32 > Rock Hall, MD > ------------------------------ > *From:* CnC-List <cnc-list-boun...@cnc-list.com> on behalf of Dave S via > CnC-List <cnc-list@cnc-list.com> > *Sent:* Saturday, May 30, 2020 9:18:24 AM > *To:* Brian Davis <brianwdavis...@gmail.com>; C&c Stus List < > cnc-list@cnc-list.com> > *Cc:* Dave S <syerd...@gmail.com> > *Subject:* Re: Stus-List Grounding > > Essentially yes, however when you are thinking of the boat's wiring, I > would think of the ground bus as the centre, with the engine connected to > it, rather than the reverse. Think of it a hub or a star - with the > ground bus at the centre. (Google "star grounding") one of those paths > has to finally cross the shunt to be measured. (those loads which are > powered by the house bank) > > That green wire is the ground for the aluminum fuel tank. The rest are > batteries (house 1,2, and start) or engine, plus the shunt. All are at > the same ground potential. On the other side of the shunt is > the smartcharger, the refrigeration unit, the house breaker panel, and > anything else I want to "see" in the BMV 700. Basically anything that > impacts the house bank, (though this does not include the alternator.) > > Dave > > > > On Sat, 30 May 2020 at 08:43, Brian Davis <brianwdavis...@gmail.com> > wrote: > > Thanks, Dave. I have the same type of shunt that came with the Blue Sea > panels I'm installing and will have the same monitoring. I see in you pic > there's a green wire (grounding?) going to the bus along with the blacks > (negative batteries). So, all of that goes to the same engine connecting > point and the grounds and negatives share that single point? Just want to > make sure I completely "get it". > > Thanks for all your guys help. > > On Sat, May 30, 2020 at 8:21 AM Dave S <syerd...@gmail.com> wrote: > > Agree with Joe's comment. the engine must be grounded but should not be > used as your primary grounding point. > there are a buncha' good reasons for this. Another thing to consider is > providing for an upgrade the battery/power monitoring, for which you may > need to install a resistive shunt between the battery and the various > grounds you wish to monitor, Here's a photo of the shunt (on the > right) and ground bus (left) in my 33-2, you can see the ground bus and > various grounds attached, this bus is connected to one side of the shunt, > the other side of which is connected to the house breaker panel and the > other accessories that are measured by my battery/power consumption > monitor. This is the shunt that victron provides with the BMV-700. > > > https://3.bp.blogspot.com/-LeNHHo5kK2k/V5V0MaFJ_cI/AAAAAAAAAkc/VI_Cm3z-Aa0m_dZ9AmlgaeVdXmXQOINkgCLcB/s1600/blog%2Bgrounding%2B2.jpg > > > > Dave > > > > > > > > -- Forwarded message ---------- > From: Brian Davis <brianwdavis...@gmail.com> > To: cnc-list@cnc-list.com > Cc: > Bcc: > Date: Sat, 30 May 2020 07:32:16 -0400 > Subject: Stus-List Grounding > Hello everyone, > > Hope you quarantine projects are going well. > > I have a question about grounding. I'm currently refitting ALL wiring from > scratch on our 1980 Landfall 38. I literally gutted every piece of wire and > bought all new Ancor tinned marine cables in every guage you can imagine. > She's coming along swimmingly, and I've mapped everything out pretty well > in a 8 page layered diagram that I'm happy to email direct to anyone who > wants it. It's in PowerPoint and about 8mg. > > My question about Grounding is if it's ok to use my engine as the > grounding point? I'm using the similar area for the Negative connection for > the 3 battery banks, but a different bolt to the engine case. Several > appliances including the breaker panels, ACR, battery charger, water > heater, fuel tank, etc require a ground and I'm using a 6 awg green wire > from the engine to a large Blue Sea busbar. Then connected the grounds to > it. > > I've also run a 2awg wire from the mast step to the keel bolt and to one > of the stanchion bases from underneath for lightning protection. However I > kept that all separated and not connected to the grounding. > > Make sense? Or am I missing something? Again, happy to send my diagram for > review. > > Regards, > Brian > South FL > > > > ---------- Forwarded message ---------- > From: Joe Della Barba <j...@dellabarba.com> > To: cnc-list@cnc-list.com > Cc: > Bcc: > Date: Sat, 30 May 2020 07:52:37 -0400 > Subject: Re: Stus-List Grounding > > Don't use the engine for ship's ground. Use one of these: > > > https://www.bluesea.com/products/2127/MaxiBus_250A_BusBar_-_Four_5_16in-18_Studs > > Your AC ground bus will connect to that ground point as well. Speaking of > AC, make sure you have a galvanic isolator. > > Run ONE ground wire to the engine. You don't want your engine block to be > a routine conductor of electricity. > > Here is your lightning ground conundrum: The old way was to connect all > metal together. Coquina came with a ground wire system that connected every > single thru-hull, the mast step, the engine and the keel. The problem with > that is if the zinc does not work perfectly, you can have electrolysis on a > large scale since you have all this metal wired together. I undid all that, > no thru-hulls are wired to anything. The mast is wired to a keel bolt with > 4 gauge wire. The ship's ground bus is wired to the engine with one ground > wire. > > > Joe Coquina > On 5/30/2020 7:32 AM, Brian Davis via CnC-List wrote: > > Hello everyone, > > Hope you quarantine projects are going well. > > I have a question about grounding. I'm currently refitting ALL wiring from > scratch on our 1980 Landfall 38. I literally gutted every piece of wire and > bought all new Ancor tinned marine cables in every guage you can imagine. > She's coming along swimmingly, and I've mapped everything out pretty well > in a 8 page layered diagram that I'm happy to email direct to anyone who > wants it. It's in PowerPoint and about 8mg. > > My question about Grounding is if it's ok to use my engine as the > grounding point? I'm using the similar area for the Negative connection for > the 3 battery banks, but a different bolt to the engine case. Several > appliances including the breaker panels, ACR, battery charger, water > heater, fuel tank, etc require a ground and I'm using a 6 awg green wire > from the engine to a large Blue Sea busbar. Then connected the grounds to > it. > > I've also run a 2awg wire from the mast step to the keel bolt and to one > of the stanchion bases from underneath for lightning protection. However I > kept that all separated and not connected to the grounding. > > Make sense? Or am I missing something? Again, happy to send my diagram for > review. > > Regards, > Brian > South FL > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each and > every one is greatly appreciated. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray > > _______________________________________________ > CnC-List mailing list > CnC-List@cnc-list.com > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > > > > -- > Brian Davis > 1980 C&C Landfall 38 > "Nina" > Southeast Florida > >
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