I'm curious why the engine shouldn't be used as the grounding point? Mine isn't, but only because I wanted a central ground bus in the electrical space.
In the rewire of our 35-2 that I just did, I built a ground busbar from 5/16" aluminum, installed two 5/16" main ground bolts, and 4 smaller ground screws, and installed this on one side of the electrical compartment above the engine. On the other side is a BlueSea positive busbar, fed by a BlueSea A-B battery switch. The ground bus is connected to my 100A current shunt for the battery meter with a 1/4" aluminum bar. All house loads are grounded to the busbar before the shunt. The batteries, windlass and engine starter motor are grounded after the shunt. The windlass and stern zinc anode (hung off transom) are grounded to the starboard engine mount (cable not long enough), and there is a 2/0 cable from the engine to the battery and starter grounding point at the shunt. Also, I have BlueSea on/off switch for the engine power (fed from the A/B swtich), as I don't like having my alternator and starter cables live all the time. Very easy to drop something that could short these terminals. -- Shawn Wright shawngwri...@gmail.com S/V Callisto, 1974 C&C 35 https://www.facebook.com/SVCallisto On Sat, May 30, 2020 at 5:22 AM Dave S via CnC-List <cnc-list@cnc-list.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 > > > _______________________________________________ > > 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 > >
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