Does that set up a different ground potential when connected to shore power (AC side and 12V side)?
Neil Andersen Rock Hall, MD 21661 ________________________________ From: Dave S <syerd...@gmail.com> Sent: Saturday, May 30, 2020 9:41:36 AM To: Neil Andersen <neil.eric.ander...@gmail.com> Cc: Brian Davis <brianwdavis...@gmail.com>; cnc-list@cnc-list.com <cnc-list@cnc-list.com> Subject: Re: Stus-List Grounding 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<mailto: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<mailto:cnc-list-boun...@cnc-list.com>> on behalf of Dave S via CnC-List <cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>> Sent: Saturday, May 30, 2020 9:18:24 AM To: Brian Davis <brianwdavis...@gmail.com<mailto:brianwdavis...@gmail.com>>; C&c Stus List <cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>> Cc: Dave S <syerd...@gmail.com<mailto: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<mailto: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<mailto: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<mailto:brianwdavis...@gmail.com>> To: cnc-list@cnc-list.com<mailto: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<mailto:j...@dellabarba.com>> To: cnc-list@cnc-list.com<mailto: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<mailto: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 [https://docs.google.com/uc?export=download&id=0BxaAN3B_Cl8LYklSNlB4cFM5UWs&revid=0BxaAN3B_Cl8LVUNlN1orQTlTc05OdzFHMXV6WFM2R281S1EwPQ]
_______________________________________________ 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
