---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 07/26/18: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:42 AM - Re: Question for Bob (GusF16rv8) 2. 08:16 AM - Grounding architecture (Robert L. Nuckolls, III) 3. 12:16 PM - Re: Grounding architecture (Rocketman1988) 4. 07:13 PM - Re: Re: Grounding architecture (FLYaDIVE) 5. 07:57 PM - Re: Re: Grounding architecture (Charlie England) 6. 08:39 PM - Re: Grounding architecture (Rocketman1988) 7. 08:57 PM - Re: Re: Grounding architecture (Charlie England) ________________________________ Message 1 _____________________________________ Time: 06:42:08 AM PST US Subject: AeroElectric-List: Re: Question for Bob From: "GusF16rv8" nuckolls.bob(at)aeroelect wrote: > Do you have a wire running from battery(-) up to your firewall ground bus? > > Yes I do. My guess is that it is an 8AWG wire running from the battery to airframe ground connection forward to the ground bus. That forward ground bus is also grounded to the airframe. > > Okay . . . the resistance of that wire is probably > 100 times higher than the airframe. The wire doesn't > hurt anything but it adds no value. > > Isn't the point of having a bus or 'field of tabs' grounded directly to the negative batt terminal to prevent ground loops through the airframe? If so, why then is the wire of no value, because of its length due to being run from the rear? >From the explanation above, it sounds like both ends (batt neg terminal and ground bus) are also grounded to the airframe, is that correct? Could you specify which wire is 'adds no value' and how the planned system SHOULD be grounded then? Thanks! -------- Gus RV8 SlowBuild (2006-?) Read this topic online here: http://forums.matronics.com/viewtopic.php?p=481864#481864 ________________________________ Message 2 _____________________________________ Time: 08:16:05 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Grounding architecture Okay . . . the resistance of that wire is probably 100 times higher than the airframe. The wire doesn't hurt anything but it adds no value . . . Isn't the point of having a bus or 'field of tabs' grounded directly to the negative batt terminal to prevent ground loops through the airframe? If so, why then is the wire of no value, because of its length due to being run from the rear? From the explanation above, it sounds like both ends (batt neg terminal and ground bus) are also grounded to the airframe, is that correct? Could you specify which wire is 'adds no value' and how the planned system SHOULD be grounded then? Thanks! We're talking two separate issues: (1) Ground path integrity for DC power distribution and . . . (2) shared ground paths bet ween potential antagonists [alternators, strobe supplies, etc] and potential victims [audio systems, some avitonics]. This thread is about issue #1. Yes, we'd like to achieve the lowest practical path resistance between the battery(-) and the firewall ground block. For aircraft with the battery forward, taking battery(-) directly to the stud is ideal and practical. For batteries mounted aft in a metal aircraft, taking battery(-) to structure is the most practical. https://goo.gl/28exWU Now, if one were to measure the airframe resistance between the battery(-) grounding location on the airframe and the firewall ground block stud, one would measure some exceedingly small resistance . . . generally under 0.001 ohms (resistance from nose to tailcone on a Beechjet is right at .001 ohms). Enhancements to conductivity by adding some bit of wire in PARALLEL with the structure would be very difficult to measure. GROUND LOOPS are a separate discussion unique to managing grounds for potential victims and is unrelated to management of DC power. Bob . . . ________________________________ Message 3 _____________________________________ Time: 12:16:18 PM PST US Subject: AeroElectric-List: Re: Grounding architecture From: "Rocketman1988" So is running a 2 AWG cable from the aft mounted batteries on an RV 10 to a firewall stud a bad plan? Would a basic airframe ground be the better option,i.e. ground the batteries at their aft mounted location? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=481866#481866 ________________________________ Message 4 _____________________________________ Time: 07:13:47 PM PST US From: FLYaDIVE Subject: Re: AeroElectric-List: Re: Grounding architecture Nothing beats a copper wire ground on a plane. There is no reason why you can not do both... A wire from the battery to the Firewall/Ground Buss and a short Ground wire to the airframe. Barry On Thu, Jul 26, 2018 at 3:15 PM, Rocketman1988 wrote: > Rocketman@etczone.com> > > So is running a 2 AWG cable from the aft mounted batteries on an RV 10 to > a firewall stud a bad plan? Would a basic airframe ground be the better > option,i.e. ground the batteries at their aft mounted location? > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=481866#481866 > > ________________________________ Message 5 _____________________________________ Time: 07:57:56 PM PST US Subject: Re: AeroElectric-List: Re: Grounding architecture From: Charlie England On 7/26/2018 2:15 PM, Rocketman1988 wrote: > > So is running a 2 AWG cable from the aft mounted batteries on an RV 10 to a firewall stud a bad plan? Would a basic airframe ground be the better option,i.e. ground the batteries at their aft mounted location? > I think the idea is that running the extra ground wire forward is not a *bad* idea; just an unnecessary one, in a metal a/c. The airframe will be a lower resistance ground path than any practically size wire. Problems related to the ground loop issue are usually limited to audio gear. I'm sure Bob can give you a better, more precise description of what happens. But my layman's description is this: If a low level signal, like audio, shares its ground return path with much stronger, 'noisy' electrical signals, like a strobe, the strobe noise can effectively become part of the audio signal, and you get the noise in the audio system. To prevent that, you use the 'forest of tabs' located somewhere near the audio (and other low signal level) gear, and run all low level signals to that spot instead of through the airframe. That keeps the ground paths of the low level stuff & the 'noisy' stuff separate. Charlie --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 6 _____________________________________ Time: 08:39:26 PM PST US Subject: AeroElectric-List: Re: Grounding architecture From: "Rocketman1988" If running a large wire ground isn't necessary, how does Z-15 fit in? Just curious... Read this topic online here: http://forums.matronics.com/viewtopic.php?p=481873#481873 ________________________________ Message 7 _____________________________________ Time: 08:57:09 PM PST US Subject: Re: AeroElectric-List: Re: Grounding architecture From: Charlie England On 7/26/2018 10:38 PM, Rocketman1988 wrote: > > If running a large wire ground isn't necessary, how does Z-15 fit in? > > Just curious... Are you asking me? (no context for your question in the email version) If so, did you read the text (pg z-4) that's associated with the drawing? --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.