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all right everyone uh welcome to another   session of a tech talk   votingtechtalk.com i'm jeff cote here at   pacific yacht systems and thanks for   tuning in we've got a question from a   fellow voter named mark   uh mark   states jeff my devices primarily viktron   have case grounds both of my inverters   have significant studs to connect to   ground should i connect these case   grounds and then wire them back to the   dc ground bus   in series   do i need to connect them to switched or   unswitched side of the dc ground switch   okay   well first of all in north america you   probably don't want to have an ice we   don't do that not to say it can't be   done but it's uncommon to have a switch   on the dc ground   so   one word that's commonly used   for   grounds is the word common   and common means it's a place that all   grounds connect to   so that would mean uh a dc ground bus   would also be connected to an ac ground   bus if they have to they can't be   separate   and then you might have a bonding ground   connected to that you might have an rf   ground connected to that you might have   a lightning ground connected to that   there's various types of grounds on a   boat but the most   let's say popular ones are an ac ground   a dc ground and   a bonding ground   you should absolutely avoid using series   connection for grounds   meaning all grounds should be hub and   spoke   if it fails you lose only one spoke you   don't want to lose two spokes right   because once you put things in series   you're saying oh i'm going to connect   one inverter to another inverter and   then i'm going to have that inverter   connect to ground   it's tempting to do that but you can't   you're going to want to have each   inverter connected   to your grounding bus   and then you're also going to want to   have both of your inverters connected to   a unswitched grounding bus meaning   there's no situation where you're going   to want to isolate a ground from an   inverter and   you don't need to have a switch to do   that   so yes and remember for boats the code   for ac grounds   and dc grounds for inverter chargers is   quite different than on land   and the rule is that the connector size   to an inverter charger for the ground   has to be   a minimum of one size smaller   than the biggest cable connected to the   device so for instance if your inverter   charger is connected with two watt   wiring which is about the size of a   finger you know maybe an index finger   something like that or a thumb   you know maybe that's maybe four ought   but you know a large cable is connected   to your inverter charger you're going to   want to make sure that the chassis   ground connection so if for instance the   connection is too odd   the chassis ground connection can only   be one size smaller so you go from two   to one now i get this ask all the time   jeff can i make it bigger absolutely you   can make it two odd all the way   but the code says it has to be only one   size smaller that's the minimum   than the largest cable both ac and dc   connected to that device so that's a   good question from mark and by the way   if you're confused about grounds welcome   to the club it took me a long time to   figure it out uh nigel calder has lots   of good info on that he's got a whole   section in his book just about grounds   and take your time digest it read it   read it over again   and it took me years to really get it it   sounds trivial to all of us all this   stuff and we are always hard on   ourselves telling ourselves that we   should figure it out by now   but with electricity it's about concepts   and it's just being gentle to yourself   and kind to yourself   about uh not understanding those things   as quickly as maybe we all would have   hoped so great question from mark and   thanks for all of you for tuning in and   safe boating so if you're curious again   go on our website and find out more   answers and solutions with this sort of   setup and thanks for asking and thanks   for all of you for listening and tuning   in