My Inverter Has a Case Ground, Do I Connect This to the DC Ground?
Transcript is auto-generated.
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
