Building a DC Electrical Foundation

[Maine Sail]

Did you include an AC diagram? I'm particularly interested in the AC ground to DC ground connection.

No, as stated, this is only the DC Foundation diagram.

AC Green/Protective Earth is always connected to the vessels DC ground.

It is critically important that AC White/Neutral never be bonded to AC Green except back on shore. There are a few exceptions to the Neutral to Grounding bond though. If you have an inverter or generator then this bond needs to occur only when those devices are operating and this neutral to ground bond can only be made while physically inverting for AC or physically generating AC power.

This is what a typical basic AC install would look like: (Note the green grounding wire goes to DC engine negative terminal or its bus)

 

[jssailem]

Thank you MaineSail.

 

[Scott T-Bird]

Thanks for that! I have not used AC power on my boat yet. However, I am in the process of installing an AC powered water heater and AC batt charger, so my concern for the AC side has been magnified. Years ago, I disconnected the safety ground conductor that I found clamped to the neg battery post, fearing that it had not been done properly. I resolved at that time not to even connect to shore power until I was able to verify the entire system is done right.

 

[Scott T-Bird]

Another question .... I'm confused about the lack of information about power receptacles and receptacle boxes for use with the boats interior. The only components that I find are extremely expensive, for instance a Marinco receptacle for $40 (not even GFCI) and boxes that are even more costly. Are the yellow receptacles and boxes an indication that it is suitable for exterior installation? Can you go to HD and get normal house receptacles and boxes for use inside the cabin (like the ones I find installed in my boat)?

 

[Xanthus]

What is the red device between the starter and the fuse in the start isolation circuit, and shouldn't the fuse be in between the starter and the device?

 

[Maine Sail]

Another question .... I'm confused about the lack of information about power receptacles and receptacle boxes for use with the boats interior. The only components that I find are extremely expensive, for instance a Marinco receptacle for $40 (not even GFCI) and boxes that are even more costly. Are the yellow receptacles and boxes an indication that it is suitable for exterior installation? Can you go to HD and get normal house receptacles and boxes for use inside the cabin (like the ones I find installed in my boat)?

I use plastic outlet and j-boxes and replace the steel screws with SS. As for outlets etc. I use hospital grade with tinned internals. They cost a bit more but hold up better. Bare brass does not do well in a marine application. Same for GFCI's.. The stuff from a marine store, in a Marinco package, is usually repackaged low to mid grade Leviton such as a 7599-W Leviton GFCI that costs about $40.00 in a marine package and about $10.00 from an electrical supply house...

 

[Scott T-Bird]

Great tip. I'll upgrade all my outlets while I'm at it. I plan on changing out the wiring as well. Thanks!

 

[RolfP]

Any chance I can get some opinions on my ASIS and TOBE diagrams? I diagramed the current state of the battery connections (after three owners, including me, doing what they do), and a concept of how I might use what I have plus add some things in order to at least get safe, and get closer to keep track of the state of my house bank.

 

[Hunter 34_1984]

Any chance I can get some opinions on my ASIS and TOBE diagrams? I diagramed the current state of the battery connections (after three owners, including me, doing what they do), and a concept of how I might use what I have plus add some things in order to at least get safe, and get closer to keep track of the state of my house bank.

Hi RolfP
did you ever figure out where the pos from the ACR connects.

 

[Davidasailor26]

Hi RolfP
did you ever figure out where the pos from the ACR connects.

Generally the “positive sides” of the ACR just get connected to the positive terminals of the two banks it is combining.

 

[Tim22]

Curious to know how the foundation would work if the house bank we’re LiFePO4. I’m particularly interested if this would cause problems with the emergency switch configuration?

Tim

 

[Maine Sail]

Curious to know how the foundation would work if the house bank we’re LiFePO4. I’m particularly interested if this would cause problems with the emergency switch configuration?

Tim

This particular diagram was not drawn for LiFePO4 systems. A lot of folks are hacking together or "dropping-in" LFP batteries and the systems are typically not well designed nor even safe in many cases. There is a lot more to LFP installations than just "drop-in" as many markets are suggesting..

This smoked alternator stator happened just a few weeks ago with a stock Hitachi alternator..

"But, the manufacturer said they were drop-in replacements?"

 

[amrajab]

Maine Sail,
In the diagram you created for your client (post #1, above) I noted a fuse leading from the House on/off to the DC panel. The amperage of this fuse was not stated. I also noted a 300A fuse leading from the left-most stud of the positive charge bus to the House on/off switch, presumably to protect the 2/0 gauge wire leading to the house switch. My question is this: Should the unlabeled fuse from the switch to panel be rated far lower than 300A? I'm assuming that unlabeled fuse is to protect the panel itself and this panel (if I'm not mistaken) has a max amp rating of 50A, so the fuse should be 50A or less. Does this sound correct?
Another question is this: Can I duplicate this setup on my C36 whilst still retaining the old FLA batteries (that will eventually be swapped out with AGMs) and the old 51A alternator (which will eventually be replaced with something with higher output and will also include the external regulator you described in your post)? I mainly want to know if this setup (sans new alternator and regulator) will hasten the demise of my already crappy FLA batteries.
Thank you for the great wisdom and help you've provided to all us newbies through your posts and awesome MarineHowTo website!