Hi All,
First, I did post the same question over at the Sailnet list. Please forgive the double post, but not sure who is looking where at this point.
this is more of a survey question than I need help, but I am also looking for feedback from those with more experience when it comes to wiring up our lovely boats. I have discovered, and undone, what I believe was a modification to my wiring that I feel was potentially very very dangerous. Curious if anyone else has found what I am about to describe, and if perhaps there is some reason I can't fathom why it was done this way.
Here's what I found. Stage one was installing a polarity indicator on my original A/C shore power panel - please don't tell me to go buy a nice Blue Sea panel - I don't have the boat bucks currently allocated and all I do with A/C is keep my batteries topped and occasionally run a light bulb or a little fan - the Blue Sea solution is on the horizon, but I have to focus on the "keep her sailing" stuff, not the big upgrade stuff. OK, so I open up my A/C panel, and discover that the bus bar that has the green wire from the A/C shore power - what I think of as the safety ground has a wire to the block of my engine, effectively tying the DC ground of the system to the A/C safety ground. My first thought is that if there is an A/C fault, it's going to go to the "green" wire, and thereby electrify everything else attached to it e.g. my engine block, and my whole DC system with 120 A/C. The wiring diagram inside my A/C panel shows no such wire grounding the "green" bus to the the boat - it shows all of it as a self contained system with the green running back to the green provided by the shore power cable. The diagram as show in the A/C panel makes sense to me, so I remove this wire (from the "green" bus bar to the engine block) that appears to have been added. Roll forward several days, I am back on Emerald, and discover that my 12 volt DC side is not working properly. I start digging around and found a negative bus bar behind the 12 volt DC panel, and it's got a wire that snakes down to the "green" bus bar in my A/C panel! I look at this and think odd thoughts I can't post, and then take the wire I had disconnected from the A/C green bus bar to the engine block, and connect it back to the 'green" A/C bus bar, and voila, my DC is working again. Still not feeling good about this, for the time being I have left the A/C panel just as it is shown in the wiring diagram inside the A/C box, which is to be a self contained system with no ties to any part of the boats structure, and all wiring feeding back to the shore power cable itself. In conjunction with this, I have restored a DC ground from the DC bus bar directly to the engine block, and have not restored the wiring connecting the DC bus bar with the A/C green bus bar in the A/C panel. I have left the only path on the "green" bus bar in the A/C panel to be the shore power cable itself, and the only path from the DC ground bus bar is to the engine block, and the two systems are currently separate.
Anyone care to comment on all this? And, to make things a little more complex, I found this link on the Blue Sea website, but I don't think it applies to me because it has an DC to A/C inverter involved, which I don't, but, it makes an interesting comment about tying the two systems together! Argh! Which end is up? Here's the link:
http://www.bluesea.com/Article_detail.asp?Section_ID=145&id=103
-David
Independence 31
Emerald
First, I did post the same question over at the Sailnet list. Please forgive the double post, but not sure who is looking where at this point.
this is more of a survey question than I need help, but I am also looking for feedback from those with more experience when it comes to wiring up our lovely boats. I have discovered, and undone, what I believe was a modification to my wiring that I feel was potentially very very dangerous. Curious if anyone else has found what I am about to describe, and if perhaps there is some reason I can't fathom why it was done this way.
Here's what I found. Stage one was installing a polarity indicator on my original A/C shore power panel - please don't tell me to go buy a nice Blue Sea panel - I don't have the boat bucks currently allocated and all I do with A/C is keep my batteries topped and occasionally run a light bulb or a little fan - the Blue Sea solution is on the horizon, but I have to focus on the "keep her sailing" stuff, not the big upgrade stuff. OK, so I open up my A/C panel, and discover that the bus bar that has the green wire from the A/C shore power - what I think of as the safety ground has a wire to the block of my engine, effectively tying the DC ground of the system to the A/C safety ground. My first thought is that if there is an A/C fault, it's going to go to the "green" wire, and thereby electrify everything else attached to it e.g. my engine block, and my whole DC system with 120 A/C. The wiring diagram inside my A/C panel shows no such wire grounding the "green" bus to the the boat - it shows all of it as a self contained system with the green running back to the green provided by the shore power cable. The diagram as show in the A/C panel makes sense to me, so I remove this wire (from the "green" bus bar to the engine block) that appears to have been added. Roll forward several days, I am back on Emerald, and discover that my 12 volt DC side is not working properly. I start digging around and found a negative bus bar behind the 12 volt DC panel, and it's got a wire that snakes down to the "green" bus bar in my A/C panel! I look at this and think odd thoughts I can't post, and then take the wire I had disconnected from the A/C green bus bar to the engine block, and connect it back to the 'green" A/C bus bar, and voila, my DC is working again. Still not feeling good about this, for the time being I have left the A/C panel just as it is shown in the wiring diagram inside the A/C box, which is to be a self contained system with no ties to any part of the boats structure, and all wiring feeding back to the shore power cable itself. In conjunction with this, I have restored a DC ground from the DC bus bar directly to the engine block, and have not restored the wiring connecting the DC bus bar with the A/C green bus bar in the A/C panel. I have left the only path on the "green" bus bar in the A/C panel to be the shore power cable itself, and the only path from the DC ground bus bar is to the engine block, and the two systems are currently separate.
Anyone care to comment on all this? And, to make things a little more complex, I found this link on the Blue Sea website, but I don't think it applies to me because it has an DC to A/C inverter involved, which I don't, but, it makes an interesting comment about tying the two systems together! Argh! Which end is up? Here's the link:
http://www.bluesea.com/Article_detail.asp?Section_ID=145&id=103
-David
Independence 31
Emerald