Shore Power Installation

[slode]

I want to add shore power to my Eclipse.  I have decent electrical knowledge but have not really done much with installing marine AC supply systems.  I have been reading up on this and am finding many conflicting references when it comes to proper grounding.  Seems the new standards require tying the AC green (grounding) wire to the DC ground so that any stray current to ground creates equal potentials on all the grounded metal parts.  That makes total sense when you have a motor, through hull fittings, etc. that are grounded.  But on the Eclipse there is no earth ground!!  All the negative DC leads terminate behind the fuse panel and lead back to the negative battery post, nothing tied to any fittings or other parts.  And none of the top side metal parts or through hull fittings are bonded.

I only plan to use AC current at a slip, no transformer or generator, so my thought is to keep the AC and DC circuits isolated and rely on the shore power ground and proper GFCIs in the boat to protect against shorts/incorrect polarity.  I'm pretty sure I have all the requirements for the 30A AC supply figured out (Proper 10ga cord & marine socket on the boat, dual pole 30A main breaker with polarity indication, 15A breaker for branch power, marine tinned wiring, keeping the neutral and ground wires on separate bus bars, everything running though GFCI outlet close to main...) I would expect any stray current to ground, or a bad earth ground at the supply to trip the GFCI.  With no current path to the water or unpowered metal it seems I wouldn't have to worry about stray current electrocuting anyone on board or in the water.

Can anyone with more experience tell me if I'm on the right track, or if I'm missing something that may cause harm to me, others, or my boat? 

Thanks,
Scott

[Vipersdad]

Bob23 mentioned this book in a recent post.

"Sailboat Electrics Simplified" by Don Casey.

You might want to talk to Hoopers in Afton for parts and/or advice.  I may be doing the same installation to my 19-II.  If I complete it I will have my circuits checked by a marina technician.

Hoopers Yachts
599 Manning Ave S, Afton, MN 55001
Phone (651) 436-8795
Toll Free (800) 377-8795
info@hoopersyachts.com


V.

[captronr]

I'm just curious why you want shore power?  Air Conditioning, I get that.  If its mainly for lighting, I'd change all the lights to LED. 

My last boat had OEM shore power, and only time we used it was when we dragged an A/C onboard in August in Oklahoma.  Otherwise for us, it wasn't worth it.

Of course I understand and it's ok if you just want to do it.

Ron

[slode]

I have done a lot of reading, not specifically "Sailboat Electrics Simplified" but others more technical, and all assume a system with some form of through hull ground and bonding system.  My concern with doing it "to the books" is I don't want stray current from the AC ground getting into the DC circuit with there being no earth ground.  Just want to hear if anyone has a good reason the AC ground can't be kept isolated from the DC - in this scenario. 

Reason for wanting to add it is mainly for battery charging over long weekend to week trips on lakes like Superior, Leach, and Mille Lacs.  We also have a mini fridge that fits up in the V-birth to cut down on ice stops.  A/C is a possibility as well as a small electric oil heater for those chilly spring and fall nights.

My battery charger will be plugged into a GFCI outlet on the boat so that will be protected.  When charging on the trailer at home I'll just unplug and re-plug into an extension cord

[brackish]

By new system are you referring to ELCI?  I considered converting but have not because of the same consideration you have mentioned.  In order for it to be effective protecting someone in the water it must protect against a fault that can find a conductor in the water and in order for it to protect you  (AC/DC common ground) it must have the same.  My 23 has no conductor leading to the water so the only path to ground is through the marina's shore power system.  Even my outboard is lifted up and tilted out of the water prior to plugging in.  I also don't have any AC sharing wire runs with any DC.

If you go forward with this project a good investment is a small clamp on ammeter to test your shore power cord under load when you hook up to a new marina.  Zero reading means means all those electrons that are going in are coming out, no stray leakage.  Good idea to check your neighbors too, might save a life or at least you can report it and maybe save someone an electrolysis repair when their anodes prematurely disappear. 

a good discussion about this on this thread.  http://cpyoa.geekworkshosting.com/forum/index.php?topic=7038.msg51315#msg51315

[slode]

Brackish,

Wasn't considering ELCI for reason you state of not having a conductor in the water.  Thanks!  I was pretty sure I wasn't missing something but it's re-assuring to hear it from another source that I have gathered knows his stuff.

The amp clamp is a good idea.  Might be worth getting another one to leave on board.

[Flysailfish49]

Love A/C power on a boat. Stereo, refrigeration, TV.  The list is endless.  We are putting shore power on our 23. Great way to keep the batteries maintained while waiting for the next adventure.