Second 30A Shore Power Connection

Hello all - looking to, as many of you have done (Hayden comes to mind), install a second 30A plug to give me some power headroom when running my installed climate control gear. (Currently, not enough headroom to even charge a laptop when running the heat!!!)

I want to run the new shore power cable to a standalone breaker panel, receiving power from the new SP connnector, then feeding power directly to the A/C. I can do the menial tasks (Installing new plug, running cable), but I'm not sure what happens on the electrical side.

Here's an educated guess...Since I'm wanting this to be a "standalone" install, I'm assuming I can connect the positive, negative, and ground leads respectively to a single main breaker panel (www.westmarine.com/buy/blue-sea-systems-...ls--P009_273_003_534) (I have a port supply account, so don't roast me for looking at west marine) From there, tie the Air Conditioning Hot/Cold Leads to the breaker/panel, pray, then flip the switch.

Can anyone punch holes in this plan for me? I don't want to burn the boat down, obviously - and I'm going to run this plan by an electrical engineer first...but a quick forum sanity check would be nice, just in case I am barking up the wrong tree on my "educated guess".

Thanks in advance, to any and all...

-JP

powersht2k,

I would install a truly isolated 30A system. i.e. 30A plug, Galvonic isolator, box with the breaker that you have selected, and then isolated A/C load breakers in the new box or panel. The new breakers would be used to power your air conditioner/s. If you do decide to co-mingle the 30A services you still need to deal with the original galvanic isolator which won't handle the load.

I am not sure which IP you have but on my 1995 IP40 Island Packet ran an extra 30A wire from the plug area in the hull to behind the electrical panel area. This was plainly indicated in my owners manual - which I "discovered" after I bought the wire and was puzzling out how to route it - -Duh!

With ref to Port Supply - - ech! - - I too am a card carrying PS member with 4 other associates in my company. Defenders beats their prices every time. Their are web sources that beat Defenders. Search Google for your galvanic isolator and breaker.

George
S/V Delicia

What you propose will work fine. Just remember to connect the AC ground wire (green) in your new AC panel to the ground pin in your existing AC panel. In addition, you should connect a 30 amp (or greater) Galvanic Isolator between the new AC ground (green) and the boat DC ground. As long as you keep the wires throughout the system in accordance with the code (white is Ac hot, black is AC neutral, and green is AC ground, you will have no problem.

PS: I am an electrical engineer.

Thanks to all for your advice! Hadn't considered the problem with Galvanic Isolation...

I have a marine services tech coming on Friday (Done work on my boat in the past) who swears he can do it for cheaper than I can source parts... I'll see what his estimate comes back as... This is a very by-the-book installer, so I anticipate he'll recommend George's "truely isolated" 30A system. If that's the case, I'm not sure he can under-cut what I wanted to pay for it.

Also - What's the consensus here regarding the "new-ish" SmartPlug? I've two friends who swear by these, but service managers with multiple installers/yards still insist upon the Marinco fittings. What's the gouge on these plugs? - and in particular, if these are truely the bees knees and better, safer, etc... then why are they not the industry standard?

Thanks again to all...

The "advantage" of the news SmartPlug is that it is constructed of stainless steel and has larger blades/sockets. Since stainless steel is not as good a conductor as copper/brass, larger blades/sockets are necessary. An advantage of using the "old" shore power connectors is that they use the same shore power cord as you existing connectors and have worked satisfactorily for many, many years.

With either connector, something to consider is reverse polarity. Preferably, the new AC breaker panel you are installing has reverse polarity protection (preferred) or at least reverse polarity indication. If not, I recommend that you first connect the shore power cord you will use for air conditioning to the existing shore power connector to verify that you do not have reverse polarity on that cord. Then move the cord to the new connector and install a second shore power cord for the remaining boat loads.