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smackdaddy 04-06-2010 10:35 PM

A/C wiring the C27 from scratch
78 Attachment(s)
Okay - I need help. I'm wiring the shorepower for the Smacktanic - and I'm starting from scratch. The shore power plug is there - but no wiring at all. Judging by the wiring diagram it looks stupid simple - but what do I know?

So I'm thinking of using GFI outlets. Cool? Where should I put them? I'm thinking one in the aft dinette seat wall (where the 12V system is), and one in v-berth indention wall, so I have power forward and aft. Does anyone else have a C27 set up that I could go off of?

Also, I'm assuming I'll put THIS BREAKER in the dinette seat storage area with the 12V stuff, then distribute from there.

What else do I need to think about here?

PS - There is an old outlet looking thing in the cabin and another in the cockpit under-seat storage that both have a round 3-pin female connection. What's that about? Is it supposed to be comm? Or power?

sailingdog 04-06-2010 11:31 PM

A couple of points... first, you need to have a proper shore power panel. A good one for a boat the size of the Smacktanic is this one:

I'd also recommend getting a proper shorepower outlet. I like the newer design that looks like this:

Which is on sale over at SBO until the 12th or so.

This cord is a bit better a design than the older twist-lock ones. It also has a built-in thermostat that shuts it down if the outlet itself starts to overheat. However, you do need to buy a regular 30 amp shorepower cord and hack the end off to install the plug that comes with this one. I just installed this on my boat.

The panel needs to be within 10' of the shorepower outlet to be compliant with ABYC code. The hot and neutral wires should be connected to the shorepower ganged breakers on the panel, and the ground should be connected to the boat's 12 VDC system as well as the AC panel ground bus strip. DO NOT CONNECT THE NEUTRAL AND GROUND LINES, which would be the normal practice on a terrestrial 110 VAC system. The connection between Neutral and Ground must be made on SHORE.

The back of the panel should have a non-conductive cover, especially if it is in close proximity to the 12 VDC wiring systems.

Each circuit should have a GFCI outlet as the first outlet, closest to the panel. The additional outlets do not need to be GFCI outlets, as they are protected by the first outlet on each circuit.

Ideally, you shouldn't run high voltage and low voltage wiring together. If you have to do so, put the high-voltage wiring inside a cable loom to protect it from chafe and help identify it as high-voltage. I use color-coded cable ties to identify high-voltage wiring from 12 VDC wiring. It helps if you use YELLOW wire for the 12 VDC ground wires, since the black wire is used for 110 VAC hot wiring.

smackdaddy 04-06-2010 11:35 PM

78 Attachment(s)
Cool. Thanks Dog.

So I understand a bit more, what does the panel provide over the layout in the original diagram (breaker only)?

Freesail99 04-06-2010 11:41 PM

The panel would allow you to have more then one circuit, so if in the future if you wanted to have a microwave, you will not be popping breakers if a light is on.

sailingdog 04-07-2010 12:01 AM

The panel allows you to have THREE independent circuits, so that you can selectively pick what you want powered up.

It also gives you breakers that are sized more for the wiring loads that you'll have on each independent circuit. The double ganged breakers are 30 amp breakers, cause that is what the normal shorepower feed is. The lower three independent breakers are usually 15 amps breakers...


Originally Posted by smackdaddy (Post 589953)
Cool. Thanks Dog.

So I understand a bit more, what does the panel provide over the layout in the original diagram (breaker only)?

fairbank56 04-07-2010 06:38 AM

If your boat has a DC bonding system, I would also suggest a galvanic isolator in series with the shore power ground wire to prevent galvanic current corrosion. Also, the ABYC recommendation is that a main shore power disconnect breaker be within 10 feet of the shore power inlet. As long as you meet this recommendation, you can put the AC distribution panel anywhere you want as long as it is readily accessible and protected from weather and water splash. If you install it next to the DC distribution panel, you should provide physical protection so that anyone accessing the rear of the DC panel cannot be exposed to energized parts of the AC panel.


smackdaddy 04-07-2010 09:56 AM

78 Attachment(s)
fair - what is a DC bonding system? I've seen the galvanic isolator mentioned elsewhere but wasn't sure what drove that need. I have an OB motor (that is kept out of the water at the slip). I've understood that IB motors/shafts are one of the main issues in electrolysis(?) and corrosion so thought I was pretty safe. What else am I missing?

free - thanks for the feedback. I was just going by the original C27 wiring diagram. For our purposes, 1 circuit is actually fine as it is just a lake boat. We really only need an interior light and/or charging capabilities while in the slip. Thus far we've been using an extension cord run from the slip outlet through the deck hatch - so anything is an upgrade. In this case, do you think a panel is still necessary? Seems like a lot of money to throw at a glorified extension cord.

dog - be a little calmer with your PMs will ya? Typing that many asterisks can hurt a guy.

mitiempo 04-07-2010 11:04 AM

You have been given good advice so far. The extra breakers on the panel that dog showed will come in handy. Many AC chargers are hardwired to their own breaker. Use 10/3 marine wire from the shorepower inlet to the panel and 14/3 marine wire to the outlets or charger.

fairbank56 04-07-2010 11:25 AM


Originally Posted by smackdaddy (Post 590055)
fair - what is a DC bonding system?

Metal thru-hull fittings that are wired (bonded) together along with the negative side of the DC system. Galvanic current can occur between two boats near each other in salt water when they both have underwater thru-hull fittings connected to their negative DC system which is also connected to the shore power ground connection. This is basically a battery, two boats tied together via the shore power ground and their underwater thru-hulls. Galvanic voltage levels are generally under 1 volt and the isolator will prevent these currents while still providing protection from AC shorts on board. Sounds like you probably don't need one.


smackdaddy 04-07-2010 11:46 AM

78 Attachment(s)
Wow - great explanation fair. I had no idea.

Thanks for the feedback guys.

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