Hard wiring generator to boat

04FV270riverrat

So I have a portable genny and was thinking about mounting it on the swim platform with some straps to hold it down. I would like to add a plug back there then hard wire it to the existing shore power so I can just plug in on the swim platform and not have an extension cord hanging on the side of the boat. Is there a way to splice into this shore power connection?

skennelly

In a house that would be considered back feeding and dangerous and illegal.  I'd think the same applies to a boat.

Some 270's have generator wiring prewired...that would be the proper way.

04FV270riverrat

Hmmm, I didn’t see any other wiring in there. I do have the generator start switch next to the blower down in the cabin.

pistole

Shore power comes in the same way. You're just substituting shore power with powee from another electrical source , ie the genset. Nothing wrong there.

Am interested

04FV270riverrat

I have that on the panel, I just need to find the wires 

Willhound

I beleive that @frenchship did something similar but in a way that didn't cause issues. Search and you'll find the thread.

Ian

If you pull the power panel off you should see behind 3 terminal to connect in the generator source that would go to the breakers. You should wire from here to a new power socket, not splice at all.

Willhound

Yes, as per most of the other comments please DO NOT simply splice into your main power inlet for a number of important safety reasons. There are ways you can safely do it so you can switch from shore power to generator and not have the two feeds conflict.

Cableguy Greg

The wires for the generator should be in the harness that runs along the firewall between the aft cabin and the engine room. It will be a 10AWG white romex style wire. The start/stop connection should also be there. The generator location was there, unless another 270 owner with one has it in a different spot. Like Al stated, do not tap into the shore power location. 

LaRea

The switch has to make it physically impossible to be connected to the generator and grid at the same time.  Same as with a home generator switch. 

Think of the unsuspecting lineman trying to fix a power outage ... power is off, and then your genny starts pumping power into the system.  Like @skennelly said, dangerous and illegal.  

04FV270riverrat

I'll go to the boat tomorrow and look around and see if I can find the wiring in the engine room. Mine was fully wired for the genny, the switch on the cabin control panel is even wired

04FV270riverrat

Is this where the generator power comes in? If so it looks like I’ll have to run wiring back to the engine compartment.

Ian

While your panel has switches etc, it appears that it is not wired.

pistole

sorry if this is completely wrong : but what are the issues surrounding feeding current from a power source (in this case , a genset) into the shorepower feed for the boat to run her AC electrics ?

the boat doesn't know that its a genset sending power in , or does it ?

not trying to be a smart , but its something I have thought of doing for some time and its also something that is widely practised too.

skennelly

@LaRea already did a good job of explaining why.  Plenty of people disregard and do it in homes and boats I guess.  If you are willing to risk injuring someone go ahead and wire it up.

pistole

skennelly said:

@LaRea already did a good job of explaining why.  Plenty of people disregard and do it in homes and boats I guess.  If you are willing to risk injuring someone go ahead and wire it up.

He mentioned that someone fixing the line would inadvertently find power being live.

I don't follow. 

If the boat is underway and shore power is disconnected and substituted with the genset, what is the issue?

Ian

Think of a heater plugged into a wall outlet - plugged in she's live and warms up. Now splice a second plug and appliance cable to the first. The heater will heat up but the extra plug - now dangling with bare pins - is hot at 110V.

Not only is the comment "its also something that is widely practised too." scary but it's illegal.

pistole

just for clarity , I google'ed : "shore power boat portable generator". it turns out that the question of connecting a portable genset to a boat's shorepower input has been asked many times before. The replies are very interesting. The main issue seems to revolve around the lack of an earth when connecting a genset to the boat. This can apparently be overcome (I can't comment on this since my basic understanding of electrical circuits is poor). Not trying to be smart , but I am posting this to point out that : - its been asked many times before, - its been done many times before, - there is a correct way to do it.

04FV270riverrat

@pistole connecting the genset to the shore power plug on the side of the boat is fine. We are talking about having another hook up that would make the shore power port on the side live when the genset is running. That would be bad as water could get in or someone could touch it.

reneechris14

The genset can be connected to a breaker to power the panel this way the only live wire is from the gen to the panel. That way the shore power is left alone. This is the same way its done in a house properly. Double pole double throw. You can add a second plug for the gen but you have to add a switch like a battery switch.

skennelly

@reneechris14 - True that this can be done on a home...but a safety has to be put on the main breaker to make it "safe".  Backfeed  danger still applies if someone switched the main back on with the gen running it would feed power back to the utility side.

Switch would the safety in this case.

GMSLITHO

Never back feed it’s too dangerous 

reneechris14

The switch would isolate the gen to go no where. Same for shore power this how your boat is set up main breaker off shore power is only live to the switch no farther.

reneechris14

Just realized this is a 270 so the panel is ready for the wire to be done correctly.

04FV270riverrat

@reneechris14 look at the pic I posted a few comments ago. Is that connection under the panel where the generator input goes? I assume it is.

reneechris14

Yes I believe so, must use marine grade wire. 

04FV270riverrat

So I was planning on adding a 30 amp plug at the back of the boat for the genny to plug into, but since I have to use the adapter to drop it down to 125v plug, could I just use this on the back instead? I would only be able to run 1 major thing at a time anyways due to the genny size (a/c, stove or microwave). This plug would also eliminate another connection as I could just plug a short extension cord into this and the genny.

Handymans342

Then where do the wires run to from the back of this outlet? Straight to the panel? Also, I would install some sort of disconnect for this outlet right next to it

04FV270riverrat

Handy, from the back of this power input the wire would run straight to the generator side of the panel. This plug will never be live unless the genny is plugged into it

Handymans342

Good

Ian

The back end of this is what would need to be wired to the connections behind your panel as per the photo above and you would plug in a cord from the generator to this to power up the boat circuits, but considering load as noted.