Duel shore power plugs

Big D · Post by **Big D** » Mon Mar 14, 2011 9:11 pm

Hey guys, on Tri Cabins, when you power up the genny, do the line 1 and 2 mains trip but power is still available to loads? Have seen this on more than one Tri, and yet another Tri that didn't do this lit up the owner when he touched one of the power inlets while the genny was running. Was thinking maybe the tripping was a safety thing. Anybody experience eigther of these?

wowzer52 · Post by **wowzer52** » Mon Mar 14, 2011 9:21 pm

Stripermann2, could you send them to me also? That would really help. Thanks

aweimer · Post by **aweimer** » Mon Mar 14, 2011 9:27 pm

Big D wrote:Hey guys, on Tri Cabins, when you power up the genny, do the line 1 and 2 mains trip but power is still available to loads? Have seen this on more than one Tri, and yet another Tri that didn't do this lit up the owner when he touched one of the power inlets while the genny was running. Was thinking maybe the tripping was a safety thing. Anybody experience eigther of these?

Doesn't do that on mine. I flip the main breaker to GEN then fire it up, either manually or when on auto. Breakers don't pop.

Big D · Post by **Big D** » Mon Mar 14, 2011 9:46 pm

Thanks Aaron. Must have been something wrong with all the ones I'm thiinking about. Can understand the breakers tripping on some, must be a fault somewhere. The puzzling thing is there being power at the inlets on the boat that didn't trip breakers. Can't be a good thing for the genny to supply power there if the vessel is plugged into shore power at the same time. I'm assuming when your genny is on that there is not power at the inlets right?

risctaker · Post by **risctaker** » Tue Mar 15, 2011 9:19 am

A correctly installed 120vac system must have blocking diodes at each of the three power sources: Port inlet, Stbd inlet and Genny (a 4th if you are also running an inverter). The diodes prevent back-feeding to the "off-line" power sources. Obviously there is something wrong with that fellow's system and he's lucky to still be walking the planet.

Stripermann2 · Post by **Stripermann2** » Tue Mar 15, 2011 9:39 am

wowzer52 wrote:Stripermann2, could you send them to me also? That would really help. Thanks

...got an email address?

aweimer · Post by **aweimer** » Tue Mar 15, 2011 9:46 am

Big D wrote:Thanks Aaron. Must have been something wrong with all the ones I'm thiinking about. Can understand the breakers tripping on some, must be a fault somewhere. The puzzling thing is there being power at the inlets on the boat that didn't trip breakers. Can't be a good thing for the genny to supply power there if the vessel is plugged into shore power at the same time. I'm assuming when your genny is on that there is not power at the inlets right?

Yes i don't run the generator with the shore power connected. The owners manual instructs you to disconnect shore power, then start the generator. That could be the issue. Generator and Shore power pushing against each other, which would be a BAD thing!

wowzer52 · Post by **wowzer52** » Tue Mar 15, 2011 5:02 pm

stripermann2, something is wrong with my outlook express, I can't send but I can recieve. here's my e-mail wowzer52@comcast.net

Stripermann2 · Post by **Stripermann2** » Tue Mar 15, 2011 5:12 pm

Done. I sent it from my Droid. If you need a faxed copy, let me know.

rbcool · Post by **rbcool** » Tue Mar 15, 2011 7:19 pm

I learned the hard way..... trying to start the genny without the mains being off kept blowing the starter fuse on the Gen, even though it was switched over to Gen side.

Jaime....how do you like the Droid?? I just git the X couple weeks ago.

Ron

alexander38 · Post by **alexander38** » Tue Mar 15, 2011 7:28 pm

Droids are

when you get it there's some real good apps and you can put navionics on it for 14 bucks and its the s@#t

Now back to getting shocked.

Big D · Post by **Big D** » Tue Mar 15, 2011 10:44 pm

Risctaker, I don't recall ever seeing diodes on a Tri but I may have overlooked them. Usually it's a spider's nest back there. I suspect though that if one is being directed to disconnect shore power first, then they eigther don't have the diodes or it's a precaution in case a diode fails. I don't have to worry about it on mine, I have the rotary source selector switch that disconnects all sources save for the one it's switched to.

prowlersfish · Post by **prowlersfish** » Tue Mar 15, 2011 10:53 pm

If your popping breakers with the get set on the some thing is not wired correctly and needs to be fixed , the should be no cross feed between the gen set and shore power . there should be a switch to isolate the gen from shore power and if wired correctly you will not have a problem . If your not sure , you may what to call in a MARINE electrician .

I have seen many genset that were not wired right ( mine include) Mine was a new install just be I got the boat and they had made several trips out to fix it for the PO ( found the receipts ) I spent hour rewiring an got it right. \

I often wonder if the Genset guys under stand boat wiring from the installs I have seen ( could be owner installs too)

I do not turn the switch to gen untill it is up and running

prowlersfish · Post by **prowlersfish** » Tue Mar 15, 2011 11:03 pm

risctaker wrote:A correctly installed 120vac system must have blocking diodes at each of the three power sources: Port inlet, Stbd inlet and Genny (a 4th if you are also running an inverter). The diodes prevent back-feeding to the "off-line" power sources. Obviously there is something wrong with that fellow's system and he's lucky to still be walking the planet.

Don't think so , A correct system will use a switch so you can not cause a feed back . never seen a set up with Diodes on a Trojan .

When you hook up a diode to a AC power source what hapens to the AC ?
( yes this is a test ) I know do you ?

risctaker · Post by **risctaker** » Wed Mar 16, 2011 10:38 am

A diode is simply a one-way valve in an electrical system that prevents back-feeding. In an AC circuit, the diode must also have some form of resistance in series with it otherwise it will overheat and possibly even explode. So blocking diodes in AC circuits limit the current flow to some degree due to the presence of this resistor in series with it. In the case of having your shore power selector switch set to "Shore", you need some method to prevent back feeding the 2nd shore power inlet. On my tri-cabin, there is a port and stbd as well as bow shore power inlets. if the selector switch is set to "Shore" all these inlets that do not have a power cord attached could be "hot" if the breakers are all ON in the panel. An isolation transformer (expensive solution) would work as well.