Electrical Question

[Skip]

The thread on Shore Power got me thinking about a problem I have had with occasionally blowing shore power fuzes. The mechanic says I am using the wrong procedure to hook up shore power. Basically, I close the shore breaker last on the pier to bring power aboard. Is that the correct way to do it? Should I close the ship's breaker last, or does it make any difference?

The rationale he gave was some of the older hatteras switches "leaked" some current - just enough to blow a fuze - when operating the switches. That doesn't sound right...
Thanks

 

[rwetherington]

You should always turn off the breaker on the boat first. It should always be the last breaker to turn on when connecting to the shore also. I do not think this is what is blowing you fuses but this is the correct way to connect and disconnect a shoreline.

 

[Trojan]

Try unloading some of your heavy draw items before switching on the power. Like the hot water tank, battery charger, heaters. You may be creating such a large inrush current bump that it takes out a fuse.The other thing you might do is use slow blow fuses, but unloading is best. You also may be on the low side of the dock voltage and the current will go up with the lower voltage. As stated the boats power panel is last when hooking up and first when unhooking.

BILL

 

[REBrueckner]

I agree.
BEFORE you turn on the power at your electrical panel: Check for correct voltage on all circuits and legs....say 115 and 220V. check for reverse polarity. Shut off ALL loads aboard...then turn on your main (likely 220v) switch...and gradually add load monitoring current load as you do. Sometimes one 110v leg of a 220 volt circuit makes contact...and the other doesn't....sometimes the voltage is unbalanced..maybe 135 instead of 110 volts.....USE YOUR METERS...

Likely you are blowing fuses because of surface corrosion: turn/rotate fuses in their holders perhaps every six months to scrape off surface oxidation.... tiny points of oxide cause limited contact...so a standard amount of current is forced to flow through these tiny pinpoints...they get HOT and melt fuses even though current draw is NORMAL!!!!

When replacing fuses always rotate the new fuse in the older holder to make good contact!!!!!

When ready to depart dockside and disconnect: shutoff power at your electrical panel first...then you KNOW it's off and your electrical system is isolated from dockside power. Then shut off power at the dockside pedestal; AFTER it's off, disconnect your shorepower cord and get it aboard....

 

[Maynard Rupp]

We discussed this in several threads 2 years ago. Our 1986 36C has the "optional" air conditioning. Hatteras chose to make the AC an option with its own 30 amp. inlet and seperate wiring system. When both units are running the current draw is at or above 30 amps. We frequently would blow the big "buss" fuses located below the shoreline receptacle. We make sure that we use only slow blow fuses now and run only one AC unit at a time. Of course we can run both on the gen set, but not on the shore plug. Hatteras does a great job on their electrical systems, but this installation is just wrong. We have had both units serviced, the cooling tubes cleaned, and we have checked all of our connections.

 

[UNIQUE_NAME]

i agree Maynard, i have the same issue. they went the extra mile and put a 50a breaker on the genset side. how could they do the math on 2 16k units and then give me a 30a inlet? i keep saying i will bite the bullet and convert it to 50a but the 50a cord and adapter costs are unreal.

 

[Jaxfishgyd]

My 43' came wired with 30A for the main boat but 50A to run the two 16,000 R/C units. (plus the blueprints show the same thing).

The slip I've been in in now for the past 8 years has twin 30A plugs. I could go to a bigger slip, but why spend an extra $130 just go get 50A plugs.

I changed my 50A outlet on the boat to 30A. The only time I've ever had any problem is when running both units in the wintertime, or when there's a sudden power change from the dock feed.

Never had a problem when running the two A/C units in the summertime. And 30A cords are a lot cheaper than 50A !!!

 

[rwetherington]

All of the 30 amp boat were built in High Point. If you do the math you are correct 16 & 16 = 32 and as a rule of tumb for every 1k of A/C you have an 1 amp draw, what someone forgot was the pump also pulls 5 to 7 amps. Now 16 & 16 & 5 = 37 oops that is to much.