'lectrical Gremlin?

[Buccaneer]

I’ve got a ‘83, 48' Series 1 MY.
She’s got the standard 30amp120v/50amp240v set up.
I keep blowing 30 amp fuses.
Put delayed fuses in, thinking the breaker would trip B4 the fuse. Not.
I’m sitting here at the YC, using the 30 amp service and was running the saloon cruiseair heater and fridge. Doesn’t draw all that much.
Pop.

Trip the breakers on the dock and the boat. Nothing.
Switch 30 amp fuses. Nothing.

Plug in the 50 amp cord (Y splitter running off the two 30 amp lines on the dock).
Nothing.
For chuckles sake, switch the 50 amp fuses. Nothing.

I know the dock has power - to at least one of the 30 amp lines, so I plug the darn 30 amp back into that one. Nothing.

So, this has been a constant issue.
And more than a little frustrating.

I’m watching my power usage. I don’t see any spikes, at least none that I think should so regularly blow fuses. And why the fuse and not the breaker? Isn’t that what the breaker is for?

OK. I’m dumb. I don’t like electrical “things” (comes from a bad shock when a teensy weensy child; some things ya just don’t get over that easily). But, I’m a (relatively) smart, grown up adult.

What am I missing here?

If the dock only had power to one of the 30 amp lines, would not the 50 amp cord still work, albeit at reduced power?

(( BTW. After starting this, I tested that very theory, with fresh from the box 30 amp fuses, and got my power back. I'm STILL frustrated at the need to constantly refresh 30 amp fuses [and am cranky that I - apparently - used dead ones the first time])

 

[SKYCHENEY]

Don't let this go like this. We worked on a 60C that had the same issue. The inlet fuses kept blowing. It turned out to be a frayed/burnt wire right behind the inlet plug. It nearly caused a fire.

If I were you, I'd pull whatever panels necessary to look behind those plugs/fuses and see what's back there. There is a reason why these are blowing.

 

[spcoolin]

The fuse holders themselves are a weak link...They tend to heat the spring that holds the fuse tight causing it to weaken...Which makes the fuse have poor connection, heat more & fail.

Steve~

 

[Pascal]

If you try to connect a 110/120-50 cord to two 30amps outlet you will not get anything unless both 30amps outlets are on AND they are both on opposing phase

 

[Maynard Rupp]

We have those miserable fuses on both of our 30 amp electrical inlets. One is for the ship and they generally work fine. The AC is the other inlet and this one smokes those fuses quite often. My 2 AC units with the water pump draw right at 30 amps. We never pop the CBs, but regularily blow one of those awful fuses. One tome mywife was using 3 burners, the microwave, and the toaster ovin. This blew both the black wire fuse, and the whithe wire one. That was the only time that we have had fuses blow on the house. The circuit breakers NEVER pop, it is always a fuse. Some folks have switched to cuircut breakers on those lines. I don't know what we could do to make them waterproof. The explanation above, about the high resistance, sure makes sense as to why the fuses blow.

 

[SKYCHENEY]

Don't just assume that it's a corroded fuse holder. Take a look at the wiring to be sure. Just a loose screw holding the wire to the back of the fuseholder can cause high resistance and arcing. Inspection of the lines and connections from plug to panel is critical. You don't want to burn up your boat.

 

[spcoolin]

Don't just assume that it's a corroded fuse holder. Take a look at the wiring to be sure. Just a loose screw holding the wire to the back of the fuseholder can cause high resistance and arcing. Inspection of the lines and connections from plug to panel is critical. You don't want to burn up your boat.

I agree Sky...But with my A/C experience and working on Hatteras...Those holders have always been a problem...At least down here...

A few things you could do because 2-115v A/C units are at the limit of a 30 amp cord & those fuse holders:

Replace the fuse holders with 30 amp breakers...

Acid Flush the A/C condensers to bring them back to original efficiency...This will lower head pressures in cooling, and thus lower their amp draw...

Move one A/C over to the other shore line...Like trade places with the water heat, or battery charger...Preferably the WH because you wouldn't be needing it or A/C at a dock you could only plug one cord into, but you would need the charger if leaving the boat...One of these will likely not run as much as an A/C would...
The only problem with this is if you have the older SA-10 A/C pump relay...It can't be run from two different shore lines because the Double Pole Double Throw relay that is installed will get a momentary arc of 230 volts when it switches from one unit to the other, and will weld its contacts in one position.
The easiest way to tell if you have that older relay is if you have No A/C pump breaker...The SA-10 got it's power from the units instead of it's own breaker.
It's taxing memory but I'm thinking by 1983 you may have the newer PR8X relay which will have it's own breaker, and will be fine for two shoreline use...
Of course the other sure way to tell is to look at the model # on the relay box.

Steve~

 

[REBrueckner]

Sky said:
Don't just assume that it's a corroded fuse holder. Take a look at the wiring to be sure. Just a loose screw holding the wire to the back of the fuseholder can cause high resistance and arcing. Inspection of the lines and connections from plug to panel is critical. You don't want to burn up your boat.

That's EXACTLY the place to start.....before working, disconnect your shorepower from the dock...don't JUST shut power off....there is no guarantee it will stay off.....

 

[Trojan]

Don't just assume that it's a corroded fuse holder. Take a look at the wiring to be sure. Just a loose screw holding the wire to the back of the fuse holder can cause high resistance and arcing. Inspection of the lines and connections from plug to panel is critical. You don't want to burn up your boat.

Sky is spot on. Good bad or otherwise. Steve might be correct this time, but I know for fact that ANY loose connection can and will if left alone, will ether burn off, catch fire or both. Been there done that. More boats catch fire this way than any other type fire. Play it safe you know its a connection problem there are not that many in line. Check them all. It could be more than one. These are high current circuits exposed to the elements. I now check mine twice a year. One fire was enough.

Bill

 

[Genesis]

As others have noted, pull that apart right now and figure out what's going on.

If you're popping fuses and there's a bad connection causing an overheat you're very, very close to a fire getting going in there. That's one of the "good features" of the fuse system by the way - it will, most of the time, open before it can get hot enough to get something lit.

Most of the time.

You've been given fair warning and need to figure out what's up - pull it apart and inspect everything CAREFULLY.

 

[SKYCHENEY]

Here is what that 60C looked like when we opened it up.

There were no other symptoms other than blowing fuses.

 

[spcoolin]

Here we go...Steve...as he said before...Fully agrees !!!!

Check the dog gone connections (i'd say different than dog gone like f'in)

But dude....Those ole 30 amp fuse holders...Well they ain't the greatest...

If your's are discolored on the caps where you can see...Well that's pretty much tellin ya...The holder is S@&%t....But what else can I say DUDE ?

It's the truth & I'm...Well...Not a DUDE...Just making a fun point is all....

Steve~

 

[Buccaneer]

The message has been received and Understood. I'll look this weekend.
(BTW ... thanks to all of you. Nice to know "idiot" questions really aren't so dumb after all...)