1979 42' Grand Banks Electrical System

[CharlieJ]

I have started working on subject boat to clear a serious ground fault. I have not been able to locate the neutral bus for either shore power service or the safety ground bus.

It is unhelpful that the boatbuilder used black wire for everything.

I have a lot of experience on older boats but this one has me scratching my head.

 

[STB]

My memory is that those busses are usually either in the lower helm behind the panel or, in that boat and vintage, more often in the engine room, on the forward bulkhead on the starboard side, beneath the lower helm.

...but each boat is different, as they say!

If all else fails, maybe try disconnecting from shore power, and and any gensets or inverters or other AC power sources, opening the double pole main breakers, e.g. genset and shore, and ringing it from the neutral leg of a double pole breaker back.

 

[Rusty]

In our boat, which is one year older than yours, the neutral bus is more of a bundle. For us, the AC wiring is all on the starboard bulkhead ahead of the engine. If you follow the wires up toward the ceiling, you will likely find that the wires ago up in a bundle and end with them all connected together in a big crimp at the top. At least that is the way ours was before it was re-wired.

 

[Xlantic]

My previous boat was a 1979 GB42 as well.

Below is photograph of the forward engine-room bulkhead. Lots of wiring but not sure it is the AC circuits.

 

[wkearney99]

If all else fails, maybe try disconnecting from shore power, and and any gensets or inverters or other AC power sources, opening the double pole main breakers, e.g. genset and shore, and ringing it from the neutral leg of a double pole breaker back.

heh, time to get out the test probe.

It took 8 hours to find the windlass fuse on our EB47. Tracked the wires all over the boat. It was finally only by accident of my fidgeting tapping the probe speaker buttons and leaning a sweaty hand against a panel that I finally heard where the last point of circuit was located. BEHIND a screwed-in faceplate.

sure hope the owner is prepared for the hours you'll have to bill to track it all down...

 

[CharlieJ]

After wandering around the panelboard and what is laughingly the "busses" in the E/R, I left screaming off the boat and ran down the dock, the Owner tackled me and said "What is wrong?" I said if you are going to keep this boat, the panelboard should be replaced, two proper neutral busses and a safety ground bus established. Ballpark is $10k.

Barring that, I am going to use all the tricks of the trade to find out where the boatbuilder hid the neutral and safety ground "busses". As Rusty pointed out upthread, on his GB the "bus" was actually a "bundle".

The photo shows the problem that I am trying to correct. This is serious, very, very serious.

 

[wkearney99]

The photo shows the problem that I am trying to correct. This is serious, very, very serious.

Yikes!

I've learned over the years with electrical that unless you find it in first day's worth of qualified troubleshooting that it's probably going to be cheaper in long run to rip-and-replace. Otherwise you end up burning through a ton of billable hours to figure out almost everything involved is screwed and needs replacing anyway.

 

[CharlieJ]

@wkearney99
Agree 100%. With some new found info and a very motivated Owner doing some extensive hand over hand work, if we haven't sorted in one more day it replacement will be the least expensive and most sure way of correcting this.

 

[diver dave]

After wandering around the panelboard and what is laughingly the "busses" in the E/R, I left screaming off the boat and ran down the dock, the Owner tackled me and said "What is wrong?" I said if you are going to keep this boat, the panelboard should be replaced, two proper neutral busses and a safety ground bus established. Ballpark is $10k.



Barring that, I am going to use all the tricks of the trade to find out where the boatbuilder hid the neutral and safety ground "busses". As Rusty pointed out upthread, on his GB the "bus" was actually a "bundle".



The photo shows the problem that I am trying to correct. This is serious, very, very serious.

Looks like there are two shore cables in that pix? If so, they will likely be sharing the neutral current. Also, both would show the 11Amp unbalance.

 

[Comodave]

Looks like there are two shore cables in that pix? If so, they will likely be sharing the neutral current. Also, both would show the 11Amp unbalance.

They probably are but they should not be sharing the neutral. A lot of older boats are this way.

 

[diver dave]

Having two isolated neutrals will fix the shore power cables sharing unequally, but make it more complex inside the boat. There is now a L1, L2, N1, N2 to work with.
Maybe better to do the 240/120 50A system with just the one cable. And one neutral.

 

[CharlieJ]

@diver_dave and @Comodave

Correct. I found that SP1 current is coming back on SP1 N as well as SP2 N and vice versa. That is why the hunt for the elusive N busses and the Safety Ground bus is so essential to correcting this extremely dangerous issue.

 

[SteveK]

You are clamping a shore cable and get 11A.
Are you getting 0 if both are clamped together?

 

[CharlieJ]

@Soo-Valley
Short answer is no. This was the first of several diagnostic tests performed. I installed to break out adapters between the pedestal outlets and the shore cords so that I could clamp individual conductors or any combination thereof. There is truly 11 to 15AAC leaking into the water column.

 

[SteveK]

wow! look forward to what you find

 

[diver dave]

No diving around that boat[emoji43]

 

[Comodave]

That is really bad. Wonder if it is just from commingled neutrals or is something else going on.

 

[CharlieJ]

@diver_dave: ABSOLUTELY! The Owner is extremely conscientious, and I have thoroughly briefed him. The electrical field that is being developed could, emphasize the word could, be deadly even in the salt water that the boat is in.

 

[CharlieJ]

@Comodave: The wiring on this boat defines the phrase FUBAR. I have already found and eliminated one N > G connection. Didn't change a thing at the pedestal!!

I will post my findings here so all can, hopefully, learn a bit.

 

[Comodave]

I worked on a friend’s boat since it would trip the dock breaker on the newly wired docks. Found 4 problems, all neutrals on 1 bus, both volt meters wired to 1 neutral, neutral to ground short inside water heater and one outlet with the neutral and ground wires reversed. He said that standing in the water by the boat he felt a tingling but thought it was just cold water effect. Fortunately he was standing and not swimming.

 

[High Wire]

So you still have 11 amps going to the water with every boat breaker open including the DC side? My guess is someone tied a black 120VAC hot wire to a black 12VDC negative in a ball of electrical tape somewhere. 42 YO boat must have had a few POs. I could not walk away with that boat plugged in. A diver could work on the boat in the next slip and be killed.

 

[GB42-424]

My 1974 vintage had those "hidden" in a terminal block just below the access panel in the forward head. An inspection mirror solved my riddle.

 

[TomJRH]

1976 42' GBCL old ground and new ground. New ground bars solved my problems.

 

[CharlieJ]

@TomJRH #23
That is where we finally found the "busses". They were carefully disguised because all conductors were black!
Boat is getting a new panel and proper N and G bus bars.

 

[diver dave]

Odd to see all the very carefully laced and looped conductors, and then see that termination cluster of the white wires.

 

[CharlieJ]

diver_dave: AND if you look closely, all of the black wires are crimped into an AWG 2/0 or larger ring terminal, just as we found on the subject boat.

 

[diver dave]

In theory, all the individual wires are making up a larger stranded wire; BUT, you should do a pull test on every one to insure an adequate crimp. Not likely to be done.

 

[IWAB]

TomJRH, then the middle post in your first picture was the neutral bus, and the two outer were your grounds?

And Charlie J, I have an older GB too, but the original owners had an isolating transformer installed. But I am very interested in your outcome and hope you will continue to post to this thread, and how it was remedied. This has been a very useful thread for me.

 

[TomJRH]

No, both bars have a common ground. If you look closely at the second picture you can see the red jumper connecting the two bus bars. I chose two bars to accommodate the various size wires. I also have a galvanic isolator to isolate the boat from the dock pedestal.

 

[TomJRH]

Tried to edit my post but it failed to update. To be clear, the first picture is the "before" picture. There were way too many wires, poor terminal connectors, loose screws, etc. So remove the old bus and installed two new ones, the one on the left for the large wires and the one on the left for smaller wires. If you look close at the second picture you can see the red jumper wire tying both new busses together. So both neutral and ground wires have common termination. Also have a galvanic isolator to separate the boat from dock pedestal.