120V System?shorting out

[bruceb58]

Re: 120V System?shorting out

So what's that red wire that is going down to the neutral bus? Or is it just hanging there?

 

[wjob]

Re: 120V System?shorting out

Thanks Bob for posting these photos.
Re: the three shots: Overall shot of the 115 VAC Panel, close-up of the two 40 amp #1 Dock Power Breakers, and close-up of the 115 VAC Load Center

In the overall shot, bottom right, cover still on, are the two 40 amp #2 Dock Power Breakers. So, I can come in with two separate 30 amp cables, then I would control by the white panel, top right, where I have option of controlling the AC and/or Refrigeration on either #1 or #2, or a combination of the two. If I was not hooked up to shore power and had generator going, I would have all those three switches up on the #1 Dock Power Breakers to give me AC, Refrigeration and receptacles. Top left is just the right edge (other part hidden behind sliding door) of one of the 115 VAC Volt Meters that confirms shore power coming in. White switch to the right of meter cuts off shore power and throws everything on to generator. Round meter to right is an hour meter and under generator switch is a battery charger red signal.

Please note that the red paint in both close-ups was from a clean-up and Rustoleum primer job I did years ago and I don't believe they are any more corroded now than they were after I did it, and they have worked fine for years, until now. At the time I did the clean-up, I wanted to replace the electric boxes but decided not to when I realized how involved it was going to get and plus the fact, I had no problems. That Grey panel is 3/4 " marine ply that is about 5 ft long by about 3 ft high and has very little room behind it when you unfasten it and tip it forward.

The 115 VAC Load Center is the one with the five breakers, pulled one the other day, thus the loose wire. The bottom three are the ones that control the various receptacles around the boat.

Those green ground wires in the #1 Dock Power Box are fastened to a stud which I guess either grounds to the box or, more likely, goes through the box to another green grounding wire which runs to the nearest bonding point. I?m thinking maybe my next step is to find that bonding point and check it for continuity as I work back toward the boxes?

Bill

 

[wjob]

Re: 120V System?shorting out

That red wire was put in by the previous owner as the neutral for a stereo set, which runs off a 15 amp breaker, which I pulled several days ago and accounts for the loose black wire laying on the bottom of the box.

Bill

 

[bruceb58]

Re: 120V System?shorting out

Another thing that bothers me is there are 40 amp breakers in the system. You only have a 30 amp service total. Again, not good.

I don't think that is a problem. The 30 Amp breaker will blow to protect the feed cable.

 

[wjob]

Re: 120V System?shorting out

Pulled each of the three outlet breakers off the bar (took them out of the box), and again took readings at the Galley outlet and the Port outlet and got the same readings as before: Looking straight into outlet, left slot to ground reads .096, right slot to Grnd. is Inf.

Then I actually removed the black hot wire from the Galley outlet breaker and the reading at the outlet is still: Looking straight into outlet, left slot to ground reads .096, right slot to Grnd. is Inf.

I didn?t bother taking the black wire out of the other 2 outlet breakers, I can if need be and I didn?t try to locate and remove the Galley outlet neutral wire from the bus bar?

Bubba, re: some of your comments, No one has fussed with any of the wires so that is not the problem; that #1 wire is in good shape...looks like someone wrapped it with black tape as it exits the box; the box that looks rough needs to be cleaned up, and I will, but it's been that way for years.

Suggestions?

Bill

 

[bruceb58]

Re: 120V System?shorting out

Just to be sure what you are measuring here. 0.096 is on the 2 megaohm scale? If true, then you are measuring 96K Ohm which would be a little over a milli amp current going to ground. Not sure but that seems too small to trip a GFI normally. That being said, if there are multiple circuits doing the same thing, you might get over the GFI's threshold and cause it to trip. This is not quite in my area so some of you other guys should chime in.

 

[bruceb58]

Re: 120V System?shorting out

The task of any breaker is to protect the wiring it feeds. Assuming another, smaller breaker is going to protect that wiring defeats the purpose of having a breaker.

Maybe I misunderstood. Weren't you referring to the 30A breaker from the dock feeding the boat?

 

[seabob4]

Re: 120V System?shorting out

Remember Gents, the purpose of a GFCI is to measure the current flow between Neutral and Hot, compare the back and forth, and if there is a difference of, say, 5 mA, it will trip. Evidently, there is an alternative means for current to travel in Bill's system, whether it be through chafing, the ground studs on the enclosure, whatever, the GFCI's are detecting it.

Sound's like it's time for some serious troubleshooting, Bill. Something has changed over time...I don't think it's at your outlets, I think it's at your load center. Some Neutral, somewhere, is coming in contact with a Ground...

 

[bruceb58]

Re: 120V System?shorting out

Not sure where this boat is but if its in a moist environment and with all the dust and dirt in that box...maybe enough leakage current to cause the problem.

 

[wire2]

Re: 120V System?shorting out

Just to be sure what you are measuring here. 0.096 is on the 2 megaohm scale? If true, then you are measuring 96K Ohm which would be a little over a milli amp current going to ground. Not sure but that seems too small to trip a GFI normally. That being said, if there are multiple circuits doing the same thing, you might get over the GFI's threshold and cause it to trip. This is not quite in my area so some of you other guys should chime in.

True; a GFCI is required to trip after sensing ~6 to 18 mA of leakage. This is based on the "let go" current threshold in people as established by UL.

Something that hasn't been touched on in this thread yet, is that the resistance measurements are being made with a low voltage DC source (9v) in the multi meter. It won't show capacitive or inductive leakage that may be present in the circuits on 115vac. A GFCI will add them all up, and trip, if over 6 mA.

A 500v insulation tester is the next piece of equipment I'd pull out of my trunk for this one. I'm confident it will find much lower resistances than 80K.

 

[seabob4]

Re: 120V System?shorting out

So Bill, based on the pics, the advice, and the knowledge given here, sounds some re-wiring is in order here...

 

[wjob]

Re: 120V System?shorting out

Wow, I didn?t expect all these problems! I?m not going to be able to fuss with it tomorrow until possibly late in the day, then I might just pull the damn drain plug and say goodbye.

Bubba, your assumption that the box has been in that condition for some time is correct. Every thing was working fine until several months ago when I lost the 115 VAC in the boat. I replaced the foot long heavy duty extension cord which comes off the GFI and to which the 30 amp dock cable plugs into, that solved the problem, but I don?t think at that time the GFI was really functioning. I believe it was locked in the live mode, but it worked fine for at least two months. So, last week it acted up again and I decided it was time to change the GFI.

Question?Since I?m sure this was working fine with a non functioning GFI for several months, how would I get in trouble if I tried replacing the GFI with a regular 15 amp outlet and made all the load center circuit breakers 15 amps. It sounds like the resistance readings are so low that it?s not a big problem. I know it?s not right, but? I?ve lived on the water for years without GFI?s, who knows what was going on in those old wood boats.

According to my wiring diagram, they are showing a #8 (weight) black wire running from the boats inlet fitting to the 40 amp breaker than on to the hot bar in the load center box, a #8 white comes in and goes to the other 40 amp breaker than on to the neutral bus bar in the load center box, the Grn ground wire comes from the main inlet grnd terminal to the 40 amp box, then on to the load center, then to the nearest bonding point, which I need to find. Could this AC grounding wire attach to the same grounding stud as the DC engine grounding wires, or to ask it another way, would the bonding strip be tied to the same ground as the DC grounding wires? It?s been a while since I?ve had to fuss around in the bilge and I can?t remember if the two are tied to the same ground.

Would that 500v insulation tester really help diagnose the problem beyond where we are right now?

Thanks again for all the input.

Bill

 

[wire2]

Re: 120V System?shorting out

The #8 AWG wire is good for 40 amps, so that's fine. Although the fact that the shore power is limited to 30 amps makes the 40's a bit redundant.

It's not required to take a neutral through a breaker, (is also redundant, 2 breakers are in series with load in between), I expect that was originally done just in case someone mixed up line and neutral and had the white wire hot. I've seen it done a few times, just not on a boat.

An insulation tester will show things an ohmmeter can't, because of the voltage used. (Also called a "Megger", a brand name). Most electrical contractors will have one.

Bill, you described taking readings from your receptacles referenced to left and right slots, but we don't know (I don't anyway) if that was with the ground up or down. The distinction is whether the left slot was supposed to be hot or neutral. A better reference is whether the slot is small or large. The small one is hot, has the brass screws on the side.

The bottom line appears to be that you *should* get an electrician involved, preferably one with some marine experience.
Or, you could replace the boxes/wiring yourself, then have a pro in to verify your work?

 

[seabob4]

Re: 120V System?shorting out

Bubba,
That was an interesting link...

 

[wjob]

Re: 120V System?shorting out

Question?Since I?m sure this was working fine with a non functioning GFI for several months, how would I get in trouble if I tried replacing the GFI with a regular 15 amp outlet and made all the load center circuit breakers 15 amps. It sounds like the resistance readings are so low that it?s not a big problem. I know it?s not right, but?

Could this AC grounding wire attach to the same grounding stud as the DC engine grounding wires, or to ask it another way, would the bonding strip be tied to the same ground as the DC grounding wires? It?s been a while since I?ve had to fuss around in the bilge and I can?t remember if the two are tied to the same ground.

Can someone answer the above questions plus one more, what would happen right now assuming everything was hooked back-up the way it was several days ago before I started fussing with things, with all breakers on and with the generator running and switched to carry the load from the six breakers in the load center? Also, will it tell us anymore if hooked into the GFI shore power, I only turned on the top two breakers in the load center, one of which controls the electric range and the other, the hot water heater?

Re: Wire's question, The ground holes on the receptacles are below the two slots.

Re: Bubba's suggestion on the isolation transformer, believe what you meant was cut the wires after they come into the boat through the #1 Receptacle, between there and the 40 amp box? There'd be no change to the 30 amp dock cable which runs from the GFI to the boat, nor to the #1 Receptacle on the side of the boat? What would I do about the #2 Receptacle, could it be hooked into the same transformer and would there be any other new wiring required to handle the generator? That msnbc link you provided just takes me into an msnbc news page, nothing to do with a transformer?

Also, I picked up from Home Depot today the best Multimeter they have, described as: "Phase Rotation-True RMS
HZ-MFD-Auto Off"
Highest Resistance scale is 200M. It was $100 so I won't keep it if it's not going to do that much more for me? They didn't have any insulation testers nor did the electric supply house at which I stopped. My current meter is the $30 variety.

Do appreciate everyone's input.

Bill




















Every ones thoughts are much appreciated.

Bill

 

[bruceb58]

Re: 120V System?shorting out

I only turned on the top two breakers in the load center, one of which controls the electric range and the other, the hot water heater?

Hmmmm....hot water heater! At least with hot tubs with electric heaters, those are notorius for kicking off GFIs. Not sure with ones on boats. Will it ever blow if the hot water heater is not on?

 

[wjob]

Re: 120V System?shorting out

Bruce, I've run so damn many tests with the OHM meter that they start to run together. Believe seveal days ago when I was hooked up to the GFI, with the two 40 amp breakers on, but all five breakers in the Load Center off (the three receptacle ones plus the range and the hot water htr), the GFI did not trip. It tripped everytime I would throw on one of the receptacle breakers, I never did try the range or hot water htr breaker in the "on" mode, that's my question, should that test tell us anything we don't allready know?

Bill

 

[wire2]

Re: 120V System?shorting out

....
Re: Wire's question, The ground holes on the receptacles are below the two slots.
....
Also, I picked up from Home Depot today the best Multimeter they have, described as: "Phase Rotation-True RMS
HZ-MFD-Auto Off"
Highest Resistance scale is 200M. It was $100 so I won't keep it if it's not going to do that much more for me? They didn't have any insulation testers nor did the electric supply house at which I stopped. My current meter is the $30 variety.

Ok, that means the left slot should be neutral, right is line. (hot).

That meter has lots of options that you'll probably never use.
Phase Rotation- Tells which direction a 3 phase motor will go
True RMS-(Root means square)The effective voltage value of a sine wave
HZ- Frequency, (Hertz) as in 60 cycle
MFD-The value of a capacitor in Micro-Farads.

Better to use the $100 for panel replacement

You probably won't want to buy an insulation tester for just this one app, they run $500 to $1500. I was thinking you might be able to get a local electrician to come over to the boat and bring one, for a case of beer.

 

[wjob]

Re: 120V System?shorting out

Bill, if you want to continue testing you need to disconnct the three troubled circicuts (in the panel) and then test them for resistance between hot-neutral-ground.

I assume this means I have to actually remove the black hot wires from their breakers or is it enough to just pull the breakers off their bus bar? Do I also need to remove the matching white neutral wire from the neutral bus bar or can I leave all the whites and greens as they are, hooked to the bus bar?

Bill

 

[wjob]

Re: 120V System?shorting out

Do I also need to remove the matching white neutral wire from the neutral bus bar or can I leave all the whites and greens as they are, hooked to the bus bar?

Correction...the greens obviously are not hooked to the neutral bus bar, they are hooked to the grounding stud.