AC Grounding &/or Bonding

[Traveler 45C]

I don’t get it. Did I offend you somehow? If I did, sorry, it was meant as a joke. With all the differences in the terms and methods you guys were discussing I thought it be funny. Again, sorry. Didn’t mean to step on your toes.

I don’t have an iso xfrm so I can’t measure what you’ve asked. Thinking about it though, I can see that there would be a reading. With the meter across the xfmr from sec hot to pri ground I would think you’d see the full voltage. The meter would be making a connection from shore to boat.

So what are you saying, that under normal ckt conditions wiring according to the pic above is incorrect? Why? Are you saying a difference of potential exists between shore and the boat? They are both held at earth potential but there is no connection on the hot or neutrals so no current flow, which is what you want. Should a fault occur the breaker should pop. You’re protected from shock and the boat is protected from stray currents.

 

[TedZ]

You folks are all very nice...appreciated.

The Jamestown picture is wrong, i don't know why...as i said very misunderstood. ABYC E-11 doesn't show it that way nor do other experts.

Why don't you all consider looking at http://qualitymarineservices.net/ and look at #4 "Understanding the Neutral to Ground Connection." Maybe you will relate to it. Also check out the drowning deaths...very interesting.

If you think this is theory and "reality" is different that is your privilege. I respect that...happens often. However, when someone posts that his ground connector is burned off in his shore plug, or his GFI's are tripping all over the place, i don't want to be the one who tells him it is not really happening! Just bad theory! :--)

Good luck. Been fun. Hope we educated by either accepting the info or by rejecting it!!

Ted

 

[Canuck Dennis]

All generator neutrals are tied to centre pin of the isolation transformer, as is the neutral of any inverter.
Generator engines are grounded to ships ground as is ground from inverter.

All ships neutrals are switched when going from shore to ship power.

Pretty simple..
.the experts here in Vancouver are still "out" on galvanic isolators
for shore grounds, fears of electrical fires on shore power connections.

My 2c

 

[SKYCHENEY]

I don't understand how you can test the potential between the primary neutral and the secondary neutral when the neutral from the shore cord ends at the boat inlet connection. There is no neutral at the primary of the transformer just two hots and a ground.

 

[Brian Degulis]

I think you guys all have your wires crossed

I wasn’t able to do any testing yesterday as I planned; other repairs had to get done. But I did find this pic.

It pretty much says it all. It clearly shows the isolation xfmr secondary’s neutral tied to ground (the ship’s ground plate, in the water) as it should be. The generator should be wired the same as the xfmr. Notice the inverters output neutral is also tied to ground. That connection is made when the inverter is the primary power source. When not, that connection is switched out*. The bonding ckt should be tied to ground also. Note if no iso xfrm is used and operating from shore power, neutral and ground should not be tied together on board.

The article from which I pulled the pic can be found here:
Grounding and Circuit Protection for Inverters and Battery Chargers
http://www.jamestowndistributors.co...Protection+for+Inverters+and+Battery+Chargers

Here are some other good reads:

Preventing Hazardous Ground Faults on Boats
http://www.jamestowndistributors.co...e=Preventing+Hazardous+Ground+Faults+on+Boats

*Neutral (White) to Ground (Green) Bond Switching
http://www.jamestowndistributors.co...ral+(White)+to+Ground+(Green)+Bond+Switching

Well my wires aren't crossed your diagram is exactly the way I said it should be wired. And exactly the way Hat wires they're boats so we're in full agreement.

Sky what Ted is saying is that an Iso neutral will be at a diffrent potential than the iso pimaries neutral. Right ours don't have neutral on the primary side but you could do the test using the iso's earth ground on the primary side since earth ground (green) and neutral (white) are tied together in the panel that supplies the shore pedastal.

I have no idea what the point is in doing that test. They're may very well be a diffrence in potential who realy cares. The iso secondary neutral is tied to the boats seawater ground so everthing on the boat is bonded to seawater ground. It's exactly the same thing Ted say's he's doing on land based iso's except he's using earth ground instead of a seawater ground.

This seawater ground arrangement on the iso is exactly the same as your gen set no hardwire conection to earth ground. Is anyone getting shocked using they're gen set? Has anyone ever noticed swimmers floating face down and beginning to de compose around your boat while your using your gen set. Has anyone been keeping there boats hard wired to earth ground with a 200 mile teather?

If you have answered no to the above then you can only conclude this. Hat and ABYC have a safe workable arangement for Iso wiring. It's not perfect and ted may have some valid points. But IMHO ted is missing something perhaps our transformers are built diffrently than what he's familiar with for land based aplications I don't know. But I do know that testing from my boats ground to earth ground shows no diffrence in potential. And I know that the hazards he speaks of simply aren't happening.

Brian

 

[Traveler 45C]

Well Brian I didn't mean to piss you off either.

Didn't you guys see the smiley face next to the 'wires crossed' statement?

I would have enjoyed it if Hatt had wired my boat like they did all the rest. This post would never have gotten started. Since it's not, has no iso xfmr or AC safety grounds and lots of mistakes from PO's, I've got to trace all the wires I'm working with just to make sure they go where they're supposed to. I've found lots of wire nuts, elec tape, wires connected together with a nut and bolt just hangin' there, AHG!!! The boat originally had two 30a shore cords. Sometime in its past it was rewired to a single 50a, and they didn't bother to update the schematics. I hope they did that job right. I've got to go through the whole boat to check everything.

 

[Canuck Dennis]

Hope you have Calders book....

 

[Traveler 45C]

I do

 

[Brian Degulis]

Well Brian I didn't mean to piss you off either.

Didn't you guys see the smiley face next to the 'wires crossed' statement?

I would have enjoyed it if Hatt had wired my boat like they did all the rest. This post would never have gotten started. Since it's not, has no iso xfmr or AC safety grounds and lots of mistakes from PO's, I've got to trace all the wires I'm working with just to make sure they go where they're supposed to. I've found lots of wire nuts, elec tape, wires connected together with a nut and bolt just hangin' there, AHG!!! The boat originally had two 30a shore cords. Sometime in its past it was rewired to a single 50a, and they didn't bother to update the schematics. I hope they did that job right. I've got to go through the whole boat to check everything.

You didn't piss me off at all.

Brian

 

[Brian Degulis]

Not sure what your asking most of our boats are set up to run on 240V Or 120V shore power.

Brian

 

[Brian Degulis]

I'm trying to figure out when or why they decided to put isolation transformer on the boat. It seems like only the larger boats have them. Mine is 2 30amp 120 from Hat.

Brian, are you in Apollo Beach? I am in North Tampa+

Yes I'm in Apollo beach on the south side Were in N Tampa are you?

Yes it is mostly larger boats I guess they figure more equiptment more wiring just more to protect and the cost is a smaller percentage of the whole with a bigger boat.

I've had several boats without them and 3 with and there's a big diffrence in electrolysis problems and vinc wastage. And they sure come in handy to boost voltage. Seems like everyplace we go has low voltage problems. So many marinas are using 3 phase so your starting with 208V and then encountering the typical losses on the way to your boat.

Brian

 

[Brian Degulis]

We take the boat over to Jackson's in Tampa for lunch and dinner pretty often. You can tie at the hotel pier if it's open and no one's watching or at the convention center piers. I'll give you a heads up next time we're planning to go?

Brian

 

[captddis]

Brian'

Seems there are plenty of Hat owners in the bay area, maybe we can get a party going. Even if we go by land (yuck)

I have suggested a West Coast FL rendezvous or weekend but never much interest. Lets try again. I know of a number of local Hatt owners who would participate. Brian himself would need two slips.

 

[Brian Degulis]

Hopefully just one will work. We are coming to the end of the 60C project I hope to have it on the market by the end of the month.

Brian