AC electrical problem getting crazy!!

[Boatsb]

Glad I didn't call anyone a name like that Jim. Sounds like I don't want to look it up or I will be pissed off.

I do qualify as a "boomer" though.

[Avenger]

No you don't. I Wicki'ed it.

But you need to remember your audience. This may be like the term "tranny" we discussed on the... ahem... "Old Fart" thread:

http://www.samsmarine.com/forums/showthread.php?t=16450

Sometimes the speaker isn't familiar with modern useage. It is a living language you know.

[Dan Mapes]

Mario?

Maaaarrrriiiiiiiiiooooooooooohhhhhh?


Mario?

Zot!

[Canuck Dennis]

Sorry Genesis...the following is incorrect....not all marine gensets allow gc to grounded at the gen set.





At the source of the energy ONLY the GC busbar and safety ground are bolted together. For a generator-fed system they are bolted at the generator. For a shore-fed system they are bolted on shore. An isolation transformer is an energy source (there's an air gap between the primary and secondary sides) and as such if you have one, GC and Ground are bolted there - shore ground comes only as far as the isolation transformer primary and no further. This is why you have three breakers on your generator panel with its slide lockout instead of two (for each hot leg) as you must switch GC as well.

[Boatsb]

Sorry Genesis...the following is incorrect....not all marine gensets allow gc to grounded at the gen set.





At the source of the energy ONLY the GC busbar and safety ground are bolted together. For a generator-fed system they are bolted at the generator. For a shore-fed system they are bolted on shore. An isolation transformer is an energy source (there's an air gap between the primary and secondary sides) and as such if you have one, GC and Ground are bolted there - shore ground comes only as far as the isolation transformer primary and no further. This is why you have three breakers on your generator panel with its slide lockout instead of two (for each hot leg) as you must switch GC as well.

Don't do it Dennis. You now the rules.

[Genesis]

Sorry Genesis...the following is incorrect....not all marine gensets allow gc to grounded at the gen set.


At the source of the energy ONLY the GC busbar and safety ground are bolted together. For a generator-fed system they are bolted at the generator. For a shore-fed system they are bolted on shore. An isolation transformer is an energy source (there's an air gap between the primary and secondary sides) and as such if you have one, GC and Ground are bolted there - shore ground comes only as far as the isolation transformer primary and no further. This is why you have three breakers on your generator panel with its slide lockout instead of two (for each hot leg) as you must switch GC as well.

If you have a split-phase system (120/240V) or a single-phase (120V only) and it's a US-style system then safety ground and grounded conductor must be bolted at the energy source.

If you do not bolt them then there is no path for a fault current that would otherwise flow down the alleged "safety ground." In that condition if there is a fault in any connected device line voltage will appear on the case of ALL devices that have a "ground" connection since they're connected together and yet there is no path for the energy to flow through to complete the circuit - until you, the hapless fool, provide the path! Oops.

A "bifilial" (no "grounded conductor" at all) supply is a viable option and some European systems (in particular) are designed this way. There's a solid safety argument for doing it this way as the only way to get electrocuted with such a system is to bridge both sides of the supply.

In such a system "safety ground" has no meaning as there is no reference between the supply and ground at all and thus no path for fault current to flow via a "safety ground." A boat with an isolation transformer can be wired this way internally (since the shore bolting will go no further than the primary winding of the isolation transformer) but if you do that you want two-pin outlets shipwide as there is no ground reference for safety purposes and implying that there is (or worse, interconnecting "grounds" but having no actual path for current down them!) would be a serious safety problem. Of course then you come on board with a device that has a three-pin cord designed for US shore-side use and you can't plug it in......

Since we have AC shore power systems in the US with bolted connections you either have to have an isolation transformer on board and run bifilial (no ground and no bolting) or you have to conform with the way the shore system is wired.

[rsmith]

I checked the neutral from my 2 generators is not switched and is all tied together on the same buss as the neutral from the shore feed. The only rotary switch I have is selecting gen 1 or 2.

[Canuck Dennis]

That is what I was referring to...I have such an alternator...


A "bifilial" (no "grounded conductor" at all) supply is a viable option and some European systems (in particular) are designed this way. There's a solid safety argument for doing it this way as the only way to get electrocuted with such a system is to bridge both sides of the supply.

[egaito]

Wow....just read this thread, and I'm truly exhausted, and still don't know what the resolution to the problem was!

Oh well, it is, what it is.....

Happy New Year everyone. May 2011 grant us peace, serenity, or at least a little sanity.

[Boatnut]

This is getting ridiculus. Bifilial.........right, try bifilar as in the wire typically used in magnets and coils. How in the heck does this apply to the subject matter? As for 120 they don't have it in Europe. They due use neutral and it is bonded at the source, like it should be here even on a boat. If you are using a generator then obviously the generator is the source. If you have an isolation transformer I would think all connections to shore be it ground or neutral would not exist, if they are you are not isolated, although many will dispute this.

BTW, just for the heck of it, the source is not at the pedestal on your dock, it's at the distribution source for the service. There is also a method of using diodes between neutral and ground to keep the potential voltage difference between the two at a minimum, as they will develope a voltage difference between the source and your boat especially in marinas with long docks.