Generator on floating Dredge

[STRUT12034]

I have ran into a situation on a floating vessel (dredge) that has its own power supply on board, 480 volt generator with a 120/240 volt transformer connected to it, my question is the neutral conductor of the generator or the transformer are not bonded to anything on the dredge, I am used to the normal configuration of bonding a transformer in a building but I can't see why this wouldn't need to be bonded to the metal dredge?

 

[kwired]

I have ran into a situation on a floating vessel (dredge) that has its own power supply on board, 480 volt generator with a 120/240 volt transformer connected to it, my question is the neutral conductor of the generator or the transformer are not bonded to anything on the dredge, I am used to the normal configuration of bonding a transformer in a building but I can't see why this wouldn't need to be bonded to the metal dredge?

NEC does not apply to this vessel see 90.2(B)(1). I am not certain what standards do apply.

 

[Fulthrotl]

I have ran into a situation on a floating vessel (dredge) that has its own power supply on board, 480 volt generator with a 120/240 volt transformer connected to it, my question is the neutral conductor of the generator or the transformer are not bonded to anything on the dredge, I am used to the normal configuration of bonding a transformer in a building but I can't see why this wouldn't need to be bonded to the metal dredge?

yeah, you need things tied to "building steel" even if the building is floating....
overcurrent protection doesn't help if you get a short that can't go to ground
and trip the overcurrent protection till you grab hold of something, and become
the path to ground....

but..... cathodic protection needs to be considered... i had a customer with a
75' aluminum hulled chris craft, old one, in salt water..... and there was a
ground loop, and 10 amps of one side of a 220V ship to shore was going
into the ocean, mostly thru the prop shaft and prop, as the hull had a
thick layer of epoxy on it.... all the zincs were eaten up almost immediately,
and the bronze propeller and rudder looked like a saltine soda cracker........

i don't know enough about marine wiring to offer correct means and methods,
but i've seen what happens when power goes into water, especially salt water...
i did a very small amount of offshore oil platform, and everything there is 4160,
and grounding and bonding is a huge issue.

 

[kwired]

yeah, you need things tied to "building steel" even if the building is floating....
overcurrent protection doesn't help if you get a short that can't go to ground
and trip the overcurrent protection till you grab hold of something, and become
the path to ground....

but..... cathodic protection needs to be considered... i had a customer with a
75' aluminum hulled chris craft, old one, in salt water..... and there was a
ground loop, and 10 amps of one side of a 220V ship to shore was going
into the ocean, mostly thru the prop shaft and prop, as the hull had a
thick layer of epoxy on it.... all the zincs were eaten up almost immediately,
and the bronze propeller and rudder looked like a saltine soda cracker........

i don't know enough about marine wiring to offer correct means and methods,
but i've seen what happens when power goes into water, especially salt water...
i did a very small amount of offshore oil platform, and everything there is 4160,
and grounding and bonding is a huge issue.

When the power is coming from shore I can see potential problems, but the OP is talking about an onboard power source, there is no reason for current to flow from the vessel to the water as the point current will be trying to return to is on board.

 

[charlie b]

Marine power systems are generally ungrounded. The enclosure of a power panel will be bonded to the hull, but the neutral wire will not.