Many ships have ungrounded systems, with ground fault monitoring. Single
phase panels are used (without the neutral bus), or three phase panels (120
volt delta). All circuits use 2 pole breakers. Common ground monitor is
lights from phase to ground, if the light is out the phase is grounded.

Pete Albright,
Tampa, FL

"Larry W4CSC" wrote in message
...
On Sat, 27 Dec 2003 18:15:16 GMT, Larry wrote:


Being totally unfamiliar with naval systems, the question Rob asked
still
remains: Is the neutral (in a 60 - 0 - 60 system) connected to one of
the
60 volt legs? Is it still coded white? I'm assuming that ground is
always
connected to frame or earth ground in any system.

I'm sorry but I really don't remember. The last ship I was on with
this was USS Everglades (AD-24) completed in 1952. I was on her from
1966-1969 and I'm WAY too old to remember details back THAT far,
now....

But, as I remember doing some wiring in our calibration lab, I don't
think there was a "neutral" in that system. The 120VAC was from one
wire to another and I don't think the center tap of it was connected
to anything but ship's ground, as we didn't use the 60VAC for anything
to that center tap.

In article ,
"PeteAlbright" wrote:

Many ships have ungrounded systems, with ground fault monitoring. Single
phase panels are used (without the neutral bus), or three phase panels (120
volt delta). All circuits use 2 pole breakers. Common ground monitor is
lights from phase to ground, if the light is out the phase is grounded.

Pete Albright,
Tampa, FL

"Larry W4CSC" wrote in message
...
On Sat, 27 Dec 2003 18:15:16 GMT, Larry wrote:


Being totally unfamiliar with naval systems, the question Rob asked
still
remains: Is the neutral (in a 60 - 0 - 60 system) connected to one of
the
60 volt legs? Is it still coded white? I'm assuming that ground is
always
connected to frame or earth ground in any system.

I'm sorry but I really don't remember. The last ship I was on with
this was USS Everglades (AD-24) completed in 1952. I was on her from
1966-1969 and I'm WAY too old to remember details back THAT far,
now....

But, as I remember doing some wiring in our calibration lab, I don't
think there was a "neutral" in that system. The 120VAC was from one
wire to another and I don't think the center tap of it was connected
to anything but ship's ground, as we didn't use the 60VAC for anything
to that center tap.






Pete is correct in that some on board wiring deletes the netral to earth
bonding altogether. In this situation you loose the fault current
protection generated when there is a fault from active to conductive
case of equipment. In this instance it is absolutely imperative to have
Residual Current Devices (RCD's) or GFI in NA parlance both on the shore
power inlet and the onboard generator. I just did an electrical survey
on a boat where this was the case. BTW downunder we have 240/408
single/3 phase 50 Hz systems.

John Proctor

--
John VK3JP

On Sun, 28 Dec 2003 01:13:43 GMT, "PeteAlbright"
wrote:

Many ships have ungrounded systems, with ground fault monitoring. Single
phase panels are used (without the neutral bus), or three phase panels (120
volt delta). All circuits use 2 pole breakers. Common ground monitor is
lights from phase to ground, if the light is out the phase is grounded.

Pete Albright,
Tampa, FL

Now that you mention it I do think I remember a light on our
knife-switch/screw-in fuse panel (black bakelite with wooden safety
leaning bar), that alerted you to any current to the deck, indicating
a fault.

The cal lab had a Detroit Diesel, naturally-aspirated 6-71 2-stroke
diesel driving a DC generator that originally powered the stern gun
mount and director, which was removed when the disasterous DASH
anti-sub helicopter was installed. The DC powered a big
motor-alternator through a separate manual panel to create 60 Hz, 3
phase, 440 VAC that was fed to a bank of transformers buzzing away in
the cal lab to keep us awake at night. All our Edison Lights were run
directly from 110 VDC from the DC panel through a couple of knife
switches....as Edison intended.

The whole ship would go dark because of the Electical gang's
incompetence a few times per voyage. The separately-powered cal lab
shone like a beacon in the dark, then....(c;

Larry ET1
Shop 67B, Calibration Lab
USS Everglades (AD-24)
Charleston, SC (1966-1969)

Electricians were not allowed to have keys to OUR generator
room.....hee hee. They never gave us keys to THEIR generator rooms,
after all. It was only fair.

In the Med, we used to turn the motor speed on the alternator down and
run the cal lab on 50 Hz to keep the TV picture from pulsing at 10 Hz
from the differences in scan frequencies and power supply hum....(c;
I still have reel-to-reel tapes with 50 hz hum on them!