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[John Fruits]

Brian Maddox posted a flickr album in this thread:
http://forums.prosoundweb.com/index.php/topic,156339.0.html
In one of the photos there are 3 PDs between the steps of the generator truck and a tree that show 3 hots but no ground or neutral connected to 2 of the PDs.  So, what's up with that?

[DavidTurner]

I'm going to speculate that, perhaps, they are using balanced power - a step down transformer that does not require a neutral.

Brian Maddox posted a flickr album in this thread:
http://forums.prosoundweb.com/index.php/topic,156339.0.html
In one of the photos there are 3 PDs between the steps of the generator truck and a tree that show 3 hots but no ground or neutral connected to 2 of the PDs.  So, what's up with that?

[Mac Kerr]

So you don't have to go through all the pages of that thread, Here is a link to the post with the photo link.

Mac

[Mark Cadwallader]

Brian Maddox posted a flickr album in this thread:
http://forums.prosoundweb.com/index.php/topic,156339.0.html
In one of the photos there are 3 PDs between the steps of the generator truck and a tree that show 3 hots but no ground or neutral connected to 2 of the PDs.  So, what's up with that?

3 phase power for chain motors (only) would be my best guess.

Edit:  a) I was looking at the wrong picture; and
         b) I didn't see the caption on the picture.
Double Fail !!

[Tim McCulloch]

I'm going to speculate that, perhaps, they are using balanced power - a step down transformer that does not require a neutral.

Or step down transformers (480v delta to 120/208 wye) - the transformer primary does not require a neutral.

[Ray Aberle]

Big phat burly AC units will also run without the neutral. But, I don't think that is the case here...

[Stephen Kirby]

I thought that the colored tape on the cable was interesting.  Didn't seem to match anywhere.

[Tom Bourke]

I thought that the colored tape on the cable was interesting.  Didn't seem to match anywhere.

If you look close the tape wrapped on the cam matches the connector on the box.  I think these are an input from a local source.  You can see a single large handle on the back side of the boxes in another pic.  Feeder probably goes to a building where the disconnect may not be easy to access.  The boxes allow the generator people to turn off the incoming power.  No ground or neutral is needed because they are derived at the transformers on the other side of the generators shown in another pic. 

[Stephen Swaffer]

If you look close the tape wrapped on the cam matches the connector on the box.  I think these are an input from a local source.  You can see a single large handle on the back side of the boxes in another pic.  Feeder probably goes to a building where the disconnect may not be easy to access.  The boxes allow the generator people to turn off the incoming power.  No ground or neutral is needed because they are derived at the transformers on the other side of the generators shown in another pic.

Unless I am looking at a different pic, I do see one ground.  One ground couldserve multiple feeders if bonding is done at the load end for the loads since it really shouldn't have any current flowing.  Neutrals would be used a as required, a ground would be required in any case to trip OCP in the event of  short.  You really can't "derive" a ground sufficient for that protection.

[Tom Bourke]

Unless I am looking at a different pic, I do see one ground.  One ground couldserve multiple feeders if bonding is done at the load end for the loads since it really shouldn't have any current flowing.  Neutrals would be used a as required, a ground would be required in any case to trip OCP in the event of  short.  You really can't "derive" a ground sufficient for that protection.

Yes there is a ground in that pic, For some reason I thought it went a different path.  I agree one run could serve multiple sets in this case.

The derived ground I was referring to is how they do a service entrance.  Usually there are few to no grounds on the utility side.  The ground for the premises is from the ground rod system and building steel to keep local ground potentials and ground path resistance low.

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