I think this is nice job.

(It is not my work. )

Bob

Once again! SEPARATION OF PHASES!!!!!!!!!!!!

Ruins all the detail work. Installer should be shot!

Retracted this rant 11/05/05, 12:34PM

[This message has been edited by sierra electrician (edited 11-05-2005).]

[This message has been edited by sierra electrician (edited 11-05-2005).]

On a second note, this photo belongs in the Violation section.

Retracted this one too. 11/05/05, 12:35PM

[This message has been edited by sierra electrician (edited 11-05-2005).]

Provided the installation is in nonmetallic conduit for its entire length, does not enter a metallic wall at the other end, and the conduits are installed in close proximity to each other, this is permitted according to 300.5 (I), Exception #2 (2005 NEC).

I still prefer to group all phases, neutral and ground into each conduit. Start going down this road, and you get others thinking there's nothing wrong with doing this, say, in parallel runs of EMT. I don't know how many times I have brought 300.20 to the attention of another sparky only to get scoffed at, especially since I look kind of young.

Funny thing, though. The smaller wires landing on the grounded bus in the back of the gear: all taped gray. In some cases, you can size a neutral according to Table 250.122 if the neutral load does not exceed the ampacity thus derived, but where's the EGC?

oh my bad sorry. I did not know the PVC rule. It's a beautiful job.

I guess I have always played it safe and never separated phases.

Rob

The EGC may be connected (hopefully ) somewhere else on the neutral bus.

To each their own but I can not agree with this.


I like to think other electricians are capable of understanding anything I can understand, I am not a prodigy.

There are 100s of rules we must know to do our job, 300.20 is just another one.

How many beginners would get to make decisions about this size installation anyway?

Bob

Two questions:
What is the small conductor on the left zip tied to the frame?
What is the conduit on the right appearing to pass through this section?

Rob

If there are no issues with inductive heating, I figure that separating the phases makes for a safer install. If something were to damage the insulation in one of the conduit sections, you won't be left with a phase-phase fault.

-Jon

Good point winie.
But if there is no fault there is no way of knowing there is a problem, and the remaining parallel runs will have to take the added load. In which case there will be some overheating.

Rob

I am going to make some educated guesses here as I did not take the picture.


Very likely to be a neutral connection for control power of GFP unit or a voltage / power quality meter on the face of the gear.


Very likely it contains the wiring between the CTs in the switch gear and a remote electric meter.

Bob

Thanks Bob.
The pic does not show whats being fed.

Rob

Quote: "How many beginners would get to make decisions about this size installation anyway?"

It's not necessarily the beginners I'm worried about. I've had countless guys with 20+ years experience insist that there was nothing wrong with separating phases in parallel conduits. They had never heard of inductive heating.

The young ones aren't so bad. Set 'em straight once, and they believe you, especially if you make them find it in the book. If nobody sets them straight, 10 years later they're sure they know everything.

I took the picture during an Infrared inspection of the electrical distribution equipment for a small manufacturing facility. It is a 2500 amp 480/277 service. It was installed 25 years ago. The picture shows the point of entrance from the utility transformer to the CT cabinet. The service is hot sequence metering. The lugs shown are the line side of the CT's. The 1 1/4" PVC carries the wires between the CT's & the remote utility meter. The small conductor zip tied on the left was for the neutral connection for GFP of the main disconnect.

Al

thanks Al
That explains the lack of visible grounding in this section.

Rob

Hot sequence metering? I guess I don't know what that is.

How about 230.8, this is one item that I see missing in a lot of installations. Don't forget 300.5(G) and 300.7(A).

With that installation being installed 25 years ago, I can see the size of the neutral conductor, but with todays concerns for neutral capacity, I doubt you will see neutrals that size.
BTW - for a 25 year old installation, it looks to be in very fine shape. That is why Capt Al's infrared inspection is so important.

Yaktx, basically hot sequence metering: The current transformers for the utility meter are before the Main disconnect switch. The only way to to service the CT's is for a utility shutdown. Most services in my area have gone to cold sequence metering which puts the main disconnect ahead of the CT's.

Al

OK, I get it. Hot sequence, that's the way it's done around here. However, I know of one municipality nearby where even two-family dwellings have a main disco ahead of the metering.