409.102(b)

[don_resqcapt19]

Proposal:
(B) Phase Arrangement. The phase arrangement on 3-phase horizontal common power and vertical buses shall be so that when the leads of a phase rotation meter are connected A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the industrial control panel that the phase rotation meter shall indicate a clockwise rotation. The B phase shall be that phase having the higher voltage to ground on 3-phase, 4-wire, delta-connected systems. Other busbar arrangements shall be permitted for additions to existing installations and shall be marked.

Substantiation: [FONT=&quot]
As this section is currently written it has no meaning. It appears that the intent is to require a clockwise rotation. If this is not the intent, then the section does not accomplish anything as the terms A, B and C are only arbitrary terms and the section should be deleted from the code.[/FONT]

 

[SEO]

Proposal:
(B) Phase Arrangement. The phase arrangement on 3-phase horizontal common power and vertical buses shall be so that when the leads of a phase rotation meter are connected A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the industrial control panel that the phase rotation meter shall indicate a clockwise rotation. The B phase shall be that phase having the higher voltage to ground on 3-phase, 4-wire, delta-connected systems. Other busbar arrangements shall be permitted for additions to existing installations and shall be marked.

Substantiation: [FONT=&quot]
As this section is currently written it has no meaning. It appears that the intent is to require a clockwise rotation. If this is not the intent, then the section does not accomplish anything as the terms A, B and C are only arbitrary terms and the section should be deleted from the code.[/FONT]

I agree with what your saying but can you provide any documentation about problems arrising from this ? You would have to make sure that the POCO also followed the same rules as to A,B,C rotation as well.

 

[barbeer]

I agree with what your saying but can you provide any documentation about problems arrising from this ? You would have to make sure that the POCO also followed the same rules as to A,B,C rotation as well.

Good luck with that! They want different than we must enforce as it is! Here anyway.

 

[charlie]

OK, we have a 3000 ampere service and the rotation is backward. No problem, the electrician has to just swap two phases because we are not going to do it for you. You are correct, unless you can get ALL of the electric utilities to agree to that, it ain't happen'. This will have to show up in the NESC for the electric utilities to agree.

If this is a pole mounted bank, reconfiguring the primary may be very difficult and actually take a primary roll up the line to get it done. If this is a pad mounted transformer, the primary would have to be swapped if the dressed and terminated cables will reach.

 

[weressl]

Proposal:
(B) Phase Arrangement. The phase arrangement on 3-phase horizontal common power and vertical buses shall be so that when the leads of a phase rotation meter are connected A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the industrial control panel that the phase rotation meter shall indicate a clockwise rotation. The B phase shall be that phase having the higher voltage to ground on 3-phase, 4-wire, delta-connected systems. Other busbar arrangements shall be permitted for additions to existing installations and shall be marked.

Substantiation: [FONT=&quot]
As this section is currently written it has no meaning. It appears that the intent is to require a clockwise rotation. If this is not the intent, then the section does not accomplish anything as the terms A, B and C are only arbitrary terms and the section should be deleted from the code.[/FONT]

I have a general beef with repeated, identical rules (ex. 408.3(F). The same rule is(should be) applicable to all like applcations and should be collected in a general rules place, close to the front. Like defintitions is located up front, the basic rules of electrical installations and equipment should be grouped as such. It may make the code more user friendly?

 

[charlie]

Mr. Weress, is there a proposal in the offing?

 

[weressl]

Mr. Weress, is there a proposal in the offing?

No, Thank you Charlie for asking, but I am already married and not gonna go through THAT again.....:grin:

 

[charlie]

Raspberries to you too.

 

[Cold Fusion]

(cut)[FONT=&quot]It appears that the intent is to require a clockwise rotation. (cut)[/FONT]

I never intrepreted it that way. I always figured the NEC doesn't care what the rotation is, it just should be consistent throughout the facility. Which I think is a good idea. The rotation, CW or CCW, is just a design issue and in my mind - not even particularly important.

As I recall, in the mid 80's AB offered a back-to-back 2100 MCC that had a common horizontal bus. They only offered it for a few years.

This gave an opposite arrangement (and rotation) depending on which side one was on. Really never looked like a good idea to me. And shortly after that, the NEC changed to prohibit this arrangement - and AB quit making it.

JAO - I like the way it reads.

cf

 

[weressl]

I never intrepreted it that way. I always figured the NEC doesn't care what the rotation is, it just should be consistent throughout the facility. Which I think is a good idea. The rotation, CW or CCW, is just a design issue and in my mind - not even particularly important.

As I recall, in the mid 80's AB offered a back-to-back 2100 MCC that had a common horizontal bus. They only offered it for a few years.

This gave an opposite arrangement (and rotation) depending on which side one was on. Really never looked like a good idea to me. And shortly after that, the NEC changed to prohibit this arrangement - and AB quit making it.

JAO - I like the way it reads.

cf

It is still being manufactured, maybe not by AB but others.

I was shocked to learn - eons ago - when I came to this Country that the motors need to be rotation 'checked'. Wouldn't consistent phase rotation in panel, marked cable phases and rotation coded motor leads would produce consistent installation where check is not needed? If the EU can do it why can't we? Anyone with long memory has an idea why this was never done?