Yet another ?: NEC215.8

| Instructor says on 3p, 4-wire, delta-connected system the wild leg is | usually connected to Bravo terminal. It's almost always that way. | | Mike Holt's "Understanding NEC" says "High-leg conductors are required by | the National Electric Safety Code (utility code) to be terminated to the "C" | phase, and not the "B" phase. So take the extra time when working with | these types of systems to confirm just where the utility company connected | the high-leg." | | Does NESC not have authority to enforce or what is the deal?

here's what I've read and learned about it (I am not an electrician or an engineer):

What's called A, B, and C might be different on each side of the boundary between where NEC and where NESC have their say. It might be called "B" in the breaker panel, but be called "C" by the linemen. Since 240 delta is effectively an extension of 120/240 single phase, there would already be "A" and "B" for single phase. Then as two (or one with Scott-T) more transformers are added to bring it up to three phase, there's a new wire and it could be called "C", but be connected inside the building to "B".

We tend to write "A" on the left and "B" on the right for a horizontal depiction of single phase 120-0-120. Then the wild leg is added in the up direction, and we tend to think clockwise and label the high leg after the "A" so then it becomes "B". These are different approaches to the determination of labels, which, unfortunately, have different results. So thus confusion. I've never been able to really sort it out. One has to always check and be sure.

Which rule in the NESC are you referring to? I have the NESC in pdf form in my computer. I searched using Acrobat 6.0 for high leg, high leg delta, C-phase, c phase, connections, delta systems, and a few miore and found nothing. .

I was in the computer biz for 30 years and one thing was certain. You could never trust phasing. The high leg should be reidentified with orange tape but you still checked it ... everytime!

I don't know which rule. Just "National Electric Safety Code (utility code)" as stated in Holt's book.

"Cø high-leg" convention follows an ANSI C12 standard for socketed, self-contained and transformer-rated meters, on the North American continent. C12 metering standards may predate NEC 215 preferred high-leg-bus location. [NEC 215 permits alternate bus arrangements to "match existing," right?] May not be addressed in NESC.

?s falke

I have seen the "high leg/wild leg" installed on B and C phase locations. I have also seen it labeled red and or orange. The local AHJ and utilities have more to say about the location that the NEC does. Trust me if the utlitiy say orange and in the middle and you decide to do something else your going to wait for power until you change it.

If the there is no rule in the NESC then it reverts back to the NEC if these codes are the adopted standards. Read my article on this at:

wrote this while inspecting a $300 million power plant construction job in Healy, Alaska. I was a State inspector then and all the electricians working there were inside wireman that had been trained to do work according to the NEC. They had many questions about applying the NEC to a power plant that was supposedly exempt from the NEC since it fell under the NESC.

NEC2002 110.15 High-Leg Marking. On a 4-wire, delta-connected system where the midpoint of one phase winding is grounded to supply lighting and similar loads, the conductor or busbar having the higher phase voltage to ground shall be durably and permanently marked by an outer finish that is orange in color or by other effective means. Such identification shall be placed at each point on the system where a connection is made if the grounded conductor is also present.

Handbook commentary Added for the 2002 Code, this section now contains a requirement that appeared in 384-3(e) of the 1999 NEC. This requirement was moved to Article 110, where the application becomes a more general requirement. The high leg is common on a 240/120-volt 3-phase, 4-wire delta system. It is typically designated as ?B phase.? The high-leg marking is required to be the color orange or other similar effective means and is intended to prevent problems due to the lack of complete standardization where metered and nonmetered equipment are installed in the same installation. Electricians should always test each phase relative to ground with suitable equipment to determine exactly where the high leg is located in the system.

NEC Orange-High Leg Delta ARTICLE 110 Requirements for Electrical Installations Section 110.15 High-Leg Marking High leg delta systems that have the midpoint of one phase grounded are required to have that phase conductor marked with orange tape, orange finish or similar. This marking is only required where a connection is made and the grounded conductor is present.

no requirement for phases, usually up to the utility

signed

IBEW Electrician