High Leg Termination B phase?

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B

buddhakii

Senior Member
Location
Littleton, CO
I always thought the high leg of a delta service was required to be terminated on B phase excluding the meter socket but I cannot find the code reference. Just got done terminating the panels and went to put the covers on and noticed the sticker on the dead front says A phase high leg. If I'm wrong about the requirement of high leg on B phase looks like I'm gonna have to re-phase everything.
 
jumper

jumper

Senior Member
Location
3 Hr 2 Min from Winged Horses
POCO usually requires it to be on C leg.

408.3(E) Phase Arrangement. The phase arrangement on 3-phase
buses shall be A, B, C from front to back, top to bottom, or left
to right, as viewed from the front of the switchboard or panelboard.
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.

Exception: Equipment within the same single section or multisection
switchboard or panelboard as the meter on 3-phase,
4-wire, delta-connected systems shall be permitted to have the
same phase configuration as the metering equipment.

Informational Note: See 110.15 for requirements on marking
the busbar or phase conductor having the higher voltage
to ground where supplied from a 4-wire, delta-connected
system.
 
B

buddhakii

Senior Member
Location
Littleton, CO
So since this is an addition to an existing installation it looks as though I will have to re-phase the high leg to A phase correct? Not sure where it is terminated in the existing equipment which all gets replaced anyways. All the h.v. lines are owned by the customer so there is no metering equipment. Not sure if that makes a difference.
 
B

buddhakii

Senior Member
Location
Littleton, CO
Maybe this wouldn't be considered an addition but instead a replacement. Just not sure why the manufacturer would say A phase high leg when it should be B phase. Just want to make sure I'm not overlooking something. The project is at a waste water treatment facility at an old mine. I'm demoing out a 400 amp serv. disc. and replacing with 600 amp MDP with a 400am OCP that feeds an ATS. The ATS feeds a panel about 1000 feet away to run a VFD for a pump. Both panels have the sticker that states A phase high leg.
 
H

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
jumper said:
POCO usually requires it to be on C leg.

408.3(E) Phase Arrangement. The phase arrangement on 3-phase
buses shall be A, B, C from front to back, top to bottom, or left
to right, as viewed from the front of the switchboard or panelboard.
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.

Exception: Equipment within the same single section or multisection
switchboard or panelboard as the meter on 3-phase,
4-wire, delta-connected systems shall be permitted to have the
same phase configuration as the metering equipment.

Informational Note: See 110.15 for requirements on marking
the busbar or phase conductor having the higher voltage
to ground where supplied from a 4-wire, delta-connected
system.
Click to expand...

What we require is that your "B" phase be in the "C" phase position for metering purposes and to know where the high leg is in case the lines are torn from the building. After the wires leave the meter, the "B" phase is installed in the "B" phase position in the disconnect equip. :D
 
Smart $

Smart $

Esteemed Member
Location
Ohio
buddhakii said:
Maybe this wouldn't be considered an addition but instead a replacement. Just not sure why the manufacturer would say A phase high leg when it should be B phase. Just want to make sure I'm not overlooking something. The project is at a waste water treatment facility at an old mine. I'm demoing out a 400 amp serv. disc. and replacing with 600 amp MDP with a 400am OCP that feeds an ATS. The ATS feeds a panel about 1000 feet away to run a VFD for a pump. Both panels have the sticker that states A phase high leg.
Click to expand...
Hmmm... I have to wonder who manufactures the panels and whether or not the panels are listed...???
 
Smart $

Smart $

Esteemed Member
Location
Ohio
buddhakii said:
The manf. is Cutler Hammer. Pretty sure all of their panels are listed.
Click to expand...
I agree... but having a sticker stating A phase is high leg seems uncommon by my understanding. Were panels custom ordered? Perhaps they were originally custom ordered but not delivered and/or re-stocked, and never got changed. Got part numbers? Contacting CH may be your best option. At the very least they can tell you whether the stickers can be removed, and B made the high leg. They may also be able to send you the appropriate stickers rather than swapping out parts. Make sure any change is CH approved and documented.

I do not believe wiring per sticker is an option for code compliance.
 
Last edited:
jwjrw

jwjrw

Senior Member
Many old installations still have the high leg on C phase on the load side here. I have never seen one on A phase.
 
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