408.3(E)(1) & (F)(1)

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Rock86

Senior Member
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new york
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Electrical Engineer / Electrician
Situation... 120/240V Delta 3-phase system from POCO. They don't have the means to provide 120/208.

Many times I have seen existing 3-phase delta panels with the "High Leg" on the "A" or "C" phase lug. 408.3E1 tells me that I have to arrange the phases "A, B, C" left to right, and that the "B" phase shall have the higher voltage to ground. Then 408.3F1 tells me I need to mark the panel... " Caution ____ Phase Has ____ Volts to Ground."

Not meeting the exception in E1... Why would they tell you that the "B" phase in the high leg, then give you the option as to which phase has what volts to ground? I have seen it many times where either "A" or "C" phase are marked as the High leg in the panel.
 
Maybe due to this wording in A:
Other busbar arrangements shall be permitted for additions to existing installations and shall be marked.
 
Rock86 said:
Situation... 120/240V Delta 3-phase system from POCO. They don't have the means to provide 120/208.

Many times I have seen existing 3-phase delta panels with the "High Leg" on the "A" or "C" phase lug. 408.3E1 tells me that I have to arrange the phases "A, B, C" left to right, and that the "B" phase shall have the higher voltage to ground. Then 408.3F1 tells me I need to mark the panel... " Caution ____ Phase Has ____ Volts to Ground."

Not meeting the exception in E1... Why would they tell you that the "B" phase in the high leg, then give you the option as to which phase has what volts to ground? I have seen it many times where either "A" or "C" phase are marked as the High leg in the panel.
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POCO doesn't follow the NFPA 70.
 
augie47 said:
Maybe due to this wording in A:
Other busbar arrangements shall be permitted for additions to existing installations and shall be marked.
Click to expand...
But that can't be followed for new installations... correct? From the meter, into the building to the panelboard.
 
I know this is a tangent question, but does anyone know why the rule for terminating the Highleg on "B" Phase?
 
Rock86 said:
But that can't be followed for new installations... correct? From the meter, into the building to the panelboard.
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IMO, it would be rare but if one added a section to existing switchgear according to the above the new addition would match the old layout in which case the sticker on the new addition would be marked other than "B".

I might add it seems much ado about nothing IMO.
 
augie47 said:
IMO, it would be rare but if one added a section to existing switchgear according to the above the new addition would match the old layout in which case the sticker on the new addition would be marked other than "B".

I might add it seems much ado about nothing IMO.
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Thanks for the help. So High Leg "B" phase it is.
 
xformer said:
I know this is a tangent question, but does anyone know why the rule for terminating the Highleg on "B" Phase?
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Looks like I'm a bit late to the conversation here but I am now dealing with this situation myself in Farmers Branch. Here's what I found on the subject from the EC & M website:

Utility equipment — The ANSI standard for meter equipment requires the high-leg conductor (208V to neutral) to terminate on the “C” (right) phase of the meter socket enclosure. This is because the demand meter needs 120V, and it obtains that voltage from the “B” phase.
 
Waltman_2020 said:
Looks like I'm a bit late to the conversation here but I am now dealing with this situation myself in Farmers Branch. Here's what I found on the subject from the EC & M website:

Utility equipment — The ANSI standard for meter equipment requires the high-leg conductor (208V to neutral) to terminate on the “C” (right) phase of the meter socket enclosure. This is because the demand meter needs 120V, and it obtains that voltage from the “B” phase.
Click to expand...

That is correct, but why would the NEC say to go from "C" Phase to "B" phase? It should make no difference which leg you use IMO. It's kind of an annoyance when trying to configure the panel with multiple 2 pole breakers.
 
Rock86 said:
That is correct, but why would the NEC say to go from "C" Phase to "B" phase? It should make no difference which leg you use IMO. It's kind of an annoyance when trying to configure the panel with multiple 2 pole breakers.
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Yes sir you're telling me! I had to rewire two thirds of the panel as I had already wrapped it up . . . or so I thought.
 
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