hi leg termination in panel 408.3

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PEDRO ESCOVILLA

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south texas
i've been working here as an inspector in this area for one year. i am a licensed electrician in 3 states. since i got here, i have'nt been able to get electricians to land the high leg on the b phase in the panel. they drop it on the c phase, which is the poco need. once wires leave the line side of the meter, it's consumer side, and code rules. i'm trying to reconcile this and make it right (follow the code) i've been told thats what the poco wants ( they don't dictate past the meter) i've talked with the poco about it,, they were UNAWARE of the nec requirement until i brought it to their attention. we have to start reeducating folks on this, and my bo wants to know why the code requires the high leg to land on the b phase in the panel, per code. any takers? thanks in advance all
 
Even here, I know for a long time the "C" phase was the high leg. And upgrading panel in an old building you have to keep it on "C" phase. Even now our POCO keeps the stinger on the "C" phase.

But I don't know the answer to your questions as to why it has to be "B" phase for us.
 
My first guess is that "middle" is unambiguous. No matter how you view the busbars the middle is always the middle.

On the other hand the "C" phase (third busbar) is on the right viewing from the front and on the left viewing from the back. Same applies to front to back.

(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.
 
I think the OP's problem is that his predecessors have not enforced this, and now he is the bad guy wanting to make a change.

This is nothing new in the NEC, not sure when it was changed or if it ever was allowed to use the C phase as the high leg, but it is common to see on older installations so it was a common practice at the very least. The meter needs to have the high leg in the C position to work properly, or at least at one time they pretty much were all that way - may not be the case with some meters anymore but is still the way POCO generally wants it set up.
 
My first guess is that "middle" is unambiguous. No matter how you view the busbars the middle is always the middle.

On the other hand the "C" phase (third busbar) is on the right viewing from the front and on the left viewing from the back. Same applies to front to back.

(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.
 
I don't believe that the NEC has ever permitted the high leg to be in the "C" phase position. In most cases, the high leg is actually "B" as far as phase rotation is concerned, even if it has been landed in the "C" phase position.
 
The oldest NEC I have is 1975 and it was required to be on the B phase in that issue. I'm wondering if it was required on the C phase at some point by the NEC or maybe the NEC was silent on this and electricians just used the C phase because that's the way the POCO required it. As far as I know all POCO have always required it to be the C phase in the metering equipment. I've never seen an exception to that. My observation has been that many AHJ have not enforced this, but as time goes on more do.
 
yea, ok, it comes out of the meter through a nipple to a seperate panel, not all one piece, so, due to the fact that exception 3 doesn't apply correct. bo wants to know why code requires it b phase in panel, any body got any ideas? (aside from quoted from the book, which i appreciate, but yeah, i'm being the bad guy cause its been done wrong for years and its time to change it.
 
PEDRO ESCOVILLA said:
yea, ok, it comes out of the meter through a nipple to a seperate panel, not all one piece, so, due to the fact that exception 3 doesn't apply correct. bo wants to know why code requires it b phase in panel, any body got any ideas? (aside from quoted from the book, which i appreciate, but yeah, i'm being the bad guy cause its been done wrong for years and its time to change it.
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Pre 1975 NEC the hot leg was "C" 75 throug 2011 it designates "B" with the exception to 408.3.

If you have a three phase 4 wire delta system where one leg is grounded to give you 120 volts you will have

A-B 240 volts
B-C 240 volts
A-N 120 volts
B-N 208 volts
C-N 120 volts

If you have three bars in the panel A-B-C , A and C will give you 120 to nuetral and the middle bar being the High leg will supply 208 to nuetral and perminately marked as noted in 110.15 and 230.45 and 408.3(F)
 
I think many 3 phase meters will require the high leg to be on the C phase. The NEC requires it to be on the "B" phase. So at the meter it is "C" and at the disco it will be "B"
 
fmtjfw said:
Please read "exception" in post #3
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The exception only applies if the meter and panelboard are one unit. The reason? Again, as has been said - meters are designed to require the high leg to be connected to the C position, maybe not with some newer meters, but that is the way they have been for a long time.


PEDRO ESCOVILLA said:
yea, ok, it comes out of the meter through a nipple to a seperate panel, not all one piece, so, due to the fact that exception 3 doesn't apply correct. bo wants to know why code requires it b phase in panel, any body got any ideas? (aside from quoted from the book, which i appreciate, but yeah, i'm being the bad guy cause its been done wrong for years and its time to change it.
Click to expand...

I don't know reason why it is required in B phase but I like the idea that was mentioned - no matter if the buses are left to right, front to back, top to bottom - it is always the center bus. I have a feeling this is part of why it is required to be the center bus.
 
I have taken out 240v delta center grounded panels with two sections. The top section has 3 buses (A, B, C) for the 3-phase loads. The second section has the A & C buses for the 1-phase loads. The B bus just stops halfway down.
 
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