Taps based on 240.21 (B)

[saberger_vt]

I am reviewing a set of plans that has 3#2/0 (+ GND not important for this discussion!) coming out of a panel "1M" (125A MCB) , and splitting in a wire trough so that there are now 2 sets of 3#2/0, each set going to separate MLO panels (panels "2N" and "2S"). From each of the MLO panels they run 3#2/0 to another MLO panel (panels "4S" and "4N" respectively). I am considering this a tap which means that they need to comply with 240.21 (B)(1) and/or 240.21 (B)(2). The question is, do they need to have the first set of panels ("2N" and "2S") have to be MCB or can they remain MLO per the code?

 

[pete m.]

If these 2/0 conductors (whether copper or aluminum assuming 75 degree terminals and wire) are protected at 125 amps they would not be considered tap conductors.

Tap Conductors. As used in this article, a tap conductor is
defined as a conductor, other than a service conductor, that
has overcurrent protection ahead of its point of supply that
exceeds the value permitted for similar conductors that are
protected as described elsewhere in 240.4.

Pete

 

[Dennis Alwon]

The panels do not need to be mb panels but I would not consider this to be a tap rule situation. The wire is protected at it's ampacity the entire way so this is nothing more than a feeder splice. As long as the ampacity of the conductor is appropriate for the 125 amps there should not be an issue.

Am I correct in saying that the wires are protected at the main panel?