feeder taps

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Ben Trueblood

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I have a situation where (4) 100 Amp panels were engineered to be fed from one feeder and tapped at each panel location. The panels are in a Condo building and are stacked one over the other on each floor. The original engineering called for conduit to be ran and wire would be pulled continuous from the Main Distribution to the first floor panel and on up to the fourth floor.

My question is if I were to run say MC cable from the MDP to the first floor panel and tapped at that location then continued on up with the MC cable would that be considered a violation of the tap rule because the wire was not contiuous? Would the measurement of the 25 ft. start from my tap location on the first floor?

Thanks for the insight.
 
First, if you use the same wire for the entire run, and if the overcurrent divice at the beginning of the run is sized for that size wire, then you are not into the tap rules. It is only a "tap," if the wire being connected to the main run is smaller, and would not normally be protected by the rating of the OCPD.

Secondly, if you are using a tap at the first panel, then you cannot use a tap anywhere further downstream.
 
Feeder Tap

Feeder Tap

Charlie just to make sure you are clear we are running 300 MCM MC cable from the MDP fed from a 225 Amp breaker. We were proposing to tap a # 1 Alum conductor off at each panel location and continue up to the next floor with the 300 MCM to the next panel and tap? Please explain where the violation is and whether it is because the wire is not continuous or ???? Thanks for the help.
 
The basic principle at work is that every conductor shall be protected from overcurrent, and that that protection shall take place at the point of origin of the conductor. The ?Tap Rules? provide an exception to that principle. They allow, under certain very specific circumstances, a smaller conductor to be tapped to a larger conductor, without providing an overcurrent device (at that junction point) to protect the smaller wire.

One of the circumstances is that once you tap into the larger wire, without putting an OCPD at that junction point, then at the next tap point downstream you must put an overcurrent device. In your case, you are not taking the second tap off of the 1/0 of the first tap. Each tap is being made off of the 300 MCM. You are allowed to tap the same conductor more than once; you just can?t tap a tap (and you are not trying to, so you are OK).

The answer to an earlier question is that the distances stated in the tap rules start at the tap point and end at the point at which you install an overcurrent device. So if at any floor level there is no more than 25 feet from the tap point to the panel, then you can use the tap rules at each floor.

It is all in 240.21(B). The second sentence in 240.21(B) is not very clearly written, but it is the one that says you can?t tap a tap.
 
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