240.21(B)(1) Tap Rules?

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InspectorElectric

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Moyock, North Carolina, United States
The question I am posing is in regards to the 10 ft. tap rule as it pertains to panelboards. The installation I am confronted with is an 800 amp service feeding 4 panels. The engineer that designed this installation used the 10 ft tap rule to use MLO panels. At the end of the code for the 10 ft tap rule there is Informational note that refers to 408.36 for panelboards.

Am I correct in the though that these panels must have overcurrent protection that is no greater that the listing of the panel? :?
 
You are correct, the panelboard must have overcurrent protection no higher then it's rating.

Some will have instructions that they are suitable for use as service equipment when there is no more then six mains - but you don't have service conductors for the supply, though one may still be able to use it that way for feeder tap supply. But that allowance is completely out if more then six branch breakers are installed.
 
InspectorElectric said:
The question I am posing is in regards to the 10 ft. tap rule as it pertains to panelboards. The installation I am confronted with is an 800 amp service feeding 4 panels. The engineer that designed this installation used the 10 ft tap rule to use MLO panels. At the end of the code for the 10 ft tap rule there is Informational note that refers to 408.36 for panelboards.

Am I correct in the though that these panels must have overcurrent protection that is no greater that the listing of the panel? :?
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You are correct.

Roger
 
OCPD required at either the beginning, middle, or the end of the circuit.

408.36 Overcurrent Protection. In addition to the requirementof 408.30, a panelboard shall be protected by anovercurrent protective device having a rating not greaterthan that of the panelboard. This overcurrent protective deviceshall be located within or at any point on the supplyside of the panelboard.
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If the riser in this thread is the one being discussed, then the four panelboards are required to have a main circuit breaker.
A tap must end at an overcurrent device per 240.21(B)(1)(1)(b) if less than 10' and 240.21(B)(2)(2) if longer than 10' and less than 25'.
 
Yes, 240.21(B)(1) applies to the conductors only and not the panelboard. That's why the IN was put there, it's a reminder that the panelboard has to be protected separately.
 
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