One Service Disconnect and Two Panels

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infinity

infinity

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Looking at a 400 amp service disconnect with 400 amp fuses feeding two 200 amp panels via double lugs on the load side of the disconnect. Tap conductors (250 kcmil AL) are about 5' long. Connected load on each panel well below 200 amps. Do the two panel require 200 amp OCPD's? I say yes and quoted 408.36. Other electrician says not due to the 10' tap rule. Who gets the martini? :)
 
infinity

infinity

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Update:

Spoke to the other electrician and he told me that he had spoken to two different inspectors and they both said that the mains were not required (MLO panels OK). One guy said that "he didn't like it but it was legal". :confused:
 
augie47

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were it not for that pesky FPN and 408.36...............................:grin:
 
Dennis Alwon

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infinity said:
Yeah for me 408.36 can't be much clearer.
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So what do they have to say about 408.36.

The odd thing is there is an exception for a multiple disconnect panel so in that case you would go back to 240.21(B)(1) which, I think, would require the tap conductors to be the same size as the OCPD ahead of it.
 
Smart $

Smart $

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Dennis Alwon said:
...

The odd thing is there is an exception for a multiple disconnect panel so in that case you would go back to 240.21(B)(1) which, I think, would require the tap conductors to be the same size as the OCPD ahead of it.
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Which exception are you referring to... because I don't see what you are saying.
 
Dennis Alwon

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Here this may help.

408.36 Overcurrent Protection.
In addition to the requirement of 408.30, a panelboard shall be protected by an overcurrent protective device having a rating not greater than that of the panelboard. This overcurrent protective device shall be located within or at any point on the supply side of the panelboard.
Exception No. 1: Individual protection shall not be required for a panelboard used as service equipment with multiple disconnecting means in accordance with 230.71. In panelboards protected by three or more main circuit breakers or sets of fuses, the circuit breakers or sets of fuses shall not supply a second bus structure within the same panelboard assembly.
Exception No. 2: Individual protection shall not be required for a panelboard protected on its supply side by two main circuit breakers or two sets of fuses having a combined rating not greater than that of the panelboard. A panelboard constructed or wired under this exception shall not contain more than 42 overcurrent devices. For the purposes of determining the maximum of 42 overcurrent devices, a 2-pole or a 3-pole circuit breaker shall be considered as two or three overcurrent devices, respectively.
Exception No. 3: For existing panelboards, individual protection shall not be required for a panelboard used as service equipment for an individual residential occupancy.
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E

eprice

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408.36 requires that the two 200 amp panelboards be protected by a 200 amp (maximum) breaker. In the scenario presented in the OP, these panelboards are not being used as service equipment. That eliminates exceptions 1 and 3 from the discussion. Exception 2 allows two breakers, but the combined load cannot exceed 200 amps.

None of these exceptions in this case, remove the general requirement that the panelboards be protected at 200 amps. I guess, if each panel had no more than two breakers, exception 2 might help.
 
Dennis Alwon

Dennis Alwon

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eprice said:
408.36 requires that the two 200 amp panelboards be protected by a 200 amp (maximum) breaker. In the scenario presented in the OP, these panelboards are not being used as service equipment. That eliminates exceptions 1 and 3 from the discussion. Exception 2 allows two breakers, but the combined load cannot exceed 200 amps.

None of these exceptions in this case, remove the general requirement that the panelboards be protected at 200 amps. I guess, if each panel had no more than two breakers, exception 2 might help.
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Good catch I got caught up in the rule rather than the application of having a 400 amp disconnect ahead of the panels.
 
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