I have a 30 circuit 100 amp MB panel. Have a total of 36 cicuits installed using 7 piggyback breakers. Was kicked down on inspection for overloading the panel. Panel does not state that piggyback breakers cannot be used. Would this fall under Article 408.15 (2002)? Doug
ok i did look at the NEC 96 edition. old art. 384-15
" Number of overcurrent devices on one panelboard" Not more than 42 overcurrent devices [other than those provided for in the mains] of a lighting and appliance branch-circuit panelboard shall be installed in any one cabient or cut out box. A lightingand appliance branch-circuit shall be provided with physical means to prevent the installation of more over current devices than that number for which the panelboard was designged, rated, and approved.
so in my option here most imporat part that should read the breaker box label for listing for the numbers and types of breakers that approved for that usage
if i am off track let me know then i can correct my mistake here.
p.s. i did look at my french electrical codes and they say the same thing too.
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)
I would like to know the theoretical loads these circuits might have. For instance, are you running lots of 20 amp circuits, electric heaters, hot water heater, electric range.... or is everything gas, and you just have alot of lighting circuits? I have a feeling this is not about the # of breakers in the panel, but the size of all the conductors and the ampacities flowing through the said breakers. Some more specifics would be nice! Thanx! Brian!
I seem to recall somewhere a panel that was rated for a certain total rating of all of the breakers attached to it. I don't remember which, and I don't see why (if the calculated load and the feeder rating is less than the ampacity of the bars, who cares what the total of the CB ratings is), but if that is the listing, then that is the listing.
I have also seen panels where the instructions specifically limited the total rating of CBs connected to a single stab on the bus. This is more reasonable, since the rating of the stab might be less than that of the entire bus.
This is a listing and labeling issue - 110.3(B). If the label lists this panel for a maximum of 30 ckts, that is all that is permitted. Reading the label will tell you if you are permitted to have more than 30 ckts (breakers).