Panel Protection

[T.M.Haja Sahib]

With no distinction of lightning and appliance panel now, does a panel with continuous load requires a change in its bus bar rating depending on its feeder over current protection? Thanks.

 

[david luchini]

Per 408.36, a panelboard shall be protected by an overcurrent protective device having a rating not greater than that of the panelboard. This has not changed from recent codes. The type of load doesn't change this.

 

[T.M.Haja Sahib]

Per 408.36, a panelboard shall be protected by an overcurrent protective device having a rating not greater than that of the panelboard. This has not changed from recent codes. The type of load doesn't change this.

In earlier codes where there was lighting and appliance panels and power panels distinction, the power panel did not require protection of its bus bar.

 

[david luchini]

In earlier codes where there was lighting and appliance panels and power panels distinction, the power panel did not require protection of its bus bar.

Now, I see what you are saying. You threw me off by mentioning "continuous load."

It is not true that "power panels" did not require protection of its bus bar. It was true that protection could be higher than the rating of the bus bars, just as the protection could be higher than the rating of the feeder conductors. For instance, if the power panel was supplying a group of motor loads, the feeder OCPD could be larger than both the feeder conductor rating and the panel bus bar rating. You are correct that this has changed with the removal of panel types.

However, 408.30 hasn't changed, which says that "all panelboards shall have a rating not less than the 'minimum feeder capacity' required for the load calculated in...Article 220." In my mind, this addresses the continuous load question that you are asking.

 

[T.M.Haja Sahib]

408.30 hasn't changed, which says that "all panelboards shall have a rating not less than the 'minimum feeder capacity' required for the load calculated in...Article 220." In my mind, this addresses the continuous load question that you are asking.

If the feeder to that panel board is protected by a listed 100% rated over current protective device, the panel rating can be same as that of the protective device. But if the protective device is not so listed, its rating as well as the size of the feeder is required to be increased by 125% for continuous loads . And so is the panel rating, despite the fact that the total load remains unchanged in both the cases. So the panel rating can change with the size of its feeder protective device. This seems to be illogical.