Main breaker required on 600A subpanel?

[DVCER]

Hi guys, first post, longtime lurker....
I am installing a 600A / 480V /12 Ckt panelboard 400' from my main 2000A switchboard ,feeding the new panel off a 600A brkr there.
What say you gentlemen, main breaker on the sub panel or no?

 

[augie47]

If the new panel is in the same building, no breaker required.
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.

Glad you came around to posting. You should enjoy the interaction.

 

[radiopet]

I agree with Gus....Just remember that IF you want to install a MCB at the location you can do that also if you wish. Many engineers design in MCB within panelboards regardless of it being required in many cases.

Where you get into a problem is when you are protecting this panel on the "supply" side with a single disconnect or 2 pole disconnect...which then exception 2 comes into play.

All panelboards are to be protected “at not greater than” their rating by a single overcurrent protective device within or ahead of the panelboard. The distinction here is the term "single“ is what sets this apart from the exceptions like #2 below. Now let’s look at the exceptions to this rule.

Exception No. 2:
Individual protection is not 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 construction should not contain more than 42 overcurrent protective devices. For the purposes of this section, a 2-pole circuit breaker or fusible switch shall be considered two overcurrent devices; a 3-pole circuit breaker or fusible switch shall be considered three overcurrent devices.

 

[radiopet]

lol....but I think I went into the process of the L & A panelboard classification removal and blah..blah..blah.......I am rambling during lunch.

 

[erickench]

The main breaker should either be in the switchboard or as close to it as possible. Remember the circuit breaker can only sense a downstream fault not upstream. If you put the CB in the sub panel it's not gonna protect much of anything except the panel.

 

[iwire]

Where you get into a problem is when you are protecting this panel on the "supply" side with a single disconnect or 2 pole disconnect...which then exception 2 comes into play.

All panelboards are to be protected ?at not greater than? their rating by a single overcurrent protective device within or ahead of the panelboard. The distinction here is the term "single? is what sets this apart from the exceptions like #2 below. Now let?s look at the exceptions to this rule.

Paul, I have no idea the point you are trying to make here.

 

[infinity]

If the new panel is in the same building, no breaker required.
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.

Glad you came around to posting. You should enjoy the interaction.

I agree with Gus. The subpanel will not require a main breaker if it's in the same building. Sorry Radio but you lost me.