Main Breakers

[Muneepit]

Is there a code reference that requires all lighting class panelboards to have a MCB?

 

[infinity]

What do you mean by lighting class panelboard? Unless that's something special I would have to say no it's not required.

 

[Muneepit]

To be honest, I really couldn't give you a definition of a "Lighting Class" panelboard. I was sure that I had read somewhere in the code that all "Lighting Class" panelboards were required to have MCB's in them. That would have been a couple of years ago, so I don't remember where in the code I saw it, (If I actually did). I was under the impression that all Panelboards were required to have an MCB, unless it was a feed through type panelboard.

For example: 800 amp MDP with an 800 amp MCB, feeds Panel A with a 200 amp breaker. Panel A is 100' away, it was required to have an additional MCB in Panel A?

 

[infinity]

For example: 800 amp MDP with an 800 amp MCB, feeds Panel A with a 200 amp breaker. Panel A is 100' away, it was required to have an additional MCB in Panel A?

Nope, the protection for the feeder can be at the supply end, in this case the MDP and no MCB is required for the panelboard.

 

[jim dungar]

The old term was "lighting and branch circuit' panel, while that dealt with 42 circuits, there was a requirement that some where there be a 'main device' feeding it. The 'myth' was that the panel needed to have the main 'in it'.

 

[Muneepit]

Thank you for your reply's. They were very helpful. Have a GREAT weekend!

 

[hurk27]

This was one code that bounced all over the NEC till they finally settled it into the present place of 408.36, it was in 384-16 in the 1999 NEC and was moved to 408.15 in the 2002 with some words changed, then in 2005 it was located in 408.36 with no changes to the wording, but the 2008 made a complete over haul of 408.36 along with the description of what a Lighting and Appliance Branch-Circuit Panelboard was, which was removed along with the 42 space requirement, the 2011 kept the 2008 wording intact.

So basically we went from having two different types of panel boards by the description of a Lighting and Appliance Branch-Circuit Panelboard, which required protection and the 42 breaker space limit and a power panelboard that only had line to line loads didn't require protection, but was only allowed 6 breaker handles, sub-panels still have the 42 space limitation (exception 2 to 408.36).

To now only having either a main breaker panelboard lug fed panelboard, or a service rated panelboard under the exception to 408.36 exception 1

along with eliminating the 42 space requirement unless you install it as a sub-panel (408.36 Exception 2) they also eliminated the definition of lighting and appliance branch-circuit panelboards

This section really confuse many during these changes.

 

[kwired]

This was one code that bounced all over the NEC till they finally settled it into the present place of 408.36, it was in 384-16 in the 1999 NEC and was moved to 408.15 in the 2002 with some words changed, then in 2005 it was located in 408.36 with no changes to the wording, but the 2008 made a complete over haul of 408.36 along with the description of what a Lighting and Appliance Branch-Circuit Panelboard was, which was removed along with the 42 space requirement, the 2011 kept the 2008 wording intact.

So basically we went from having two different types of panel boards by the description of a Lighting and Appliance Branch-Circuit Panelboard, which required protection and the 42 breaker space limit and a power panelboard that only had line to line loads didn't require protection, but was only allowed 6 breaker handles, sub-panels still have the 42 space limitation (exception 2 to 408.36).

To now only having either a main breaker panelboard lug fed panelboard, or a service rated panelboard under the exception to 408.36 exception 1

along with eliminating the 42 space requirement unless you install it as a sub-panel (408.36 Exception 2) they also eliminated the definition of lighting and appliance branch-circuit panelboards

This section really confuse many during these changes.

exception 2 to 408.36 also includes

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

and would not apply to most common applications where there is only one supply to the panel.

 

[Muneepit]

Main Breakers

Thank you for the detailed response hurk. So I can safely and legally install a service wireway to an 800 amp fusible disconnect, (located on the outside of a building) then go to an 800 amp rated panelboard with no MCB in the panel board.

 

[Dennis Alwon]

Thank you for the detailed response hurk. So I can safely and legally install a service wireway to an 800 amp fusible disconnect, (located on the outside of a building) then go to an 800 amp rated panelboard with no MCB in the panel board.

Yes as long as there is protection to the panel. In this case the 800 amp fusible disco protects the feeder wires to the panel.

We are assuming this other panel is within the same building as the service disconnect otherwise a disconnect or the 6 handle rule would apply at the separate structure

 

[Muneepit]

Main Breaker

Main Breaker

Yes, the panel is located in the same building. The engineer came out with a set of drawings that showed a 1600 amp service riser to a service gutter, but did not show any disconnects going to the panels, which are over 100; away. I informed him that he will be required to install service disconnects for each "sub-panel". There are two panels, one 800 amp and one 600 amp, then refeeding two existing 200 amp panels.

 

[infinity]

Thank you for the detailed response hurk. So I can safely and legally install a service wireway to an 800 amp fusible disconnect, (located on the outside of a building) then go to an 800 amp rated panelboard with no MCB in the panel board.

Yes.