Circuits for panelboard

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keithcalhoun

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I seem to remember that a panelboard can only have the number of overcurrent devices based on the amp rating divided 5 amps. Therefore a 200 amp panelboard should only have 40 overcurrent devices. Note that a two pole breaker counts as two devices. All I can find in the 2005 code book is article 408.35 indicating that no more than 42 can be in a given enclosure. Am I loosing my mind or is this 5 amp/device in the book somewhere else. The primary issue I'm dealing with is the use of double breakers in a given box. Based on the number of spaces in a panel, you can get twice as many "circuits" and devices as the number of spaces but does this breach the code requirements as long as it is less than 42? Obviously the load must be less than the rating of the pane. Any help on this question.
 
Re: Circuits for panelboard

I have seen many 150 amp panels with 40 spaces so no idea where you got that from.Often the panel comes with optional main breakers 150 or 200.I have yet to see a panel using listed breakers let you go over 40.Not saying that you could not find some piggybacks to give you 80, but they will not be listed for use in your panel and is a violation.
 
Re: Circuits for panelboard

All that matters is the calculated load, not the number or size of the breakers as long as you do not exceed 42 excluding a main.
 
Re: Circuits for panelboard

usually if its a 30 /40 panel it means you can install 30 normal size breakers or and usually at the bottom of panel it will accept 10 piggybacks.You will see a differance on the bus bar.
 
Re: Circuits for panelboard

There is a limit of 42 circuits for a single enclosure, but this limit only applies to ?lighting and appliance panelboards.? If fewer than 10 percent of the overcurrent protective devices are for lighting and appliance branch circuits, then there is no limit. Reference 408.15.
 
Re: Circuits for panelboard

Originally posted by charlie b:
There is a limit of 42 circuits for a single enclosure, but this limit only applies to ?lighting and appliance panelboards.? If fewer than 10 percent of the overcurrent protective devices are for lighting and appliance branch circuits, then there is no limit. Reference 408.15.
Click to expand...
What type of branch circuits would not be appliance or lighting?
 
Re: Circuits for panelboard

408.4 Classification of Panelboards. Panelboards shall be classified for the purposes of this article as either lighting and appliance branch-circuit panelboards or power panelboards, based on their content. A lighting and appliance branch circuit is a branch circuit that has a connection to the neutral of the panelboard and that has overcurrent protection of 30 amperes or less in one or more conductors.
(A) Lighting and Appliance Branch-Circuit Panelboard.
A lighting and appliance branch-circuit panelboard is one having more than 10 percent of its overcurrent devices protecting lighting and appliance branch circuits.
(B) Power Panelboard. A power panelboard is one having 10 percent or fewer of its overcurrent devices protecting lighting and appliance branch circuits.
408.15 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 cabinet or cutout box.
A lighting and appliance branch-circuit panelboard shall be provided with physical means to prevent the installation of more overcurrent devices than that number for which the
panelboard was designed, rated, and approved.
For the purposes of this article, a 2-pole circuit breaker shall be considered two overcurrent devices; a 3-pole circuit
breaker shall be considered three overcurrent devices.
 
Re: Circuits for panelboard

408.34 "A lighting or appliance branch circuit is a branch circuit that has a connection to the neutral of the panelboard and that has overcurrent protection of 30 amperes or less in one or more conductors."

408.34(A) "Lighting and Appliance Branch-Circuit Panelboard, A lighting and appliance branch-circuit panelboard is one having more than 10 percent of its overcurrent devices protecting lighting and appliance circuits."

408.34(B) Power panelboard is a panelboard with 10 percent or less of its overcurrent devices protecting lighting and appliance branch circuits.


So basically if a panelboard were feeding mostly (more than 10 percent) 120 volt lighting and receptacle loads then it would be a Lighting and Appliance Branch-circuit Panelboard. If it served only single or 3 phase 208 volt loads with no neutral connection than it would be a Power Panelboard.
 
Re: Circuits for panelboard

I am curious as to why it is ok to be unlimited if its a power panel.How is it safe for it to be unlimited but not if its for lighting ? :confused:
 
Re: Circuits for panelboard

but what difference does it make whether its lighting circuits or something else? I don't get how this makes thigns any safer.

Unless they are thingking that lighting and appliance circuits are more likely to be closer to full load.

The thing is one would be inclined to think that the main would trip and protect the panelboard from overheating long before a fire started.
 
Re: Circuits for panelboard

For many years NYC didn`t follow the NEC they had thier own code that IMO kept the union guys working and drove the cost throught the roof.We buy Homeline 200 amp mbr panels that dont accept tandems,but the sub panels are dual rated 4/8 6/12 12/24.As stated look at the buss bars they let you know where tandens can be used.In a pinch wire nut circuits together to make it legal :D
 
Re: Circuits for panelboard

Had an inspection many years ago that was red tagged. 200Amp panel with 30 out of 40 spaces used. Inspector ADDED up all the amps on the breakers and said it was overloaded!!
House was for an EE. He called the inspection office and the conversation started something like this: "My attorney will be calling to have the incompetent inspector removed from his job. I want an inspection now!"
The chief inspector came out and found absolutely nothing wrong.
Never saw the first guy after that!!
 
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