20A breakers

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pa electrician

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How many 20Amp breakers can you put in a 40 space panel? (per the NEC)

When a panel is 200 amps, and the whole panel is filled with 20A breakers, isn't that a bit much? Even at 80% of the breakers load rating---- 16A times 40 is = to ALOT of amps through the main breaker.

And what's the wrost that can happen?
Maybe, lights that dim once in a while.
 
Re: 20A breakers

You do not add the face value of the breakers up to figure this out, if you did, a 40 ckt panel would equate to 800 amps - with a 200 amp main, that would not work.

Most ckts do not draw what the value of a breaker, you may only have a few amps (load) on a 20 amp breaker. Not only that, but the loads may not all be active at the same time - that is diversity.

When calculating the load - hopefully before the size of the overcurrent device supplying the panel, that is what should determine the size.
Remember that a 200 amp single phase service has 200 amps available on each leg (phase), that is a lot of power (48000VA).

[ November 03, 2005, 06:55 AM: Message edited by: pierre ]
 
Re: 20A breakers

the answer is clearly 40.

whether your panel can supply enough current to feed all those loads is something else.
 
Re: 20A breakers

40
Wrong, it's 41 because of the main breaker. tehehe
And if you use piggyback breakers you can fit twice as many breakers.
Sorry, no cookies for you

[ November 04, 2005, 06:54 AM: Message edited by: pa electrician ]
 
Re: 20A breakers

Originally posted by pa electrician:
Wrong, it's 41 because of the main breaker. tehehe
And if you use piggyback breakers you can fit twice as many breakers.
Sorry, no cookies for you [/QB]
Click to expand...
Well if you say so. :confused:
 
Re: 20A breakers

Originally posted by pa electrician:
40
And if you use piggyback breakers you can fit twice as many breakers.
Click to expand...
Well that would be a code violation, go to that online NEC and read article 408.

Roger

[ November 04, 2005, 07:13 AM: Message edited by: roger ]
 
Re: 20A breakers

Originally posted by pa electrician:
Well if you say so. :cool:
Click to expand...
And you're wrong again.

408.xx 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.
Click to expand...
I left the specific section number off so you have an excuse to use your online NEC. :cool:

[ November 04, 2005, 08:09 AM: Message edited by: georgestolz ]
Click to expand...
 
Re: 20A breakers

Originally posted by pa electrician:
And if you use piggyback breakers you can fit twice as many breakers.
Sorry, no cookies for you
Click to expand...
Well if your cookbook reading is as good as your code book reading I certainly don't want your cookies. :D
 
Re: 20A breakers

Originally posted by electricmanscott:
Well if your cookbook reading is as good as your code book reading I certainly don't want your cookies. :D
Click to expand...
Really! :eek:
 
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