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diabolical · Feb 14, 2010, 08:00 AM

When I checked the wire size and ampacity chart I saw that 2/o wire is not suitable for 200A why do electricians use it for 200A services? I also saw that that 3/o is rated for 225A so why not use that and install 225A panels?

tkrussell · Feb 14, 2010, 08:11 AM

Please don't piggyback a new question on an old thread.

The National Electric Code recognizes that residential services will not draw full current, so as per Table 310.15 (B) 6, permits a 200 Amp residential service to use #2/0 copper.

stanfortyman · Feb 14, 2010, 08:15 AM

Originally Posted by diabolical

when i checked the wire size and ampacity chart i saw that 2/o wire is not suitable for 200A why do electricians use it for 200A services?

NEC 310.15(B)(6) is what is used to size service conductors for dwellings, NOT T310.16

Originally Posted by diabolical

i also saw that that 3/o is rated for 225A so why not use that and install 225A panels?

Because 225A is an odd size for typical main breaker single phase panels, especially in a residential application.

diabolical · Feb 14, 2010, 08:32 AM

Originally Posted by tkrussell

Please don't piggyback a new question on an old thread.

The National Electric Code recognizes that residential services will not draw full current, so as per Table 310.15 (B) 6, permits a 200 Amp residential service to use #2/0 copper.

What about when bringing feeders off an I-line service for 200A sub-panels for the residence would this consideration recognize sub-panels

tkrussell · Feb 15, 2010, 04:39 AM

If I can imagine what your talking about, an I-Line distribution panelboard for a multi-family dwelling, and the 200 amp feeders to each apartment/condo.

Each feeder is to one residential dwelling, and Table 315.15(B)6 applies.

If I am not correct in my assumption, more explanation would be great regarding your situation.

lilrob482club · Apr 3, 2012, 11:14 AM

Because you have two current carrying conductors. You have two number 2 copper cables. You can't put 200A on one cable, but your home if you look at it should have a cable marked red and a plain black one. The way you're picturing it would be 200A divided by one wire equaling 200A per conductor which I agree is an overload, but it's really 200A divided by 2 wires meaning only 100A ampacity per conductor and even that is not the continuous load because it's considering your garbage disposal which is only on for short bursts, your washer, dryer, refrigerator compressor, etc. all large amp currents that are only on for a percentage of time. Jesus Christ bless you.

stanfortyman · Apr 3, 2012, 12:07 PM

Originally Posted by lilrob482club

Because you have two current carrying conductors. You have two number 2 copper cables. You can't put 200A on one cable, but your home if you look at it should have a cable marked red and a plain black one. The way you're picturing it would be 200A divided by one wire equaling 200A per conductor which I agree is an overload, but it's really 200A divided by 2 wires meaning only 100A ampacity per conductor and even that is not the continuous load because it's considering your garbage disposal which is only on for short bursts, your washer, dryer, refridgerator compressor, etc. all large amp currents that are only on for a percentage of time. Jesus Christ bless you.

WHAT are you talking about?? Divided by one wire and divided by two wires?
Sorry, that is not how it works.

Besides, his thread is over two years old.

tkrussell · Apr 3, 2012, 12:47 PM

Lilrob, please refrain from giving anyone electrical advice, as you clearly do not have a working understanding of how an electrical service operates.

If you give out advice to those you know and love in your everyday life,you are doing a huge disservice to those people.

Jesus Christ will not be pleased with you.

stanfortyman · Apr 3, 2012, 02:35 PM

Originally Posted by tkrussell

Lilrob, please refrain from giving anyone electrical advice, as you clearly do not have a working understanding of how an electrical service operates.

If you give out advice to those you know and love in your everyday life,you are doing a huge disservice to those people.

Jesus Christ will not be pleased with you.

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