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Old 08-22-2011, 12:54 PM   #1
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Max size wire for for service drop conduit?


I have searched this forum and done my best interpreting the most recent California Electrical Code but I still have questions. I want to upgrade my main service from 100 to 200amps - pretty basic. I do not want to replace the conduit that runs in the wall from the meter to the roof masthead for the service connection. It is 1 1/4" diameter EMT. My research leads me to conclude that I need 2/0 copper and it may or may not fit in the conduit according to fill charts depending on the type of insulation. What types of insulation may I use in CA in EMT for Service drop? Is it OK to provide copper even though the power company's service lateral is Aluminum?

As a side question, why in the world are you allowed to fill the conduit more if you are using more than 2 wires?!

Thank you all!

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Old 08-22-2011, 01:29 PM   #2
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Max size wire for for service drop conduit?


2/0 copper is correct, but you are not gonna get it into a 1 1/4" conduit.

Fill ratio is also based on what is called "jam effect".

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Old 08-22-2011, 04:00 PM   #3
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Max size wire for for service drop conduit?


need 1 1/2 for 3 #2/0.nec chapter 9 table 4,table 5.do thse calcs from there.the sq in of 2/0 thwn is .2223.you need 3 wires multiply by 3 gets .6669.1 1/2 emt is .814 for over two wires.so 1 1/2 is what you need.learn to0 use tables in the book.article 310 is for ampacity of conductors.

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Old 08-22-2011, 04:48 PM   #4
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Max size wire for for service drop conduit?


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Originally Posted by oleguy74 View Post
need 1 1/2 for 3 #2/0.nec chapter 9 table 4,table 5.do thse calcs from there.the sq in of 2/0 thwn is .2223.you need 3 wires multiply by 3 gets .6669.1 1/2 emt is .814 for over two wires.so 1 1/2 is what you need.learn to0 use tables in the book.article 310 is for ampacity of conductors.
Or you can do it the easy way and use Annex C.
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Old 08-22-2011, 05:05 PM   #5
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Max size wire for for service drop conduit?


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Or you can do it the easy way and use Annex C.
until you have wires of different size.then you need to calculate.example,3 #2/0 and one #4.would still be 1 1/2 but you don't know till you calc.just sayin...
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Old 08-22-2011, 05:31 PM   #6
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Max size wire for for service drop conduit?


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until you have wires of different size.then you need to calculate.example,3 #2/0 and one #4.would still be 1 1/2 but you don't know till you calc.just sayin...
I was just teasing.
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Old 08-22-2011, 05:33 PM   #7
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Max size wire for for service drop conduit?


right on.just onfo to help the OP.since he is looking in the book.....might as well look at it all...
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Old 08-23-2011, 10:55 PM   #8
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Max size wire for for service drop conduit?


Well thanks very much, I appreciate instruction on how to properly use the tables. I see I was looking at the wrong column in the fill charts - duhh!

I also see that one of my original questions still applies: what insulation types must I use in this application since I would like to maximize my service without replacing conduit? (My other option would be to run new conduit outside the wall - but it doesn't look so nice).
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Old 08-23-2011, 11:34 PM   #9
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Max size wire for for service drop conduit?


THWN, RHW, and XHHW are common.

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