Service size

Inspected a 200 amp panel that has 3/0 copper SEC. This is in a suburb of Chicago. Shouldn’t the cable be 2/0 copper? It passed the cities electrical inspection at the time of construction in 2003 according to the tag on the panel.

You are aware that 3/0 is larger than 2/0, correct? If 2/0 is needed, why would installing a larger size be an issue?

It was a “if a little is good then more is better” man. :smiley:

I am looking at 2 charts, one says 2/0 for 200 amp and the other says 3/0 for 200 amp for use in the USA. I know 3/0 is larger and should be OK, I just like to be sure when it comes to electrical for the obvious safety concerns.

Bigger is better as stated above.

That’s what she said Bob. lol

Thanks guys

There are many local town governments that require 3/0 rather than using 2/0. If you have time, go to that town’s code addendums online.


#3/0 Copper SE cable used as service entrance conductors has an ampacity of 200 amps. {NEC Table 310.16}

Reduced sized service entrance conductors are permitted by NEC Table 310.15(B)(6) which allows the use of #2/0 Copper SE cable in 3 wire, 120/240 volt, single phase, dwelling services. Around here the standard for a 200 amp dwelling service would be #4/0 aluminum SE cable.