1/0 copper SEC

Please clarify for me if 1/0 copper is suitable for a 200 amp breaker.
My understanding is 150, max 175 for SEC.

Thanks, seems undersized, looks to me like a 150 amp breaker should be installed.

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You’re correct. The max for 1/0 is 150 amp.

200 amp requires 3/0 (copper).

Thanks, I wanted to make sure and I appreciate the feedback.

Technically the NEC states 2/0 copper is required. However, your local may require 3/0 copper.

Jeff

David according to NEC 2008. No! also according InterNachi training. No!
Looks like we all got to you at the same time.:wink:

That’s correct. With NEC 2/0 co is minimum. Some of my locals have been requiring 3/0. Either way what David has is undersized. :slight_smile:

1/0 copper is not suitable for a 200 amp main. NEC table 310.15 B 7 lets you use it for 175 amps not 200. A 200 amp service would need 2/0 copper or 4/0 aluminum.

Hope this helps:

Table 310.15(B)(7) Conductor Types and Sizes for
120/240-Volt, 3-Wire, Single-Phase Dwelling Services and
Feeders. Conductor Types RHH, RHW, RHW-2, THHN,
THHW, THW, THW-2, THWN, THWN-2, XHHW,
XHHW-2, SE, USE, USE-2
Conductor (AWG or kcmil)
Service or Feeder
Rating (Amperes) Copper
Aluminum or
Copper-Clad
Aluminum

(Amps are first, the copper wire size then aluminum)

100 4 2
110 3 1
125 2 1/0
150 1 2/0
175 1/0 3/0
200 2/0 4/0
225 3/0 250
250 4/0 300
300 250 350
350 350 500
400 400 600

According to NEC Table 310.15(B)(7) #1/0 copper is good for 175 amps. Your close up photo is of the neutral are the ungrounded conductors also #1/0? The neutral is permitted to be smaller.