Service entrance conductor rating

SEC is aluminum 2/0 which is rated for 150amp. Main disconnect is 200. On the main disconnect it says alum 2/0-300. That’s 150-250 amp. Originally I thought the disconnect was too large for the sec. Now I’m not so sure. Is it not as simple as following the conductor rating chart I attached?

Remember, to rate the amperage, one typically, uses the lesser of these 3 things:

  1. The SEC size
  2. The service disconnect size
  3. The cabinet rating

So, with the info I see, your service size would be 150 amp.

I believe that relates to the size conductor that the Service disconnect lugs can accept.

Yes I do see it says lugs. And it is rated for 2/0 because copper 2/0 is 200 amp. Gotcha. Thank you

You are correct the 200 amp OCPD is too large for the 150 amp aluminum conductors. This was the service disconnect, meaning there was no other OCPD between it and the meter?

Correct. The home has (2) metered 200 Amp panels. No remote disconnect. The meters are right behind the panels on the exterior. I included a pic. The disconnect you see it’s for the AC compressor. There other was for the old great pump no longer in service.

Don’t overload it :slight_smile: