If the service entrance conductor is rated for 200 amps but the main disconnect breaker is only rated for 100 amps?

is this considered a defect, the electrical section just says-

“Again, the rating (or fuse or breaker size) of the disconnect relates to the total amperage available within the home. If the main disconnect is, for example, rated only at 100 amps, it doesn’t matter that the SECs are rated for 200 amps.”

It would be a defect if the main breaker was 200 amp but the SE was 100. The breaker needs to be sized to protect the wire.

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Morning, Andrew. Hope you are doing well.

Andrew, it doesn’t matter that SEC, Service Entrance Cables are rated for 200 amps or 400 amps and the main disconnect is rated at 100 Max ampacity. As long as the main disconnect rating is equal to or lower than the power/ampacity feeding it.

Remember, enclosures are part of the mix and can be rated to maximum ampacity as well. The main disconnect must be equal to, or less than, the maximum enclosure rating. An enclosure rated for 200 Amp of power it is safe to install a 200 Amp or less main disconnect.

Here is Basic Electrical Inspection Guide from InterNACHI House of Horrors Florida.
Hope that helps.


Simon has it… … :+1:

Let me try to explain this another way. You do not disconnecting from the SEC. Service Drops or Underground Laterals Provide All Power. There is alway power unless the electrical grid goes down. Then it is down for that entire grid.
The SEC Service Entrance Cables Drop or Underground Lateral are supplies and repaired by PoCo, Power company, and fed/feed to the service enclosure or to a main disconnect.
Where the home’s power is rated, both the main enclosure and main disconnecting means. For a home, you disconnect in service panel.
Most homes require an electrical service of at least 100 amps. That would be a reference point for required ampacity.

To size an electrical service, look at the main components of the homes electrical distribution system. SEC, the conduit, the meter, the panel and the main breaker. Whichever has the lowest amperage rating is your overall home’s electric service rating.

I hope that made sense.

At a quick glance there are several inaccuracies in those photo’s.

Morning, Robert.
Hope to find you well.

I was hoping you would chime into the thread. Would you care to elaborate.

Sure, there quite a bit to digest so give me a little time and I’ll post some comments.

thanks for the help everyone